My responses to David Papineau are in RED.
Intellectual reputations are changeable. Thinkers who are revered during their
lifetimes are often forgotten afterwards.
In the late sixteeenth century the French philosopher Peter Ramus was
widely acclaimed as the greatest logician since Aristotle, and most Victorians
regarded the polymathic Herbert Spencer as the prime genius of their age. But now these two are now quite unread, and
appear only as footnotes in historical surveys.
During his lifetime Sir Karl Popper was as revered it is
possible for a philosopher to be. In
addition to his many academic accolades, he was knighted in 1965 and made a
Companion of Honour in 1982. He had the
rare distinction of election as a Fellow both to the Royal Society and the
British Academy.
Popper was always an outsider in
academic philosophy and his contemporaries at Oxford and Cambridge actively
opposed him being offered a post at either of those universities, even though
Popper was by far the best philosopher of his generation.
However, there is room to doubt that this standing will long
outlast him. Indeed, it is already
becoming difficult to understand exactly how Popper acquired his renown.
In large part Popper's eminence as a public figure stems
from his political works, The Open Society and its Enemies (1945) and The
Poverty of Historicism (1957). These
were passionate defences of social democracy against the twins threats of fascism
and communism. For all the virtues of
social democracy, it is not often associated with passion, and many
middle-of-the-roaders in the Butskellite years found Popper's fervour a welcome
source of excitement. Even so, few of
his supporters would argue that that his political writings alone justify the
stature of a major philosopher. If they
are important, it is because they express the political credo of a philosopher
of science who has shown us a new way to think about the relation between
theory and reality.
Popper is usually described as an
important philosopher of science but this neglects his equally significant
contributions to political theory and epistemology as the solver of the problem
of induction.
In The Logic of Scientific Discovery (1957, originally Logik
der Forschung, 1934), Conjectures and Refutations (1963), and Objective
Knowledge (1972), Popper develops an analysis of science which breaks radically
with previous views. If this analysis
were right, it would have significant implications for most aspects of our
intellectual life. Unfortunately, it does not stand up to examination.
Popper’s ideas are as intellectually
vibrant today as when he originally conceived them almost a hundred years ago.
If anything, he was ahead of his time.
Popper's philosophy of science centres on his rejection of
inductive reasoning. This is the kind of
reasoning by which we judge that some hitherto observed pattern will continue
to hold good in the future.
We should instead think that a
hitherto observed pattern will continue to hold good if and only if we have a
good explanatory theory of why it will continue to hold good.
Popper objects that all such inferences are logically
flawed, since nothing guarantees that the future will be like the past.
A good explanatory theory is the
only reason to think the future will resemble the past and it will never guarantee
it.
Moreover, he argues that inductive reasoning is discredited
by the history of science, since the characteristic fate of scientific
theories, from Ptolemy to Newton, has been failure.
No he argues that inductive
reasoning is logically invalid, not that failures in science show it is
invalid.
For Popper, these failures of induction do not demean
science itself.
…because induction plays no part in
good science…
This is because he views science as an essentially conjectural
activity. On the conventional view of
science, theories are derived inductively from past observations. Popper turns this conventional view of
science on its head. Rather than
starting with past observations, scientists first propose their theories as
conjectures, and then try to test them against experience. If the theories pass these tests, they
survive as conjectures. But if they
fail, they must be rejected, and replaced by new conjectures.
At first blush, this vision of science can seem
attractive. Popperian science is
dynamic, yet free from any taint of induction.
However, there is an obvious flaw.
Popper's falsificationist strategy of conjectures and refutations can
only deliver negative knowledge. It
shows certain scientific theories are false, but it never shows that any theory
is true.
Why would that be a flaw if that is
the only kind of scientific knowledge that has ever existed? Science has been
spectacularly successful in creating good explanations and allowing fast
technological progress but this hasn’t depended on the creation of certain
knowledge.
Popper is driven to this denial of positive scientific
knowledge by his rejection of induction.
But the denial is hard to take seriously. Nobody properly acquainted with the evidence
doubts that cigarettes cause lung cancer, or that matter is made of atoms.
It seems astonishing that a
philosopher should think nobody could express doubt about these things when
modern philosophy begins with Descartes. A modern take on such doubt would be
to wonder if the physical world is a computer simulation – if it was then
matter would not be made of atoms, nor could cigarettes be the cause of lung
cancer. It is not the evidence that forces us to believe in these things but
rather the success of the explanatory theory.
Science is a many-sided institution, and not all its
deliverances deserve equal respect. But
something is wrong with a philosophy that tells us that science can never yield
any positive findings.
No good arguments have been given to
show that this philosophy is wrong…
In retrospect,
Popper's falsificationism can be seen as an over-reaction to the demise of
classical physics at the turn of this century.
The replacement of Newton's physics by Einstein's was a great surprise,
and showed that the evidence underpinning the classical edifice was far less
firm that everybody had supposed.
Popper's mistake, however, was to condemn all inductive reasoning for
this failure. Maybe inductive evidence
will never suffice to lay bare the large-scale structure of space-time, or the
other fundamental secrets of the cosmos.
But this does not mean that it can never identify such more mundane
facts as that cigarettes cause cancer.
The explanatory theory that
cigarettes cause cancer is a good one and is open to falsification.
It is true that induction presents an abstract philosophical
puzzle. Inductive inferences are not
logically compelling, and because of this their ultimate authority is an issue
of philosophical controversy. But this
is a puzzle, not the start of a philosophical system. It is akin to the question "How do I
know there is a table in front of me?"
This is a good issue for first-year philosophy students to cut their
teeth on. But outside the classroom
nobody seriously doubts that we do know about tables, and it is just as
unserious for Popper to doubt that we know that smoking causes cancer.
The reason I know that there is a
table in front of me is that I have a good explanatory theory involving atoms
coming together in a way that appears in my consciousness as a solid piece of
furniture as a result of the way light is reflected off the table surface and
in to the photosensitive cells at the back of my eyes. If I had good reason to
doubt any of that, I would have good reason to doubt the table.
It is sometimes said
that even if Popper is wrong about induction, he still does a good job of
"demarcating" the difference between science and non-science. Popper's answer to this "problem of
demarcation" is that proper sciences, unlike "pseudo-sciences" such
as astrology or phrenology, are distinguished by their falsifiability. They are precisely enough formulated to yield
definite predictions against which they can be tested.
However, this
"problem of demarcation" is not a genuine problem, but entirely of
Popper's own making. The real difference
between the atomic theory of matter, say, and astrology, is that the atomic
theory is firmly established by a large amount of evidence, whereas astrology
is mere speculation.
If an astrologer were to accept an
empirical test of whether their predictive theory was accurate, it would be a
scientific theory, though a very bad one, because it would have low explanatory
content. Atomic theory is a good scientific theory because it is hard to vary
and has high explanatory content. It has also survived many empirical tests,
but the number of empirical tests that it has survived does not increase the
probability that it is a true theory.
This is what most non-philosophers would say, and they would
be quite right. But Popper cannot say
this, because he thinks that inductive evidence is impotent. So he is forced to regard the atomic theory
as no less speculative than astrology, and is stuck with the non-problem of
explaining why some speculations are better than others.
Popper would say both theories are
speculative but that atomic theory is a better theory because it offers more
scope for empirical falsification.
Despite these
manifest failings, Popper's falsificationism is popular among practising
scientists. The reason is probably that
Popper's story best fits science at the cutting edge of research.
What makes your reason “probable” as
opposed to just being true or false?
Most new ideas at the limits of knowledge do start life as
pure speculations, and it is true that they are distinguished from the musings
of madmen only by the precision which allows them to yield definite
predictions.
All ideas start life as speculations,
including the idea that there is a table in front of me. The musings of madmen
are usually different to those of science and philosophy because the latter, if
they are good, yield explanatory content. The precision with which a scientific
theory yields predictions is not the only criteria on which to judge it –
instrumentalism is false.
By focusing exclusively on this aspect of science, Popper
creates the impression that all scientists, however workaday, are creative
visionaries with minds of steel.
Popper makes no claim about the
infallibility of scientists. Quite the contrary.
But speculative research is not the only kind of science, or
even the most important kind. There
would be no point to science unless its conjectures sometimes acquired enough
inductive evidence to graduate to the status of established truths.
Progress does not depend on
knowledge becoming certain truth and it never relies on “inductive evidence”.
This is the real reason for testing hypotheses against
predictions. The aim is not to falsify
them, but to identify those that can be turned into the kind of positive
knowledge that enables us to build bridges and treat diseases.
Theories that are falsifiable but
resist falsification and have high explanatory content are precisely those that
allow us to build bridges and treat diseases. Finding more and more reasons to
think a theory is true is unlikely to improve the theory but seeking to falsify
a theory might result in a theory being discarded in favour of a better theory.
Scientists who follow Popper in emphasising speculation over
evidence are like architects who admire the aesthetic use of new materials, but
don't care if the building leaks.
Popper would be focussed on finding
potential problems with a building and solving the problems.
We can see why they find innovation exciting. But they have lost their intellectual
moorings if they think that originality for its own sake is the point of their
profession.
Popper advocates progress through
problem solving, not originality for its own sake.
None of these criticisms of Popper's philosophy of science
are new. They have been well-known among
professional philosophers for over half a century. However, Popper has never given straight
answers to the objections.
Popper has given straight answers to
the objections to anyone who has taken the time to read him.
Instead he reassures his readers of the importance of his
views, while throwing up various smokescreens to hide their deficiencies.
This is ad-hominem attack on Popper.
One of Popper's strategies is to use words in a way which
make his views seem far more sensible than they are. The Australian philosopher David Stove has
pointed out (Popper and After, reviewed in the TLS, July 1 1983) that Popper
characteristically talks about scientific "knowledge",
"discovery" and "progress", even though his views imply
there are no such things.
Popper’s views do not imply that
knowledge, discovery and progress are impossible.
In the normal sense of these words, we can only know or
discover what we have reason to believe is true.
Knowledge does not imply either
belief (knowledge might be in a book) or certain truth (which is unobtainable).
Popper's official doctrine is that we never have any reason
to believe that any scientific theory is true, but his non-standard usage often
serves to obscure this from the less than fully attentive reader.
A scientist or philosopher does not have to
believe that their own theories are true.
Another ploy is to refuse to engage with his critics.
Popper did engage with his critics,
most famously with Wittgenstein who stormed off.
Throughout his career Popper belittled other professional
philosophers for their finicky concern with definitions.
Popper was a methodological
nominalist and recognised that no useful knowledge could come of arguing about
the definition of words, for example, a puppy is what I call a young dog – don’t
bother asking whether a puppy really is a young dog.
He was certainly right to condemn much modern academic
philosophy for its scholastic introspection.
But modern philosophy is not all bad, and in particular its criticisms
of Popper deserve answers.
Ironically part of the reason that much
academic philosophy is bad is that it lacks the error correcting mechanisms
associated with science which is the core of Popper’s philosophy of science.
Academic philosophers often compound the mistakes of their predecessors without
realising that they are mistakes.
One unfortunate result of Popper's self-imposed intellectual
quarantine is that the tradition in philosophy of science that he founded is
slowly having to relearn many of the basic philosophical truths that were
omitted from its curriculum.
When Popper does offer
arguments, they are not always strong.
One of his objections to inductive reasoning is that it militates
against bold theories of wide scope, since a wide-ranging theory is harder to
confirm inductively than a more cautious and limited one. This argument has often been repeated, even
though it did not take his opponents long to respond that it mixes chalk with
cheese. Boldness and inductive
confirmation are both important desiderata, and the fact they pull against each
other is not a good reason for discarding the one for the other.
Popper’s objection to inductive
reasoning was that it was logically invalid, not that is militated again bold
theories of wide scope. The reason a bold conjecture is better than a limited
one is that it contains greater explanatory content and more opportunity for
falsification.
Another favourite Popperian argument against induction
reasoning is that it focuses on support for subjective psychological states
like belief, and so is of no importance to the objective realm of scientific
methodology. But once more the
repetition of this argument owes more to Popper's personality than to
reason. It is true that beliefs are subjective
states, but questions about which beliefs ought to be held are as objective as
any other normative questions.
Popper was an advocate of seeking objective
moral truth in the same way as he advocated seeking objective scientific truth
(though never being certain in either case). What people “ought” to believe is
never logically derivable from what is the case, but there are good moral
conjectures about the objective fact of how one should live and bad ones and only
argument can distinguish between them. Whether someone subjectively believes or
disbelieves a moral conjecture has no bearing whatsoever on whether a moral
conjecture is a good one.
Towards the end of his career Popper inflated this jibe
about the subjectivity of beliefs into an overarching metaphysical system. He postulated an interlinked universe of
three worlds: the world of physics, the
world of subjective psychological states, and the objective world of knowledge,
theories, arguments, and problems. These
three worlds are quite distinct, in that none reduces to any other, but at the
same time each can influence the others.
Knowledge and the Body-Mind Problem is largely concerned
with this system of worlds. The book is
a version of a lecture series delivered by Popper at Emory University in 1969,
complete with a transcript of a question-and-answer session from the end of
each lecture. If the transcripts are a
fair sample, Popper's non-specialist audience let him off lightly. Even Popper's own followers regarded his
three worlds as cranky. The discussion
in this volume betrays some of the effects of his intellectual isolation. He does not seem to understand the workings
of alternative views, and the arguments he gives in favour of the three-world
system could be countered by nay well-trained philosophy undergraduate.
Why not give an example of a
counter-argument?
Both of the books under review are derived from the archive
of Popper's papers now held at Stanford University. The Myth of the Framework is a more
substantial volume, gathering together nine essays, mostly first published in
the 1970s and 80s. In the course of
these essays, Popper touches on a number of topics, and his comments on
biology, the social sciences and the history of philosophy are worth
having. Most of these essays are not
easily accessible in their original places of publication, and it is a service
to have them gathered in one volume.
The overall impression created by this volume, however, is
not entirely pleasing. A constant theme
running through these papers is the importance of free discussion and
open-mindedness. Popper is of course
right to emphasize these matters. But he
is wrong to suggest that they are the special property of his falsificationism.
Falsificationism is a methodological
technique that demarcates science from non-science. He nowhere limits
philosophical discussion to topics concerned with falsifiable statements and to
think he did is to confuse his philosophy with logical positivism of which he
was the leading critic.
Those who oppose
Popper by seeking positive truths in science have just as much reason, If not
more, to insist on the importance of critical discussion, and Popper has no
basis for his accusation that these opponents are all dogmatic authoritarians.
To believe that the truth is
manifest and that certainty is in human reach inevitably ends in
authoritarianism.
The survival of
critical standards in the modern academy is by no means assured, and the fight
to preserve them needs every support. It
does not help the defence of these standards if their most prominent
twentieth-century proponent failed to uphold them in his own intellectual
practice. Popper preached the importance
of open debate and recognition of error, but throughout his intellectual career
he fought to insulate a discredited idea against any possible criticism. Perhaps it would be best now if we remember
what Popper preached, and lay the rest of his doctrines quietly to rest.
The whole point of Popper’s philosophy
was to point the way to scientific, philosophical, political and ethical
progress and to highlight the intellectual currents that prevent progress. He
was the first to admit that the ideas we need to subject to critical
rationalism included his own.