Process, Insight, and Empirical Method
Argument for the Compatibility of the Philosophies of Alfred North
Whitehead and Bernard J. F. Lonergan and Its Implications for
Dissertation Submitted to the Faculty of the Divinity School, The
University of Chicago, for the Degree of Doctor of Philosophy
Thomas Hosinski, C.S.C.
The Tenability of Whitehead’s and Lonergan’s Interpretations of
This chapter is an interlude—though
a necessary one—in the development of the main thesis and argumentation
of my dissertation. It is necessary in order to establish critically
the status of Whitehead’s and Lonergan’s interpretations of empirical
scientific method. We have already seen in Chapter I the extent to
which both of their philosophies depend on an accurate and tenable
interpretation of empirical scientific method.
Fundamentally, then, if Whitehead’s
and Lonergan’s interpretations of empirical method could not be judged
tenable, this would seriously weaken their own philosophies and the
foundations I believe their philosophies offer for theology, as well as
the argument I wish to formulate concerning the compatibility of their
philosophies. Hence apart from any cogency and self-evidence their
discussions, analyses, and arguments may have—and I, obviously, am of
the opinion that such cogency and self-evidence is considerable—I must
discover independent lines of evidence for judging that their
interpretations of empirical scientific method are tenable.
Under normal circumstances such
lines of evidence might be elicited by considering critical studies of
their work done by philosophers of science. This procedure, however,
cannot be followed in this case for the simple reason that critical
studies of Whitehead’s and Lonergan’s interpretations of empirical
scientific method are almost non-existent.
There is one critical
study of Lonergan’s interpretation of empirical scientific method done
by a noted philosopher of science: Mary Hesse, “Lonergan and Method in
the Natural Sciences,” in Patrick Corcoran, ed., Looking at
Lonergan’s Method (Dublin: The Talbot Press, 1975), pp. 59-72.
Unfortunately, this analysis is so riddled with basic misunderstandings
of Lonergan’s thought that it is of negligible critical value. There
are also the following studies in Spirit as Inquiry: Studies in Honor
of Bernard Lonergan, originally published in Continuum 2
(1964): 300-553: Patrick A. Heelan, “A Realist Theory of Physical
Science,” pp. 334-342; and Edward M. MacKinnon, “Cognitional Analysis
and the Philosophy of Science,” pp. 343-368. Heelan’s study is not
critical, but an appreciative attempt to argue against linguistic
analysts’ interpretations of science. MacKinnon’s study is mainly an
attempt to “build bridges” between Lonergan’s analysis and the
contemporary philosophy of science traditions.
In fact, with regard to the interpretation of scientific method, the
work of both Whitehead and Lonergan has been virtually without influence
in the community of philosophers of science. One can understand why
Lonergan, a professional theologian, might be unknown among philosophers
of science, but it is surprising to discover that Whitehead also is by
and large ignored by them. With just a few exceptions, his work beyond
1922 is simply not referred to by philosophers of science.
For critical studies
of Whitehead’s philosophy of science (i.e., the concepts of his
philosophy of science) see Appendix IV and Bibliography of Palter,
Whitehead’s Philosophy of Science, pp. 236-243. While there are
numerous studies of this sort, I can discover none which addresses
Whitehead’s interpretation of the general method of empirical science.
This is probably the case because Whitehead nowhere engages in an
extended analysis of empirical scientific method and also because his
work after 1922 is “metaphysical”
Thesis, p. 9.]
and was thus considered irrelevant to the modes of interpretation then
dominant in the philosophy of science. In any event, there is a dearth
of critical studies of Whitehead’s and Lonergan’s interpreta-tions of
empirical scientific method, and so I must choose another form of
analysis in order to develop independent lines of evidence.
The best procedure remaining to me
seems to be that of comparison. The task would be simple if there
existed some widely accepted and agreed-upon statement and analysis of
the structure of scientific method to which I could compare the
interpretations of Whitehead and Lonergan. Unfortunately, as anyone
familiar with the state of contemporary philosophy of science knows,
there is no such agreement.
[See Frederick Suppe, ed., The Structure of Scientific Theories.]
Rather, there is a pluralism of
positions within the community of philosophers of science yielding a
wide spectrum of interpretations of scientific method. Obviously, any
attempt to compare Whitehead’s and Lonergan’s interpretations to the
entire spectrum of contemporary interpretations in the philosophy of
science would expand my necessary interlude into several dissertations
in their own right. The course I shall follow, then, is to pick two
representative interpretations from the many available in contemporary
philosophy of science and critically compare Whitehead’s and Lonergan’s
interpretations to them. This ought to be sufficient to enable me to
illustrate that Whitehead’s and Lonergan’s interpretations of scientific
method fall within the spectrum of interpretation offered by
contemporary philosophy of science, and for my purposes this would be
sufficient independent evidence to base the judgment that their
interpretations are tenable.
Finally, though the two thinkers I
have chosen for the purpose of comparison certainly need no
introduction, perhaps something ought to be said about my reasons for
choosing these two in particular. First, both Karl Popper and Michael
Polanyi have produced important interpretations of empirical scientific
method and philosophies of knowing. Their interpretations have been
widely influential for a number of years. On this topic, their names
and work spring immediately to mind. More important than this, however,
is the apparent distance between their interpretations; that is, in
several important respects the difference between their interpretations
gives one a sense of the spectrum of interpretation that exists. For
example, it seems a long way from Polanyi’s “personal knowledge” to
Popper’s “epistemology without a knowing subject.” Thus Popper and
Polanyi serve as good figures for a discussion that aims at being
exemplary rather than exhaustive in its treatment. Thirdly, both Popper
and Polanyi not only have thorough interpretations of empirical
scientific method, but also full-fledged epistemologies situated within
a larger philosophical outlook. Their work is on roughly the same scale
as that of Whitehead and Lonergan, and this will facilitate comparison
of interpretations. Finally, in the philosophy of Karl Popper we find a
well-articulated interpretation of empirical scientific method that at
least initially appears to be in serious disagreement with the
interpretations of both Whitehead and Lonergan, while in the philosophy
of Michael Polanyi we find one that has a marked resonance with them.
This, too, will facilitate a critical comparison of views.
The first section of this chapter
will attempt to summarize Karl Popper’s interpretation of empirical
scientific method and the philosophy of knowing; the second section will
attempt to do the same for Michael Polyani’s interpretation; and the
third section will be the critical comparison of Whitehead’s and
Lonergan’s interpretations to these two.
Karl Popper on
Scientific Method and Knowledge
Karl Popper’s interpretation of
empirical scientific method and the nature of human knowledge has been
developed over several decades and has drawn wide comment and criticism.
Popper’s major works
are: The Logic of Scientific Discovery (New York: Basic Books,
1959; 2nd ed., 1968 hereafter cited as L.Sc.D.], a translation by
the author of Logik der Forschung (Vienna: 1934); two collections
of articles and papers, Conjectures and Refutations: the Growth of
Scientific Knowledge (New York: Basic Books, 1962 hereafter cited as
C.R.], and Objective Knowledge: An Evolutionary Approach
(Oxford: At the Clarendon Press, 1972 hereafter cited as Ob. Kn.;
and Popper’s “Intellectual Biography” and “Replies to My Critics” in
Paul A. Schilpp, ed., The Philosophy of Karl Popper, 2 vols.
[Vol. XIV of The Library of Living Philosophers] LaSalle, Ill.:
Open Court, 1974), 1: 3-181 and 2: 961-1197 respectively. There are two
major collections of commentaries and critical studies: Mario Bunge,
ed., The Critical Approach to Science and Philosophy (New York:
The Free Press, 1 64 ; and the essays in Schilpp, ed., The Philosophy
of Karl Popper.
As Popper himself has repeatedly stated, the ideas with which he
interprets empirical scientific method and develops his philosophy of
knowledge are quite simple. In this section I will attempt to
communicate the simplicity of his basic interpretation without becoming
involved in the detailed, minute criticism his interpretation has
It is perhaps best to begin with a
brief consid-eration of the philosophical context from which Popper
approaches the problem of knowledge and empirical method. In the
preface to the English edition of his major work, The Logic of
Scientific Discovery, Popper states his conviction that the central
problem for thought
is the problem of cosmology: the
problem of understanding the world—including ourselves, and our
knowledge, as part of the world. All science is cosmology, I believe,
and for me the interest of philosophy, no less than of science, lies
solely in the contributions which it has made to it.
15. Popper’s italics omitted.]
In its attempt to contribute to this understanding, in its search for
truth, philosophy does not follow some method peculiar to itself.
There is no method peculiar to philosophy . . .
And yet, I am quite ready to admit
that there is a method which might be described as “the one method of
philosophy.” But it is not characteristic of philosophy alone; it is,
rather, the one method of all rational discussion, and therefore
of the natural sciences as well as of philosophy. The method I have in
mind is that of stating one’s problem clearly and of examining its
various proposed solutions critically.
[Ibid., pp. 15,
16. Popper’s italics. All italics in subsequent quotations from
Popper’s are his.]
Popper’s own concern is to contribute to an understanding of human
knowledge, and he is convinced that the only way of arriving at an
understanding of knowledge is to offer a solution to “the central
problem of epistemology,” namely, “the growth of knowledge.”
Furthermore, “the growth of knowledge can be studied best by studying
the growth of scientific knowledge.”
[Ibid., p. 15.
Popper’s italics omitted.]
This is because scientific
knowledge, in the problem situations it addresses and in the disciplined
way it discusses reasons for accepting or rejecting a theory, offers an
easier entry into the problems and issues involved in knowledge in
general than does common-sense knowledge.
“The problem of
epistemology may be approached from two sides: (1) as the problem of
ordinary or common-sense knowledge, or (2) as the problem of
scientific knowledge. Those philosophers who favour the first
approach think, rightly, that scientific knowledge can only be an
extension of common-sense knowledge, and they also think, wrongly, that
common-sense knowledge is the easier of the two to analyse.” Ibid.,
p. 18; see also pp. 18-22. In formulating his discussion in this
way, Popper is attempting to show why neither “logical analysis” nor
“language analysis” can serve as the main method of epistemology.
Such, in brief, is the general context of Popper’s philosophy.
There are two possible ways of
trying to summarize the main lines of Popper’s interpretation of science
and knowledge. One would be to construct a theoretical approach from
the context I sum-marized above. In this case we would begin by saying
that since we are to study the growth of scientific knowledge from other
sorts of knowledge, and then develop an analysis of how scientific
knowledge changes or grows. This is in fact how Popper proceeds in his
discussion in The Logic of Scientific Discovery. It is also
possible, now that Popper has written his intellectual “Autobiography,”
to summarize his central ideas by showing how he actually brought them
together in his intellectual development. It is the latter course that
I shall choose, partly because I shall be dealing with Popper’s
theoretical discussions below and partly because of the human interest
in tracing the development of personal ideas into a public theory of
Popper, “Intellectual Autobiography,” in Schilpp, ed., The Philosophy
of Karl Popper, 1: 3-181. (Hereafter cited as “Autobio.”)’
Popper attributes the birth of one
of his central ideas to several crucial experiences that all took place
in 1919, his seventeenth year.
[For what follows, see ibid., pp. 23-29.]
In the spring of that year he became convinced by communist propaganda
and for a period of two or three months considered himself a communist.
But in the summer of that year several socialists and communists were
killed in Vienna in an attempt to aid the escape of some communists
under arrest by the police. Popper felt that as a Marxist he bore part
of the responsibility for this tragic incident. The revulsion he felt
caused him to question Marxist theory (which was being presented as
“scientific socialism”) and his own uncritical commitment to the creed
of communism. He decided that he had accepted the complex theories of
Marxism and communism without subjecting those theories to critical
examination so as to arrive at a personal understanding of them, and
that he had also “repressed” his awareness of quite a bit that was wrong
with both the theory and practice of communism. He came to regard the
Marxist and communist creed as dogmatic, and was horrified at how he had
allowed this dogma to suppress his critical thought. It was at this
time, also, that he was investigating Freud’s and Adler’s theories of
psychology, and came to similar conclusions about their dogmatism.
See C.R., pp. 33-39 for another autobiographical account
that treats Popper’s reaction to Freud and Adler.
In the same year, however, Popper learned of Einstein and his theory of
relativity. He was most impressed with Einstein’s clear statement that
if his theory should fail in certain specified empirical tests, he would
regard it as untenable.
Here was an attitude utterly
different from the dogmatic attitude of Marx, Freud, Adler, and even
more so that of their followers. Einstein was looking for crucial
experiments whose agreement with his predictions would by no means
establish his theory; while a disagreement, as he was the first to
stress, would show his theory to be untenable.
This, I felt, was the true
scientific attitude. It was utterly different from the dogmatic attitude
which constantly claimed to find “verifications” for its favorite
theories. Thus I arrived, by the end of 1919, at the conclusion that
the scientific attitude was the critical attitude, which did not look
for verifications but for crucial tests; tests which could refute
the theory tested, though they could never establish it.
[“Autobio.”, p. 29.]
In the next few years Popper
developed his ideas about what separates or “demarcates” scientific
theories from pseudoscientific theories.
[See ibid., pp.
What makes a theory scientific, he
thought, is that it rules out or excludes the occurrence of some
possible events; it predicts that some things will not happen. Popper
then concluded, “the more a theory forbids, the more it tells us.” [Ibid., p. 31.
This is in contrast to pseudoscientific theories that seemed able to
interpret any possible event as a “verification” of the theory. Rather
than simply dismissing dogmatic thought as “unscientific,” however,
Popper concluded that it is “prescientific” and that it represents a
necessary stage in the development of scientific thought. Without
dogmatic thought, critical thought would have nothing to criticize.
At roughly the same time (1922-1926)
Popper was working on the psychology of learning, and his investigations
led him to theorize that most, perhaps all, learning processes consist
in the formulation of expectations (or theories) and the consequent
modification of these expectations by the method of trial and error.
[See ibid., pp. 34-41.]
His investigations of
learning in young children led him to reject the psychological theory of
learning by induction (or repetition). His research seemed to show that
children have certain “inborn” needs for and expectations of structural
invariants in their environment, and their learning (especially true of
language acquisition) seemed to consist in repeated trials (attempting
to meet their inborn expectations) and correction by the (critical)
elimination of errors. This led Popper to theorize that learning, or the
logic of discovery, does not take place by observing and then
generalizing (inductive inference), but rather that observation is
always guided by an aim, by problems needing resolution, by conjectures,
All this led me to the view that
conjecture or hypothesis must come before observation or perception: we
have inborn expectations; we have latent inborn knowledge, in the form
of latent expectations, to be activated by stimuli to which we react as
a rule while engaged in active exploration. All learning is a
modification (it maybe a refutation) of some prior knowledge and thus,
in the last analysis, of some inborn knowledge.
Thus by 1926 Popper had developed
several of the key ideas which he would use to interpret empirical
scientific method and human knowledge, but at first he did not connect
them. It was not until after his Ph.D. examination in 1928 that he
finally made the crucial connection in his ideas which has guided and
dominated his interpretation ever since. Since Popper describes this
and summarizes all the points I shall discuss below, I will quote a
lengthy passage from his “Autobiography.”
It was only after my Ph.D.
examination that I put two and two together, and my earlier ideas fell
into place. I understood why the mistaken theory of science which had
ruled since Bacon—that the natural sciences were the inductive
sciences, and that induction was a process of establishing or justifying
theories by repeated observations or experiments—was so deeply
entrenched. The reason was that scientists had to demarcate
their activities from pseudoscience as well as from theology and
metaphysics, and they had taken over from Bacon the inductive method as
their criterion of demarcation. . . . But I had held in my hands for
many years a better criterion of demarcation: testability or
Thus I could discard induction
without getting into trouble over demarcation. And I could apply my
results concerning the method of trial and error in such a way as to
replace the whole inductive methodology by a deductive one. The
falsification or refutation of theories through the falsification or
refutation of their deductive consequences was, clearly, a deductive
inference (modus tollens). This view implied that scientific
theories are either falsified or for ever remain hypotheses or
Thus the whole problem of scientific
method cleared itself up, and with it the problem of scientific
progress. Progress consisted in moving towards theories which tell us
more and more—theories of ever greater content. But the more a theory
says the more it excludes or forbids, and the greater are the
opportunities for falsifying it. So a theory with greater content is one
which can be more severely tested. This consideration led to a theory
in which scientific progress turned out not to consist in the
accumulation of observations but in the overthrow of less good theories
and their replacement by better ones, in particular by theories of
greater content. Thus there was competition between theories—a kind of
Darwinian struggle for survival.
Of course theories which we claim to
be no more than conjectures or hypotheses need no justification (and
least of all a justification by a nonexistent “method of induction,” of
which nobody has ever given a sensible description). We can, however,
sometimes give reasons for preferring one of the competing conjectures
to the others, in the light of their critical discussion.
[Ibid., p. 62-63. ]
Thus by 1928 or 1929 the main ideas that Popper would use to develop his
major interpretation of science and human knowledge in Logik der
Forschung had already come together. I will now turn to a more
detailed consideration of this interpretation.
Problem and Criterion of Demarcation
Popper regards his solution to the
problem of demarcation as the center of his philosophy and states that
unless this idea is understood both in its simplicity and its complexity
his philosophy will be misunderstood.
[“Replies to My
Critics,” in Schilpp, ed., The Philosophy of Karl Popper, 2: 976,
979. (Hereafter cited as “Replies.”)]
The problem of demarcation, as we have see briefly above, has to do with
what criterion is to be used in order to distinguish between science on
the one hand and nonscience on the other. It is important to recognize
that this criterion does not distinguish between true and false
scientific theories, but attempts rather to establish what can properly
be called “science” (in the sense of empirical science) and what
[See ibid., p. 976.] This allows Popper to place
together in the category of “nonscience” such diverse forms of thought
as logic, metaphysics, theology, psychoanalysis, astrology, and so
forth, without the necessity of distinguishing between them.
The criterion of demarcation,
obviously, must be derived from an understanding of what it is about
science that makes it unique. That is, this criterion presupposes an
interpretation of science. We can most easily understand Popper’s
proposed criterion by recalling how impressed he was with Einstein’s
statement that if his theory failed to meet certain specified empirical
tests, he would regard it as untenable. The view of science implicit in
Popper’s criterion of demarcation is that science is bold theorizing or
conjecturing, but conjecturing that states its consequences in such a
way that the consequences may be tested and possibly refuted by the
facts of experience. Popper summarizes this view of science and his
criterion of demarcation in this way.
There is a reality behind the world
as it appears to us, possibly a many-layered reality, of which the
appearances are the outermost layers. What the great scientist does is
boldly to guess, daringly to conjecture, what these inner realities are
like. This is akin to mythmaking. . . . The boldness can be gauged by
the distance between the world of appearances and the conjectured
reality, the explanatory hypothesis.
But there is another, a special kind
of boldness—the boldness of predicting aspects of the world of
appearance which so far have been overlooked but which it must possess
if the conjectured reality is (more or less) right, if the explanatory
hypotheses are (approxi-mately) true. It is this more special kind of
boldness which I usually have in mind when I speak of bold scientific
conjectures. It is the boldness of a conjecture which takes a real
risk—the risk of being tested, and refuted; the risk of clashing with
Thus my proposal was, and is, that it is this second boldness, together with the readiness to
look out for tests and refutations, which distinguishes
“empirical” science from nonscience, especially from
prescientific myths and metaphysics.
Ibid., pp. 980-981. In
L.Sc.D., p. 27, Popper summarizes his view of science in this way:
“A scientist, whether theorist or experimenter, puts forward statements,
or systems of statements, and tests them step by step. In the field of
the empirical sciences, more particularly, he constructs hypotheses, or
systems of theories, and tests them against experience by observation
As we shall see when we come to discuss the detailed interpretation of
science and empirical scientific method Popper develops from this
position, there are a number of qualifications which must be introduced
for a full understanding of his criterion of demarcation. First,
however, I must discuss the more famous formulation of Popper’s
criterion and then, in the following subsection, how he judges that it
solves the closely related problem of induction.
Popper’s criterion of demarcation is
more familiarly known as falsifiability, though it can also be called
testability. The simple statement of this criterion is as follows.
. . . I shall certainly admit a
system as empirical or scientific only if it is capable of being
tested by experience. . . . not the verifiability but the
falsifiability of a system is to be taken as a criterion of
demarcation. In other words: . . . it must be possible for an
empirical scientific system to be refuted by experience.
L.Sc.D., pp. 40-41. It
should be noted that it is incorrect to speak of Popper’s criterion as
“falsification”; he does not require that a “scientific” or “empirical”
statement actually be tested, only that it is capable of
being tested. See ibid., pp. 86-87.
Since Popper’s criterion has often
been confused with the logical positivist criterion of meaningfulness
which he in fact criticized from the beginning, it would be good to
consider his criticisms of the logical positivist interpretation before
we discuss several possible objections to his criterion. This contrast
with the logical positivist interpretation will also make the meaning of
Popper’s criterion more clear.
Popper originally developed his
ideas without knowledge of the logical positivist interpretation of
science and its criterion of meaningfulness, but when he became
acquainted with the ideas and the men of the Vienna Circle, he
immediately saw how his ideas related to the problems they were
addressing, and he was convinced that his ideas were better than theirs.
Popper discusses this
in C.R., pp. 39-41; L.Sc.D., p. 40 note *3; “Autobio.,”
pp. 63-71; and at some length in “Replies,” pp. 963-976. A
non-biographical or theoretical criticism of logical positivism is
argued in L.Sc.D., pp. 34-39, 49-53, and passim; and in
C.R., pp. 253-292.
As Popper saw, the logical positivists of the Vienna Circle were trying
to solve the problem of demarcation by providing a criterion for
distinguishing between science and nonscience. Yet their method of
approach, Popper argued, involved them in two major errors. The first
of these errors was their anti-metaphysical programme. In attempting to
lay the coup de grace to metaphysics, the logical positivists
chose meaningfulness as the criterion of demarcation between science and
metaphysics. According to this criterion, the only meaningful
statements are empirical scientific ones and all others (most especially
metaphysical statements) are “meaningless.” They were, in short,
attempting “to prove that metaphysics by its very nature is nothing but
nonsensical twaddle—’sophistry and illusion,’ as Hume says, which we
should ‘commit to the flames.”
[L.Sc.D., p. 35.]
This choice of criterion was bound to lead to trouble, in Popper’s
estimation, since the history of science repeatedly illustrates that
“metaphysical ideas are often the forerunners of scientific ones.
“Autobio.,” p. 63.
Popper has continually argued that metaphysics can make contributions
to science and knowledge. I will return to this point below.
It seemed inconsistent and unreasonable to Popper to label ideas
meaningless at one stage of their development, but meaningful at a later
stage. It addition, it seemed obvious to him that metaphysical ideas
were meaningful, but that whether or not they were scientific was a
The second major error of the
logical positivists was this. The criterion of meaningfulness merely
shifted the problem, and then another criterion to distinguish between
meaningfulness and meaninglessness was necessary. The members of the
Vienna Circle recognized this, and chose verifiability as their
criterion of meaningfulness. Verifiability, as Popper says, “was taken
as being the same as provability by observation statements.
[Ibid.] This, however, was really just
another way of restating the classic idea of induction. Popper’s
logical analysis of science (and his study of Hume) had already
convinced him that there really was no such thing as inductive inference
in empirical science, and that inductive inference was logically
. . . inference to theories, from
singular statements which are “verified by experience” (whatever that
may mean), is logically inadmissable. Theories are, therefore, never
empirically verifiable. If we wish to avoid the positivist’s mistake of
eliminating, by our criterion of demarcation, the theoretical systems of
natural science, then we must choose a criterion which allows us to
admit to the domain of empirical science even statements which cannot be
verified. [L.Sc.D., p.
Popper saw, and argued at length
in numerous papers and articles.]
that his criterion of falsifiability
avoided the pitfalls resulting from the use of meaningfulness and
verifiability as the dual criteria of demarcation.
Because Popper has often been
misunderstood as proposing falsifiability instead of verifiability as
the criterion of meaningfulness, it must be emphasized that he
disagrees entirely with the use of meaningfulness as a criterion.
[Thesis, p. 132
note 2 for references.]
He is careful to comment on numerous occasions that non-scientific
statements are meaningful, and he finds any attempt to distinguish
between science and nonscience on the basis of meaningfulness to be
fruitless and to result in numerous difficulties and absurdities. When
he prepared the English edition of Logik der Forschung Popper
included this note:
Note that I suggest falsifiability
as a criterion of demarcation, but not of meaning. Falsifiability
separates two kinds of perfectly meaningful statements: the falsifiable
and the non-falsifiable. It draws a line inside meaningful language,
not around it.
[L.Sc.D., p. 40
This should make it clear that
Popper is in complete disagreement with the logical positivist
interpretation of science and metaphysics.
Before moving to a consideration of
Popper’s analysis and solution of the problem of induction, I will
briefly discuss three possible objections to his criterion of
Popper raises and
answers these objections in ibid. , pp. 41-42.
Popper’s response to these objections clarifies the nature of his
proposal. The first objection is that if science is supposed to give us
positive information about the world, how can it be characterized by a
negative requirement, such as refutability? Popper responds that this
objection carries little weight, for he is able to argue that “the
amount of positive information about the world which is conveyed by a
scientific statement is the greater the more likely it is to clash,
because of its logical character, with possible singular statements.”
[Ibid., p. 41. The detailed argumentation is on pp. 112-145.]
That is, the more it risks falsifiability, the greater is its actual
A second possible objection is that
the criterion of falsifiability seems liable to the same sorts of
objections raised against verifiability. Popper argues that this is not
the case, however, because his proposal “is based upon an asymmetry
between verifiability and falsifiability; an asymmetry which results
from the logical form of universal statements.”
A universal statement cannot be derived logically from singular
statements, but it can be contradicted by singular statements.
Consequently it is possible by means
of purely deductive inferences (with the help of the modus tollens
of classical logic) to argue from the truth of singular statements to
the falsity of universal statements. Such an argument to the falsity of
universal statements is the only strictly deductive kind of inference
that proceeds, as it were, in the “inductive direction”; that is, from
singular to universal statements.
The third objection is that even if
this asymmetry is admitted, it is impossible ever to falsify completely
any theoretical system. It is always possible to find some way of
avoiding falsification, and this might seem to make the logical value of
Popper’s criterion dubious at best. Popper admits the truth of this
objection, but argues that this does not destroy his proposal, because
of the way he will characterize empirical method.
. . . empirical method shall
be characterized as a method that excludes precisely those ways of
evading falsification which, as my imaginary critic rightly insists, are
logically possible. According to my proposal, what characterizes the
empirical method is its manner of exposing to falsification, in every
conceivable way, the system to be tested. Its aim is not to save the
lives of untenable systems but, on the contrary, to select the one which
is by comparison the fittest, by exposing them all to the fiercest
struggle for survival. [Ibid., p.
Thus the criterion of falsifiability
ultimately is able to demarcate science from nonscience, in Popper’s
view, because it can characterize empirical method as a radical
commitment to testing. Moreover, this makes it possible to distinguish
between what is actually scientific and what is not. It makes it
possible, for example, to distinguish between a scientist’s scientific
opinions and his or her nonscientific ones (including any dogmatic
clinging to a theory that is no longer tenable). The importance of this
characterization of empirical method will become more evident in later
The Two Problems of
Popper is of the opinion that his
criterion of falsifiability and the understanding of human knowledge
connected with it presents a solution to the age-old problem of
induction, and he feels that this is the most widely neglected of his
Knowledge: My Solution of the Problem of Induction,” Chapter 1, Ob.
Kn., pp. 1-31. See also Ob. Kn., pp. 85-105; “Autobio.,” pp.
112-118; and “Replies,” pp. 1013-1027. These are the most extended
analyses of the problem of induction, though Popper frequently discusses
it briefly in all his books.
In his lengthier discussions of induction, Popper prefers to present the
problem against the background of what he calls the “common-sense theory
See “Replies,” pp.
1016-1018; and Ob. Kn., p. 3. I might also note that Popper
draws an interesting distinction between “common-sense realism” and “the
common-sense theory of knowledge.” While he regards the former as true
and as an idea of great importance, he argues that the latter (the
source of the common-sense theory of induction) is thoroughly mistaken.
See especially Ob. Kn., pp. 32-84 and 341-361.
This is the view that all knowledge is the result of past observations,
and that all expectations regarding the future occurrence of repeating
phenomena (e.g., that the sun will rise tomorrow) are also due to past
observations. Popper argues that Hume rightly challenged this common
sense view of induction, and showed by his analysis that
induction by repetition was
logically untenable—that rationally, or logically, no amount of observed
instances can have the slightest bearing upon unobserved instances. This
is Hume’s negative solution of the problem of induction, a solution
which I fully endorse.
But Hume held, at the same time,
that although induction was rationally invalid, it was a psychological
fact, and that we all relied on it.
[“Replies,” p. 1018.]
There are, then, two separate
problems of induction: the logical problem and the psychological
problem. The logical problem can be stated in this way: “Are we
rationally justified in reasoning from repeated instances of which we
have had experience to instances of which we have had no experience? [Ibid.
Hume argued that we are not
rationally justified in so reasoning, no matter how many repetitions
there are. He further argued that the logical conclusion is the same
even if we ask only for probability instead of for certain knowledge.
With this analysis Popper is in complete agreement. The psychological
problem of induction can be stated in this way: “How is it that
nevertheless all reasonable people expect and believe that instances of
which they have “had no experience will conform to those of which they
have had experience?” [Ibid.
Or, to put it differently, why is it that we have such strong
expectations to which we hold with such confidence? Hume’s answer to
this psychological problem was framed in terms of “custom” or “habit”:
because of the power of association we are conditioned by repetition
into a habitual or customary expectation that future occurrences will
conform to those we have experienced in the past. Popper holds that
this analysis is mistaken. In order to explain Popper’s solution of the
psychological problem of induction, however, I must first discuss how he
reformulates and solves the logical problem.
Popper’s main motivation for
reframing the logical problem of induction is to show that irrationalism
is not the necessary outcome of Hume’s logical analysis. Rather, it was
the combination of Hume’s correct logical and incorrect psychological
solutions that led to an unintended irrationalism.
On this interesting
analysis, which for reasons of brevity I cannot pursue here, see ibid.,
pp. 1019-1020; and Ob. Kn., pp. 4-5, 86-88, 93-95, and 99-101.
Popper reformulates the logical problem of induction by slightly
generalizing and extending its wording: “Are we rationally justified in
reasoning from instances or from counterinstances of which we have had
experience to the truth or falsity of the corresponding laws, or to
instances of which we have had no experience?
[“Replies,” p. 1020.
Italics omitted. See also the slightly different formulation, Ob. Kn.,
Hume’s answer still holds: we are
not justified in reasoning from an instance or any number of instances
to the truth of the corresponding law. To this Popper adds an “equally
we are justified in reasoning
from a counterinstance to the falsity of the corresponding universal law
(that is, of any law of which it is a counterinstance). . . . Induction
is logically invalid; but refutation or falsification is a logically
valid way of arguing from a single counterinstance to—or, rather
against—the corresponding law. . . . there are logically valid negative
arguments leading in the inductive direction: a counterinstance may
disprove a law.
[“Replies,” pp. 1020, 1021.]
The importance of this additional
“equally negative” result is that it allows the development of “a
positive theory of how, by purely rational arguments, we can prefer some
competing conjectures to others’.
p. 1021. See also Ob. Kn., pp. 7-8.]
Popper’s theory of preference can be
summarized quite simply. Although Hume’s solution of the problem of
induction implies that all theories or “laws” must always be regarded as
hypothetical or conjectural, this does not mean that we have absolutely
no basis for rational discussion. Rather, the logically valid negative
argument from counter-instances against the corresponding law (Popper’s
contribution) provides the basis for rational preference. Our theories
and “laws” are nothing but conjectures or guesses, but they aim at the
truth and, if they guess boldly, that is, if they contain a high degree
of informational content and take the risk of being refuted, then we can
subject them all to rigorous testing and rationally prefer those
theories “whose falsity has not been established. [Ob. Kn., p.
8. See pp. 13-23 for the detailed argumentation.]
This does not mean that we ever possess the truth; but our theories do
aim at the truth, and if we constantly subject them to the most
stringent tests and prefer those whose falsity has not yet been
established, then we are acting according to rational criteria.
This is the basis of
Popper’s analysis of the “pragmatic problem of induction.” See ibid.,
pp. 21-23 and “Replies,” pp. 1024-1027.
This leaves us with Popper’s
solution of the psychological problem of induction yet to be discussed.
Popper rejects Hume’s solution to this problem because a logical
analysis reveals that Hume’s solution (conditioned expectation resulting
from association of past repetitions) is actually inductive. Popper
argues that “repetition presupposes similarity, and similarity
presupposes a point of view—a theory, or an expectation.”
[Ob. Kn., p. 24.]
Recall here Popper’s early
conclusion that we have “inborn” expectations which we test against our
experience from the moment of our births. What Popper is arguing is that
in order to identify any occurrence as a “repetition,” we have to
identify it as being similar to some other occurrence, and in order to
identify it as similar we must have a (prior) expectation that there
are similar occurrences. Hence the repetition theory that Hume
proposes is untenable because, in fact, expectations come before any
observations, and so there can be no inductive learning or conditioning
such as Hume proposes.
Popper proceeds to solve the
psychological problem of induction by invoking what he calls “the
principle of transference from logic to psychology.”
[“Replies,” p. 1024. See also Ob. Kn., pp. 6, 23-27, 67-68 and
This principle is: “what is true in
logic is true in psychology.”
Ob. Kn., p. 6. In “Replies,”
p. 1024, Popper qualifies this by adding a phrase: “What is true in
logic must, by and large, be true in psychology.” See also the
qualification of this statement in Ob. Kn., p. 24.
Popper is arguing, in short, that Hume’s solution to the psychological
problem is mistaken because it violates this principle in assuming that
induction is a psychological fact even though it cannot be a logical
fact. Likewise, Popper holds, the unintended irrationalism following
from Hume’s solution must be mistaken.
It will be clear that my principle
of transference guarantees the elimination of Hume’s irrationalism: if I
can answer his main problem of induction, including [the psychological
problem], without violating the principle of transference, then there
can be no clash between logic and psychology, and therefore no
conclusion that our understanding is irrational. [Ob. Kn., p.
Following his principle of transference, Popper solves the psychological
problem of induction by transferring his theory of preference from the
logical world of ideas to the psychological world of learning.
As I shall discuss
below, Popper draws a distinction between the world of physical objects,
the world of subjective experience, and the world of objective
knowledge. He labels these “world 1,” “world 2,” and “world 3”
respectively. He does not consider his proposed solution to the
psychological problem of induction to belong to, his objective (“world
3”) theory of knowledge, but holds that this objective theory of
knowledge can shed light on the “world 2” psychological problem. See
Ob. Kn., pp. 25-26.
That theory of preference provided a method of preferring some competing
conjectures to others by subjecting all conjectures to rigorous tests
and preferring those conjectures that remain unfalsified in the face of
all tests. Popper asserts that the same rational method can be used in
the psychological situation. Why is it that we have such strong
“beliefs” or expectations regarding the future occurrence of events?
The answer Popper proposes is that we cannot avoid such expectations:
these beliefs or expectations “are partly inborn, partly modifications
of inborn beliefs resulting from the method of trial and
error-elimination.” [Ob . Kn., P .
27. For the argumentation in support of this conclusion see pp. 23-26.]
But since the method of trial and
error-elimination corresponds exactly with the logical problem, this
means that our holding of such strong expectations regarding the future
is not the irrational result or mere conditioning by repetition.
Rather, so long as we do subject our “inborn” expectations to testing
and modify them when we detect errors, we are operating according to a
“perfectly” rational method.
See ibid., pp.
24, 27. For Popper’s analysis of how Kant contributed to the solution
of this problem and of his own difference from Kant, see ibid.,
pp. 23-24, 91-93.
In this way Popper regards the psychological problem of induction as
Before proceeding to the theory of
the method of science Popper develops from his analysis of the problems
of induction and demarcation, perhaps a few words are in order
concerning what positions Popper is led to by these discussions. One
major position Popper adopts as a result of his analysis is that all
attempts to justify our theories must be given up. By this he
means that there can be no justification for the claim that a theory is
true. Since there is no induction—no logically valid inductive
inference—there can be no verification. Hence all theories must always
be regarded as hypotheses, and all may be refuted.
See, among many
possible references, ibid., p. 29. This conclusion, though
widely accepted today, was not so when Popper it, and he regards it as
one of his major contributions to philosophy.
This does not mean, however, that we must abandon the search for truth.
. . . our critical discussions of
theories are dominated by the idea of finding a true (and powerful)
explanatory theory; and we do justify our preferences by an appeal to
the truth: truth plays the role of a regulative idea. We test for
truth, by eliminating falsehood. That we cannot give a
justification—or sufficient reasons—for our guesses does not mean that
we may not have guessed the truth; some of our hypotheses may well be
[Ibid., pp. 29-30.]
Thus, though we cannot justify theories, we can justify our preferences
among theories, and we do so by means of the heuristic and regulative
idea of truth. The important conclusion from these positions is that
while we may make contact with the truth, we can never be sure that we
know the truth. All our knowledge must always remain hypothetical and
tentative. I will discuss this theory of knowledge in more detail
below, but first I will give more detailed consideration to Popper’s
analysis of empirical scientific method.
of Empirical Science
Popper’s solution of the problem of
induction and his criterion of falsifiability lead to an analysis of
empirical scientific method. While for reasons of brevity I cannot
enter into a detailed discussion of Popper’s analysis, I can in a
reasonably brief compass describe the basic elements of his
Popper offers the following summary
of the theory of empirical scientific method his analysis leads to:
This solution of the problem of
induction gives rise to a new theory of the method of science, to an
analysis of the critical method, the method of trial and error: the
method of proposing bold hypotheses, and exposing them to the severest
criticism, in order to detect where we have erred.
From the point of view of this
methodology, we start our investigation with problems. We always find
ourselves in a certain problem situation; and we choose a problem which
we hope we may be able to solve. The solution, always tentative,
consists in a theory, a hypothesis, a conjecture. The various competing
theories are compared and critically discussed, in order to detect their
shortcomings; and the always changing, always inconclusive results of
the critical discussion constitute what may be called “the science of
Thus there is no induction: we never
argue from facts to theories, by way of refutation or “falsification.”
[“Autiobio.,” p. 68.
See also the summary offered in C.R., p. 313.]
As is already clear from what we have seen of Popper’s analysis, one
major feature of his interpretation is that scientific method is
completely deductive in character; it consists in methods of
(deductively) testing the consequences of theories or hypotheses.
[See L.Sc.D., pp. 32-33.] The first questions likely to be
raised by someone familiar with the more traditional characterizations
of science are, what of the role of observation; and, if there is no
induction, then how do theories and hypotheses come to be formulated?
Observation (and its associated operation of description) are
reinterpreted by Popper as ways of checking or testing hypotheses. This
interpretation of the role of observation is closely related to Popper’s
argument that all observations are preceded and directed or guided by
theory, that all observations are in fact “theory-laden.”
See, among numerous
possible references, L.Sc.D., pp. 94-95, 106, 423-424; C.R.,
pp. 23, 46-48, 55, 127-129; Ob. Kn., pp. 71-72, 145-146, 258-259,
The command to observe, Popper often notes, cannot be obeyed until we
are told what we are to observe, what we are to look for. This is an
example of how observation in fact always presupposes a particular point
Observation is always selective. It
needs a chosen object, a definite task, an interest, a point of view, a
problem. And its description presupposes a descriptive language, with
property words; it presupposes similarity and classification, which in
its turn presupposes interests, points of view, and problems. . . . It
is quite true that any particular hypothesis we choose will have been
preceded by observations—the observations, for example, which it is
designed to explain. But these observations, in their turn, presupposed
the adoption of a frame of reference: a frame of expectations: a frame
of theories. If they were significant, if they created a need for
explanation and thus gave rise to the invention of a hypothesis, it was
because they could not be explained within the old theoretical
framework, the old horizon of expectations. There is no danger here of
an infinite regress. Going back to more and more primitive theories and
myths we shall in the end find unconscious, inborn expectations.
C.R., pp. 46, 47. Note in
this passage Popper’s appeal to the notion of “inborn” expectations,
which he also used to resolve the psychological problem of induction, as
the basis for his interpretation of the role of observation.
Thus observation, which in the inductivist inter-pretation of empirical
scientific method is the starting point, is in Popper’s deductivist
interpretation shifted to the end stage of the application of scientific
method where it plays the crucial role of being the actual means of
testing theories for errors. The starting point for empirical
scientific method in Popper’s interpretation is a problem (or a p~oblem
situation) which has occurred because of the clash of the investigator’s
expectations (hypotheses) with his or her subsequent experience
[See Ob. Kn.,
pp. 257-265, 287-289; C.R., p. 222; “Autobio.,” pp. 105-106.]
With regard to the question of how
theories come to be formulated, Popper dismisses this question as one of
great interest for psychology but not for an objective theory of
. . . the work of the scientist
consists in putting forward and testing theories.
The initial stage, the act of
conceiving or inventing a theory, seems to me neither to call for
logical analysis nor to be susceptible of it. The question how it
happens that a new idea occurs to a man—whether it is a musical theme, a
dramatic conflict, or a scientific theory—may be of great interest to
empirical psychology; but it is irrelevant to the logical analysis of
scientific knowledge. [L.Sc.D., p. 31.]
While Popper is willing to allow for important roles for imagination and
intuition in the formation and even the testing of theories,
See, for example,
C.R., p. 28: “Neither observations nor reason are authorities.
Intellectual intuition and imagination are most important, but they are
not reliable: they may show us things very clearly, and yet they may
mislead us. They are indispensable as the main sources of our theories;
but most of our theories are false anyway. The most important function
of observation and reasoning, and even of intuition and imagination, is
to help us in the critical examination of those bold conjectures which
are the means by which we probe into the unknown.”
he simply does not think that there is any place for an “objective”
analysis of these faculties in a theory of knowledge, and so he does not
discuss how theories come to be formulated. His analysis begins with a
discussion of problems and then moves to a discussion of how the
guesses, conjectures, hypotheses, and theories we propose as solutions
of problems are tested.
With regard to the character of
hypotheses or theories, Popper’s interpretation ought to be clear enough
from what I have already said. Hypotheses and theories are tentative
conjectures, guesses, which scientists construct in the hope of solving
the problems they are investigating. It is clear that in his view
hypotheses, when they are initially proposed and forever after, have the
logical status of conjectures or guesses. This is another major result
of Popper’s solution to the problem of induction and his logical
critique of the criterion of verifiability. Some guesses, however, are
better than others. The bulk of Popper’s analysis is devoted to a close
study of how empirical science determines whether its guesses are good
or not; in other words, the bulk of his analysis concerns the procedures
It is not necessary to enter into a
discussion of Popper’s detailed analysis of the scientific methods of
testing. He develops at some length an analysis of the logical
conditions necessary for the deduction of predictions from theories; he
analyzes the logical status of the “basic statements” or observations
actually used to test a theory’s predictions; he develops a theory for
comparing various scientific hypotheses in terms of their degree of
testability (which is identical with their degree of empirical or
informational content); and he expands his theory of preference,
especially by formulating his theories of corroboration and
With the exception of
the theory of verisimilitude, these are all discussed in L.Sc.D.
as well as later writings. For the notion of verisimilitude see
especially Ob. Kn., pp. 44-60.
While all of these developments are interesting and have provoked
widespread comment in the philosophy of science, I will not enter into a
discussion of them, given my purpose, since they are all subsumed under
Popper’s general interpretation of empirical scientific method; it is
with this general interpretation that I am concerned.
One conclusion of
Popper’s analysis of testing I ought to mention in passing is that what
is tested is a system of statements, and that if falsification does
occur, it is falsification of the whole theoretical system. It may be
extremely difficult and even impossible to determine which particular
statement or subsystem of statements is responsible for the error, that
is, which has actually been exposed to the falsifying experimental
test. To attribute responsibility for error to a particular statement
or subsystem of statements is, Popper insists, conjectural. (See
L.Sc.D., pp. 75-77; “Replies,” p. 982.) This analysis has an
important result for Popper’s epistemology: it means that if a
falsification does occur, the falsification does not give us knowledge
of exactly what the error is, only knowledge that there is an error
somewhere in the system.
We have already seen Popper’s basic interpretation of empirical
scientific method: it is a critical, method, one that subjects all
proposed theories to the most stringent of tests and one that by its
radical commitment to testing systematically prohibits or excludes all
procedures by which a theory might be “immunized” against falsification
or refutation. The principal purpose of the detailed developments I
alluded to in the previous paragraph is to establish the ways in which
empirical method prohibits immunizing tactics and manifests its
commitment to critical testing of hypothetical knowledge. Thus Popper
continually refers to the method of science as critical method, the
method of boldly proposing hypotheses and criticizing them by trial and
error-elimination. However, as we saw briefly above
[See Thesis, p. 126.] and shall discuss at more length
below, Popper argues that this is the method of all rational discussion.
What characterizes empirical scientific method is that is prohibits
“immunization” of hypotheses against falsification by its commitment to
empirical testing. This, in turn, means that empirical
scientific method, in contrast to rational discussion in general,
demands the prediction of empirical states of affairs which are excluded
by the hypotheses. It demands that the implications of the hypotheses
be tested against the facts of experience in a “crucial experiment”
specifically designed to try to falsify the hypotheses. In short,
though all critical discussion might strive to eliminate “immunizing”
tactics, empirical science alone possesses the means of systematically
assuring that these tactics will be avoided, and these means are the
intersubjective testing of hypotheses by experimentation and
Before moving to a discussion of the
character of scientific knowledge and its growth, we might ask whether
Popper’s interpretation of empirical scientific method is meant to be a
description of how scientists actually proceed, or whether it is a
theoretical model of what scientific method ought to be like. This
question has in fact become a matter of some debate in the discussion
between Popper, his students, and Thomas Kuhn.
See Thomas Kuhn,
“Logic of Discovery or Psychology of Research?,” in Schilpp, ed., The
Philosophy of Karl Popper, 2: 798-819, and Popper’s response,
“Replies,” 2: 1144-1148. Kuhn’s article also appears in Imre Lakatos
and Alan Musgrave, eds., Criticism and the Growth of Knowledge
(Cambridge: Cambridge University Press, 1970), pp. 1-23, with another
response from Popper, “Normal Science and Its Dangers,” pp. 51-58, and
Kuhn’s reply, “Reflections on My Critics,” pp. 231-278. (Hereafter cited
as Criticism.) See also John W. N. Watkins, “Against ‘Normal
Science’,” in Lakatos & Musgrave, eds., Criticism, pp. 25-37; and
J. O. Wisdom, “The Nature of ‘Normal’ Science,” in Schilpp, ed., The
Philosophy of Karl Popper, 2: 820-842, and Popper’s response to
Wisdom, “Replies,” 2: 1148-1153.
Kuhn argues that Popper’s interpretation of scientific method takes
characteristics of what, Kuhn calls “extraordinary” or “revolutionary”
science and applies them to the entire scientific enterprise, thus
overlooking the actual procedures and characteristics of what Kuhn calls
“normal” science. While he grants that Popper’s description of empirical
scientific method does apply in what Kuhn terms “crisis” situations
(situations in which an old, accepted theory has irretrievably broken
down, situations that give rise to “extraordinary” or “revolutionary”
science), he denies that Popper’s interpretation is a description of how
scientists normally proceed.
statements of Kuhn will give a sense of his criticism of Popper’s
“I suggest then that
Sir Karl has characterized the entire scientific enterprise in terms
that apply only to its occasional revolutionary parts. . . . neither
science nor the development of knowledge is likely to be understood if
research is viewed exclusively through the revolutions it occasionally
produces. For example, though testing of basic commitments occurs only
in extraordinary science, it is normal science that discloses both the
points to test and the manner of testing. . . . a careful look at the
scientific enterprise suggests that it is normal science, in which Sir
Karl’s sort of testing does not occur, rather than extraordinary science
which most nearly distinguishes science from other enterprises. If a
demarcation criterion exists (we must not, I think, seek a sharp or
decisive one), it may lie just in that part of science which Sir Karl
“The criteria with
which scientists determine the validity of an articulation or an
application of existing theory are not by themselves sufficient to
determine the choice between competing theories. Sir Karl has erred by
transferring selected characteristics of everyday research [e.g., logic]
to the occasional revolutionary episodes in which scientific advance is
most obvious and by thereafter ignoring the everyday enterprise
entirely. In particular, he has sought to resolve the problem of theory
choice during revolutions by logical criteria that are applicable in
full only when a theory can already be presupposed.” Kuhn, “Logic,” in
Schlipp, ed., The Philosophy of Karl Popper, 2: 802, 813 (in
Lakatos & Musgrave, eds., Criticism, pp. 6, 19).
Kuhn further argues
(quoting C.R., p. 51) that Popper’s programme actually
contains—though Popper does not recognize them as
such—”social-psychological imperatives” of the sort Kuhn thinks might
help to explain scientific choices made on bases other than logic and
experiment alone. See “Logic,” 2: 813-816 (in Lakatos & Musgrave, eds.,
Criticism, pp. 19-22). See also Kuhn’s “Reflections on My
Critics,” in Lakatos & Musgrave, eds., Criticism, pp. 231-278.
Popper, on the other hand, admits the actuality of what Kuhn calls
“normal” science, but regards it as a relatively recent phenomenon and
judges it to be a very real danger to science and the growth of
knowledge. Popper is convinced that he has described scientific method
as it ought to be practiced, and is of the opinion that a major disaster
would occur should a sociological criterion of science (such as Kuhn
proposes) ever replace a rational criterion (namely, Popper’s criterion
of demarcation: falsifiability).
See Popper, “Normal
Science and Its Dangers,” in Lakatos & Musgrave, eds., Criticism,
pp. 51-58, and “Replies,” 2: 1144-1148, both directed against Kuhn; and
compare with another statement (“Replies,” p. 1036): “I am inclined to
say that we should attempt to find out what [scientists] ‘ought’ to do.
This ‘ought’ is . . . the ‘ought’ of a hypothetical imperative. The
question is: ‘How should we proceed if we wish to contribute to the
growth of scientific knowledge?’. And the answer is: ‘You cannot do
better than proceed by the critical method of trial (conjecture) and the
elimination of error, by trying to test, or refute, your conjectures.’
The argument supporting this reply belongs to situational logic. I do
not think that we should turn to the (sociological) question of what
scientists actually do or say, except perhaps to refute certain
competing answers.” It is on this position that strong currents in the
contemporary philosophy of science are moving away from Popper’s
analysis, but also away from Kuhn’s. See Frederick Suppe, “Afterword,”
in Suppe, ed., The Structure of Scientific Theories, pp. 633-728,
especially pp. 643-649 on contemporary criticisms of Kuhn’s
“sociological” interpretation as extreme, and pp. 682-704 on the work of
Dudley Shapere, who is critical of the positions of both Popper and
I cannot hope to resolve this
controversy here, nor even to enter into the details of the discussion.
One of my purposes in alluding to it, however, is to illustrate that
within the community of philosophers of science there are fundamental
differences of opinion on the nature of scientific inquiry and its basic
method. While Popper is convinced that he is describing scientific
method at its best, others of his peers judge that he is ignoring
important aspects of how science is actually conducted. Moreover, this
disagreement over what the actuality of scientific method is does not
appear to be amenable to any final resolution. While all solutions thus
far proposed have been found wanting in some respect, arriving at an
adequate analysis of scientific method remains an open question in the
ongoing work of the philosophy of science community.
A number of years ago,
Langdon Gilkey noted that the interpretation of scientific inquiry is
actually an open question which has provoked a pluralism of
interpretations in the philosophy of science. .” . . when a theologian
becomes discouraged by the inability of theology to give a reasoned
defense or even a rationally articulated explication of the fundamental
terms of religious faith, it is some relief to find that philosophers of
science encounter the same inability, the same confusion, and the same
disagreements when they seek to understand precisely what it is that is
going on in scientific inquiry.” Religion and the Scientific Future
(New York: Harper & Row, 1970), p. 42. The developments in the
philosophy of science in the succeeding decade have only confirmed
and Growth of Objective Knowledge
The topic I must now consider is the
nature of the knowledge arrived at by science and other forms of
thought. Throughout his writings Popper characterizes all human
knowledge as hypothetical, but he also speaks of some knowledge as
objective. Since we have already seen in some detail why Popper regards
all knowledge as inherently hypothetical, in this subsection I will
restrict my attention to what Popper means by “objective knowledge.”
The term “objective knowledge” carries several related meanings in
Popper’s thought. Its initial meaning is the one he gives it in
discussing scientific objectivity: objective knowledge is knowledge
arrived at by faithfulness to the critical method and presented in a
form that remains open to the application of critical method. In The
Logic of Scientific Discovery Popper distinguishes between “our
subjective experiences or our feelings of conviction” and “the objective
logical relations” within scientific statements and between systems of
such statements. Objectivity concerns these objective relations, not
subjective feelings or expressions. Thus Popper says that “the
objectivity of scientific statements lies in the fact that they can
be inter-subjectively tested.”
[L.Sc.D., p. 44.]
By “objective knowledge,” then,
Popper does not mean knowledge that is true or certain; rather, he means
hypotheses, theories, conjectures, and universal statements formulated
in “public” language and open to critical analysis. It ought to be
noted that this definition of objectivity does not claim that only
scientific statements are objective; it does not exclude philosophy,
metaphysics, and so forth, from objective discourse. Just as Popper
insists that the criterion of falsifiability does not draw a line around
meaningful discourse but within it, so his definition of scientific
objectivity does riot draw a line around objective discourse but within
it. He generalizes the definition of objectivity to mean
“inter-subjective criticism,” or discourse that is open to
“mutual rational control by critical discussion.”
[Ibid., p. 44
note *1, and further references there.]
In this way he can argue that all human statements, when subject to this
general method of critical discussion, can be considered objective.
What distinguishes scientific objectivity is the more narrow definition
that scientific statements can be inter-subjectively tested
(i.e., they are able to be falsified). In either the special case of
science or the more general case of rational discussion, the basic
meaning of “objective knowledge” is the same: the theories, hypotheses,
and conjectures we formulate in public language and which we hold open
to critical analysis (or inter-subjective criticism).
Popper later developed this position
into a significant part of his philosophy.
[See especially “Epistemology Without a Knowing Subject,” and “On the
Theory of the Objective Mind,” both in Ob. Kn., pp. 106-152;
He argues that epistemology as well as common sense has overlooked
objective knowledge and “mistakenly took it for granted that there was
only one kind of knowledge—knowledge possessed by some knowing subject.
[Ob. Kn. p. 73] Popper, in contrast, distinguishes
between “subjective knowledge,” which he defines as consisting of “the
dispositions of organisms,” and “objective knowledge,” which he defines
as consisting of “the logical content of our theories, conjectures,
He then asserts that on
the basis of this distinction we may speak of three “worlds”:
first, the world of physical objects
or of physical states; secondly, the world of states of consciousness,
or of mental states, or perhaps of behavioural dispositions to act; and
thirdly, the world of objective contents of thought, especially of
scientific and poetic thoughts and works of art.
Ob. Kn., p. 106. See also
ibid., pp. 73-74. In several essays Popper refers to these as
the “first,” “second,” and “third” worlds, but he later changes the
terminology to “world 1,” “world 2,” and “world 3.” See ibid.,
p. 31 and “Autobio.,” pp. 143-149 and notes 7a and 293 on pp. 157 and
Popper calls these “world 1,” “world 2,” and “world 3” respectively, and
includes as some of the more important “inmates” of “world 3”
theoretical systems, problems, problem situations, critical arguments,
the state of a discussion or the state of a critical argument, and the
contents of books, journals, and libraries. He wants to argue against
the position that all of these entities are essentially (perhaps merely)
symbolic or linguistic
expressions of subjective mental states, or perhaps of behavioural
dispositions to act; further, that these entities are means of
communication—that is to say, symbolic or linguistic means to evoke
in others similar mental states or behavioural dispositions to act.
[See Ob. Kn., p. 107.]
Against this, Popper argues that “world 3” entities have an independent
existence of their own, “more or less” independent of “world 2.” The
major criticism he has of most epistemologies is that in attempting to
reduce the “world 3” entities to mere expressions or communications of
“world 2” states of consciousness, they miss precisely that which makes
objective knowledge objective, and so undercut that which makes it
possible to formulate criticism. The concentration on the “world 2”
states of consciousness undercuts the ground for the application of the
critical method of rational discussion.
See ibid., p.
31: .” . . only a formulated theory (in contradistinction to a
believed theory) can be objective, and . . . it is this formulation or
objectivity that makes criticism possible; [this led me] to my theory of
a ‘third world’ . . .”See ibid., pp. 108-150, 153-168 for his
arguments against classic epistemologies.
Criticism, Popper appears to argue, can have a firm basis only if we can
show that the objective knowledge of “world 3” is relatively independent
of subjective states of consciousness.
Popper’s argument on this issue is a
development of the positions he initially presented in The Logic of
Scientific Discovery. In a later work he presents the argument in
the form of three main theses, all of which are concerned with a proper
understanding of “objective knowledge.”
My first thesis involves the existence of two different
senses of knowledge or of thought: (1) knowledge or thought in the
subjective sense, consisting of a state of mind or of consciousness
or a disposition to behave or to react, and (2) knowledge or thought
in an objective sense, consisting of problems, theories, and
arguments as such. Knowledge in this objective sense is totally
independent of anybody’s claim to know; it is also independent of
anybody’s belief, or disposition to assent; or to assert, or to act.
Knowledge in the objective sense is knowledge without a knower:
it is knowledge without a knowing subject.
[Ob. Kn., pp. 108-109; see also pp. 115-119 on the
objectivity and autonomy of “world 3.”]
Popper’s second thesis is that epistemology, which he understands to be
“the theory of scientific knowledge,” [Ibid.,
p. 108] can be properly developed only if it restricts itself to
the study of objective knowledge, that is; the “largely autonomous”
“world 3,” instead of centering its attention on “world 2” subjective
states of consciousness.
[See ibid., p. 111]
His third thesis is that an
objectivist epistemology developed in this way will shed light on the
“world 2” subjective processes of understanding, but that the converse
is not the case. [See ibid., p. 112]
In other words, Popper argues that
one can only work out a cognitional theory after one has developed an
The theory of knowledge Popper discovers in his analysis
of the “inmates” of “world 3” is exactly the same as the theory
underlying all we have seen of his thought: that knowledge grows
according to the method of conjecture and refutation. Popper
generalizes and summarizes this theory (which he also calls the method
of problem solving) in the following schema: P1
P2, where P1 is the problem from which one starts,
TT (for “tentative theory”) is the proposed conjectural solution to P1,
EE (for “error elimination”) is the severe critical evaluation of the
proposed theory, and P2 is the problem situation as it
emerges from the initial attempt to resolve P1.
ibid., pp. 119, 121, 144, 164, 168, 243.] An
important point in Popper’s argument for the autonomy of “world 3” is
the observation that the contents of objective knowledge have
implications and tend to generate problems that were not foreseen by any
person. This leads Popper to assert that objective knowledge really has
a life of its own; it has logical relations and implications that do not
depend for their existence on their being thought by a knowing subject.
This is what he means when he says that objective knowledge is
knowledge without a knowing subject. It is a product of knowing
subjects, but it is autonomous. Popper’s favorite example is the
discovery of natural numbers. Once the theory of natural numbers is
produced by human subjects, it creates its own autonomous problems never
before entertained by a knowing subject and which are gradually
discovered. For example, the existence of prime numbers is discovered,
and the problem of whether the sequence of prime numbers is infinite
arises. This was not intended when the theory of natural numbers was
produced; it is an unintended consequence of the logical relations in
the “world 3” theory of natural numbers discovered as subjects operate
on and with the contents of this autonomous “world 3.” Objectivity,
then, has an ontological referent: the logical relations and
implications of the contents of “world 3.” These relations and
implications unfold according to the scheme Popper proposes: P1
P2. This is a schema for the growth of knowledge.
Once it is seen that objective knowledge is produced, is
related, unfolds, and grows according to this pattern, then it can be
seen that human understanding also follows this same pattern in the
basic method of problem-solving.
I might note here that Popper argues that this same pattern of
problem-solving can be detected in or used to interpret the whole of
biological evolution, so that human understanding and the growth of
knowledge is, while an immense achievement, a special case of an
activity common to all life. See ibid., pp. 113-115, 145-150,
241-255, 256-284; “Autobio. ,” pp. 141-143.
The subjective processes that occur in the human search
for understanding are all operations on and with “world 3” objects, and
objectivity in understanding means faithfulness to the method of
problem-solving (the critical method) or subjecting to rational
criticism all our proposed solutions to the problems we address.
[See Ob. Kn., pp.
162-168, and compare pp. 136-137.]
Thus Popper argues that the schema he proposes is not
only a schema of how knowledge grows (epistemology), but also an
analytic description of what we are doing when we try to understand
[See ibid., p. 165.]
This leads to two important observations. First, the world of objective
knowledge and its effect on us is really what is responsible for our
rationality: “we thus owe to the third world especially our
rationality—that is, our subjective mind, the practice of critical and
self-critical ways of thinking, and the corresponding dispositions.”
[Ibid., p. 147.]
Even more importantly, however, the interaction between
the autonomous world of objective knowledge and our subjective (“world
2”) search for understanding is the cause of our self-transcendence.
. . . I suggest that everything depends upon, the
give-and-take between ourselves and our work; upon the product which we
contribute to the third world, and upon that constant feed-back that can
be amplified by conscious self-criticism. The incredible thing about
life, evolution, and mental growth, is just this method of
give-and-take, this interaction between our actions and their results by
which we constantly transcend ourselves, our talents, our gifts. . . .
The process of learning, of the growth of subjective
knowledge, is always fundamentally the same. It is imaginative
criticism. This is how we transcend our local and temporal
environment by trying to think of circumstances beyond our
experience: by criticizing the universality, or the structural
necessity, of what may, to us, appear (or what philosophers may
describe) as the ‘given’ or as ‘habit’; by trying to find; construct,
invent, new situations—that is, test situations, critical
situations; and by trying to locate, detect, and challenge our
prejudices and habitual assumptions.
This is how we lift ourselves by our bootstraps out of
the morass of our ignorance; how we throw a rope into the air and then
swarm up it—if it gets any purchase, however, precarious, on any little
What makes our efforts differ from those of an animal or
of an amoeba is only that our rope may get a hold in a third world of
critical discussion: a world of language, of objective knowledge. This
makes it possible for us to discard some of our competing theories. [Ibid., pp. 147, 148; see p. 119.]
In this way the growth of subjective knowledge leads us
to self-transcendence, but this is possible only because our search for
understanding is related in every way and at every point to the
structure and growth of objective knowledge. It is the feed-back from
the autonomy and objectivity of “world 3” that enables our “world 2”
subjective cognitional process to be self-transcending.
This raises the question of the relationship between
Popper’s three worlds. Popper argues that “world 2”, the world of
subjective experience, is the mediating link between ‘world 1’ and
“world 3.” ‘World 1’ and “world 3” are liked only indirectly through the
mediation of the subject.
. . . all our actions in the first world are influenced
by our second world grasp of the third world. This is why it is
impossible to understand the human mind and the human self without
understanding the third world (the ‘objective mind’ or ‘spirit’); and
why it is impossible to interpret either the third world as a mere
expression of the second, or the second as the mere reflection of the
third. [Ibid., pp.
Popper wants to argue for “the objective reality of all
[Ibid., p. 156; see p. 155, and “Autobio.,” p. 147.]
with the world of the human subject (the mind) at the
pivot of articulation. Thus it is the reality of the objective and
autonomous “world 3”
[Ob. Kn., p. 185.]
that provokes or calls forth the self-transcendence of
the human subject in “world 2”, and at the same time it is the activity
of the human subject in “world 2” which produces “world 3” and also
enables “world 3” to affect physical reality (“world 1”). It is because
the world of human subjectivity is of such pivotal importance that
Popper stresses that the growth of subjective knowledge occurs only in
relation to objective knowledge and follows the same pattern of
As I mentioned above, Popper argues that the method of
growth he has described for both objective and subjective knowledge
applies to all forms of human thought. “Labouring the difference
between science and the humanities has long been a fashion, and has
become a bore. The method of problem solving, the method of conjecture
and refutation, is practised by both.”
[Ob. Kn., p.
Beyond such disciplined forms of thought as science and
the humanities, Popper argues the critical method of conjecture and
refutation is the method underlying all human knowledge, including
common sense, and can even be detected as the principal way in which all
life forms relate to their environments.
The method of learning by trial and error—of learning
from our mistakes—seems to be fundamentally the same whether it is
practised by lower or higher animals, by chimpanzees or by men of
science. My interest is not merely in the theory of scientific
knowledge, but rather in the theory of knowledge in general. Yet the
study of the growth of scientific knowledge is, I believe, the most
fruitful way of studying the growth of knowledge in general. For the
growth of scientific knowledge may be said to be the growth of ordinary
human knowledge writ large . . . .
C.R., p. 216. See also
L.Sc.D., pp. 15-23. For the development of this position into an
interpretation of biological evolution, see references in Thesis,
p. 152 note 1.
Popper is convinced that at root there is one basic
method shared by all forms of learning and governing the growth of all
forms of knowledge. Science is distinguished (or demarcated) from all
other forms of knowledge by the fact that its conjectures can be
empirically tested; that is, by the use of special methods empirical
science can subject its conjectures to empirical tests designed to
falsify them. But science shares its basic method, the critical method
of conjecture and refutation, with all other forms of thought and
Thus we may note how thoroughly Popper disagrees with the logical
positivist interpretation of science and other modes of thought. Not
only does Popper argue that the humanities have a legitimate claim to
speak meaningfully (Thesis, pp. 132-134), not only does he defend
the possibility of objectivity in non-scientific discourse (Thesis,
pp. 148-149), he also argues that non-scientific disciplines employ the
same general method as do the natural and physical sciences.
There is one topic I have not yet discussed which has
remained of central importance over Popper’s long career; the relation
of scientific knowledge and knowledge in general to truth. To state
Popper’s position in brief, he argues that while there must be objective
truth, we can never know if we have grasped the truth in any of our
conjectures. Yet the idea of truth and the desire and search for truth
play important heuristic and regulative roles in the growth of
knowledge. Moreover, there are ways in which the notion of truth can be
formalized so as to be of logical assistance in the testing of
conjectures in empirical science.
We find an early statement of this position at the end of
the main text of The Logic of Scientific Discovery:
Science is not a system of certain, or well-established,
statements nor is it a system which steadily advances towards a state of
finality. Our science is not knowledge (episteme); it can never
claim to have attained truth, or even a substitute for it, such as
. . . Although it can attain neither truth nor
probability, the striving for knowledge and the search for truth are
still the strongest motives of scientific discovery.
Shortly after this was written, Popper met Alfred Tarski,
who had developed a logical analysis Popper regards as a valid
rehabilitiation of the correspondence theory of truth (i.e., statements
are true if they correspond to the facts). Popper’s subsequent work was
deeply influenced by Tarski’s theory.
Popper has recounted in numerous places the influence on his
thought of Tarski’s theory. See “Autobio.,” pp. 78, 112-114; L.Sc.D.,
p. 274 note *1; C.R., pp. 223-227; Ob.Kn., pp. 44-51,
59-60, 314-318, 319-39.
It is beyond the scope of my study to enter into a
discussion of Tarski’s theory and its influence on Popper’s work, short
of noting that it is Tarski’s analysis that allows Popper to develop his
theory of verisimilitude, to argue on behalf of metaphysical realism,
and to speak of the idea of truth as an important regulative idea in the
growth of knowledge. I will restrict my comments here to Popper’s
argument for metaphysical realism and the idea of truth as a regulative
Popper agrees with idealism that all theories are our
constructs which we try to impose on the world of nature and our
experience. He departs from idealism, however, in holding that “the
question whether our man-made theories are true or not depends upon the
real facts; real facts which are, with very few exceptions, emphatically
[Ob. Kn., p. 328.]
How is it, though, “that we know there are “real facts”?
What is the evidence for arguing in support of realism? While such an
argument is in Popper’s classification metaphysical, not empirical,
Popper believes there is sound evidence for the realist position. The
evidence is found in the very ideas of error, mistakes, and fallibility.
“The very idea of error, or of doubt (in its normal straightforward
sense) implies the idea of an objective “truth which we may fall to
[C.R., p. 226.]
Thus the idea of truth acts as a regulative idea in our
search for understanding, and also implies the existence of a real world
independent of our thought processes and theories.
It is only the idea of truth which allows us to speak
sensibly of mistakes and of rational criticism, and which makes rational
discussion possible—that is to say, critical discussion in search of
mistakes with the serious purpose of eliminating as many of these
mistakes as we can, in order to get nearer to the truth. Thus the very
idea of error—and of fallibility—involves the idea of an objective truth
as the standard of which we may fall short. (It is in this sense that
the idea of truth is a regulative idea.)
Moreover, if we actually test a conjecture and succeed in
falsifying it, “we see very clearly that there was a reality—something
with which it could clash.
[Ibid., p. 166.]
Hence it is through falsification that we actually have
experience of reality.
Our falsifications thus indicate the points where we have
touched reality, as it were.
It is through the falsification of our suppositions that
we actually get in touch with “reality.” It is the discovery and
elimination of our errors which alone constitute that “positive”
experience which we gain from reality.
Ob. Kn., p. 360. Popper’s italics omitted. Popper thus holds
that while we can act in reality, while we can manipulate “world 1” and
affect it with our “world 3” theories in experiments and technology, we
can never be sure that we know reality. Our experience of reality gives
us no “positive” information except for the knowledge that our
conjectures and theories can be (and often are) erroneous. This does
not mean that we have no knowledge, but it does mean that all knowledge
must forever be hypothetical and severely limited in nature.
Popper summarizes his position in this way:
Theories are our own inventions, our own ideas; they are
not forced upon us, but are our self-made instruments of thought; this
has been clearly seen by the idealist. But some of these theories of
ours can clash with reality; and when they do, we know that there is a
reality; that there is something to remind us of the fact that our ideas
may be mistaken. And this is why the realist is right.
[C.R., p. 117.
For an extended treatment of realism see Ob. Kn., pp. 37-44.]
In sum, Popper argues on behalf of metaphysical realism
and the importance of the idea of truth, even though his conclusions
regarding the hypothetical character of all knowledge and the
impossibility of verifying any of our conjectures cause him to deny that
we can attain any certain knowledge. Our knowledge of reality, even in
the empirical sciences, always remains uncertain, conjectural, and
This does not mean, however, that there can be no
progress or growth in knowledge. Popper does not like to speak of the
growth of scientific knowledge as cumulative because in his opinion most
people will take that to mean the mistaken inductivist ideal of the
gradual accumulation of observations leading necessarily (if the
observer is patient enough) to the discovery of the laws of nature.
[See, e.g., L.Sc.D., pp. 279-280.]
He does, however, support the interpretation that there
is progress and growth in scientific knowledge. To be sure, Popper is
no naive progressivist and is under no illusion that progress is
inevitable and certain.
[See C.R., pp. 215-216.]
Yet, he insists, the method of science does enable
progress to be made if scientists are faithful to the demands of that
method. Popper usually prefers to characterize the growth or progress
of scientific knowledge as growth by means of criticism, or growth by
the “revolutionary” method of the overthrow (refutation) of false
theories and the construction of new, better theories.
[See, e.g., ibid.,
pp. 129, 215-216.]
The model Popper proposes is actually a cumulative model
(so long as one does not interpret this in the Baconian inductivist
sense): “our latest and best theory is always an attempt to incorporate
all the falsifications ever found in the field, by explaining them in
the simplest way . . . .”
[Ibid., pp. 116-117.]
The present state of scientific knowledge (that is to
say, the present state of scientific opinion) is always built on the
past, and occurs in the context of a scientific tradition. The growth
and progress, however, is never automatic; it depends on taking the risk
of bold conjecturing and the risk of severe criticism of those
If we can never know the truth with certainty, the major
question that arises is: how, then, do we know that we are making
progress toward the truth? By what criteria are we able to judge that
our new conjectures are “better,” that they are closer approximations to
the truth? Popper wants to argue that we have more than subjective
(“world 2”) conviction to support the idea of progress toward truth. As
we will see in the next subsection, Popper argues that it is possible to
develop objective criteria of progress toward truth even in metaphysical
discussions, but it is in arguing this position for the empirical
sciences that he develops a good part of his philosophy of science.
Popper argues that his theories of testability and verisimilitude
provide the criteria for the appraisal of theories, criteria that enable
us to recognize (objectively) that one theory is a better approximation
to the truth than another.
For a good short statement of this position, see Ob. Kn.,
pp. 143-145. For a more detailed argument see ibid., pp. 47-60,
304-318, 319-335; and C.R. Chapter 10 “Truth Rationality and the
Growth of Scientific Knowledge,” pp. 215-250, esp. pp. 228-236; 240-248.
It is here, particularly with regard to the develop-ment
of the theory of verisimilitude, that Tarski’s work has been so
influential on Popper. I need not enter into a discussion of this part
of Popper’s work, interesting though it is. For my purposes, it is
enough to observe that Popper argues for objective criteria for judging
progress in the growth of knowledge and that all these criteria are
connected to the criticism or testing of conjectures and theories.
Popper summarizes his position well in the following passage:
. . . one great advantage of the theory of objective or
absolute truth [i.e., truth as correspondence with the facts] is that it
allows us to say . . . that we search for truth, but may not know when
we have found it; that we have no criterion of truth, but are
nevertheless guided by the idea of truth as a regulative principle .
. . ; and that, though there are no general criteria by which we can
recognize truth—except perhaps tautological truth—there are something
like criteria of progress towards truth . . .
[C. R., p.
Metaphysics and Its Relation to Science
As I discussed above, Popper has from the beginning
rejected any attempt to characterize metaphysics as meaningless. The
line of demarcation between science and metaphysics is not an impassable
wall or an unbridgable gulf. Rather, the line of demarcation marks the
point, more or less clear, at which our discourse becomes empirical
(which for Popper, we recall, means testable). The reason Popper
refused to dismiss metaphysics as meaningless is that very often in the
past metaphysical ideas have been the forerunners of scientific
. . . most of our scientific theories originate in myths.
The Copernican system, for example, was inspired by a Neo-Platonic
worship of the light of the Sun who has to occupy the “centre” because
of his nobility. This indicates how myths may develop testable
components. They may, in the course of discussion, become fruitful and
important for science. In my Logic of Scientific Discovery I
gave several examples of myths which have become most important for
science, among them atomism and the corpuscular theory of light. It
would hardly contribute to clarity if we were to say that these theories
are non-sensical gibberish in one stage of their development, and then
suddenly become good sense in another.
[Ibid., p. 257;
see L.Sc.D., pp. 277-278.]
Moreover, the scientific quest for knowledge is inspired
and guided by convictions that Popper must classify as metaphysical.
Science and the quest for knowledge, Popper held; depend on “the
unscientific, the metaphysical . . . faith in laws, in regularities
which we can uncover—discover.”
278; see also pp. 252-253.]
Metaphysics, then, cannot be meaningless, and is even of
positive value for science: it is very often a source for interpretative
ideas that in the course of time can become testable, and it is the
source of our faith and conviction that science is possible, that there
are regularities to be discovered.
It might be helpful to recall that Popper’s use of the word
“metaphysics” is much broader than its customary designation of a
particular sub-discipline of philosophy. By “metaphysics” Popper means
all non-testable forms of thought, including religion, art, poetry, etc.
In The Logic of Scientific Discovery Popper was of
the opinion that metaphysics is entirely subjective, or to use his later
terminology, that all of metaphysics is in “world 2” and not subject to
critical discussion. The limits of arguability, he believed, coincide
with the limits of science. He later decided, however, that he was
wrong on this point, and argued that although metaphysical theories are
non-testable (i.e. irrefutable and hence nonscientific), they may be
rationally and critically discussed. [See Ob. Kn.,
p. 40 note 9.]
Although Popper does not say this, his position on the
arguability of metaphysical theories seems to be a consequence of his
broadening of the notion of objectivity from inter-subjective testing to
inter-subjective criticism (see Thesis, pp. 148-149). The
connection seems clear.
His argument runs as follows.
[See ibid., pp.
If we accept the criterion of demarcation (or, as Popper
calls it in this place, the criterion of refutability), then
metaphysical theories are irrefutable by definition: their statements
are such that they cannot be empirically tested. They are compatible
with any given empirical state of affairs, and they cannot predict an
empirical state of affairs which would be incompatible with the theory.
For an interesting, if brief, application of the criterion to the
psychoanalytic theories of Freud and Adler, see “Replies,” pp. 984-985.
Such theories, in Popper’s analysis, can neither be
proven nor disproven: they share with all theories the inability to be
verified, but they differ from scientific theories in that they also
cannot be falsified. Yet, Popper argues, there can be rational,
critical discussions of these metaphysical theories which allow us to
conclude that some of these theories are false and others better
approximations to the truth. How is it possible to argue rationally
(critically) about theories which we know to be neither demonstrable nor
refutable? How can we conclude that a metaphysical theory is false when
it is impossible actually to falsify it? Popper’s solution is to point
out that metaphysical theories are not isolated assertions about the
world but rather are developed in a context: they address problems and
are designed to resolve those problems. Popper calls this context the
“problem-situation” and argues that critical discussion of metaphysical
theories can occur if we direct attention to the problem situation.
. . . every rational theory, no matter whether
scientific or philosophical, is rational in so far as it tries to
solve certain problems. A theory is comprehensive and reasonable
only in its relation to a given problem-situation, and it can be
rationally discussed only by discussing this relation.
[C. R., p.
When attention is directed to the problem and the problem
situation, it is then possible to ask about the theory such questions
Does it solve the problem? Does it solve it better than
other theories? Has it perhaps merely shifted the problem? Is the
solution simple? Is it fruitful? Does it perhaps contradict other
philosophical theories needed for solving other problems?
Such questions constitute the criteria of critical
discussion and progress toward truth in nonscientific or metaphysical
Popper is thus arguing that something like a theory of
preference can be applied to critical discussions of nonscientific
theories. For example, in studying Hume’s philosophy, we might
characterize its problem as the grounding of realism; and we might note
that Hume’s conclusions led to an idealism because he was unable to
ground realism in his sensationalist theory of perception, learning, and
knowledge. It is then reasonable, Popper argues, to criticize Hume’s
It is more
customary to characterize Hume’s position as radical skepticism, but Popper speaks
of Hume’s “idealism.” See Ibid.
by pointing out the inadequacies of his theory of
learning and knowledge and, by judging that there exist “less
inadequate” theories of learning and knowledge which do not lead to
Popper clearly has his own theory of learning in mind. See
Thesis, pp. 128-129.
conclude that Hume’s idealism is false and metaphysical
realism is a better approximation to the truth.
For similar criticisms of determinism and irrationalism, see
C. R., pp. 199-200.
Thus even though all metaphysical theories are by
definition irrefutable, it is nevertheless possible by attention to the
problem situation to carry on rational and critical discussions which
can conclude that some metaphysical theories are false (though this
cannot be demonstrated ) empirically and others are less inadequate
approximations to the truth.
Popper does not develop his position any further. For instance,
apart from the critical questions he asks, he does not suggest any
specific criteria by which one might judge a metaphysical theory
“false,” and propose another as less inadequate. Still, Popper’s
position does imply that it is possible to formulate arguments of
“relative adequacy” or at least “relative inadequacy.”
Popper summarizes his position in this way:
The discovery of a philosophical problem can be something
final; it is made once, and for all time. But the solution of a
philosophical problem is never final. It cannot be based upon a final
proof or upon a final refutation: this is a consequence of the
irrefutability of philosophical theories. . . . Yet it may be based upon
the conscientious and critical examination of a problem-situation and
its underlying assumptions, and of the various possible ways of
[C. R., p.
There is one other development in Popper’s estimation of
metaphysics which is of some interest for my topic. In the early
1950’s, in a work that remained unpublished until quite recently,
“Postscript: After Twenty Years.” This work, in galley proofs
since 1957, has been circulated and has had much influence in Popper’s
circle. See “Autobio.,” pp. 118-120. A quotation relevant to the topic
in the text is given in Lakatos and Musgrave, eds., Criticism, p.
183 note 3. This work has recently been published as Karl Popper,
The Postscript to the Logic of Scientific Discovery, ed. W. W.
Bartley, 3 vols., Totawa, N.J.: Rowman and Littlefield, 1982), Vol. 1:
The Open Universe: An Argument for Indeterminism; Vol. 2:
Quantum Theory and the Schism in Physics; Vol. 3: Realism and the
Aim of Science.
Popper described and analyzed the role played by what he
calls “metaphysical research programmes”, that is, metaphysical theories
and world-views that guide and influence the development of science. In
the course of his analysis, and by means of historical examples, Popper
argued that the changes in our ideas of what constitutes a satisfactory
explanation in science have been mediated by these metaphysical research
programmes. These ideas changed and developed over the ages under the
pressure of criticism, and even though such ideas are not testable, they
have been of great importance in the development of science. This has
led Popper to propose his own metaphysical view of the world and a
correlative research programme,
[See "Autobio.," pp. 120, 133-143; and Obj. Kn., Chapters 6 & 7, pp.
but what is of interest for my topic is
Popper’s recognition of the role of metaphysics in the explanation of
explanation. By this I mean that apparently Popper would agree with
Whitehead and Lonergan that one of the functions of metaphysics is to
explain how it is that the sciences can explain. At the very least,
Popper is arguing that the changes in metaphysical worldview can affect
what scientists accept as constituting a satisfactory explanation of the
Chapter II: The Tenability of Whitehead’s and Lonergan’s
Interpretations of Empirical Scientific Method:
Michael Polanyi on Scientific Method and Knowledge
Table of Contents