The connection between philosophy and the
mathematical sciences has always been very close. Plato had written over the door
of his academy the words: "Let no one into here who
is ignorant of geometry". It was Aristotle who codified the
basic sciences into the categories and gave them the names
that we use to this day. Some of the greatest philosophers have
been themselves great mathematicians who invented new branches of mathematics. Descartes is an obvious example, and so is Leibniz
and Pascal. In fact, most of the great philosophers, not all, but most, came to philosophy from
mathematics or the sciences. And this tendency has continued into our present century. Bertrand
Russell was trained first as a mathematician. Wittgenstein was trained first as an engineer.
The reason for this persisting connection is I think obvious, and that is that the basic
urge which has driven most of the greatest philosophers has been the urge to deepen our
understanding of the world and of its structure. And this is also what creative scientists
are doing. For most of the past, too, people thought that mathematics was the most
indubitable knowledge as well as being utterly precise and clear that human beings possessed. So
there have always been plenty of philosophers examining mathematics to try & find out what
was so special about it, and whether this was something that could be applied to the acquisition
of other sorts of knowledge. Ditto with the sciences, which were also thought to yield a very
specially safe and certain kind of knowledge. What was it about science that made its results
so reliable? And could its methods, whatever these were, be used in other fields? These
investigations into the concepts and methods, procedures and models that are involved in
mathematics & science have come to be known as the philosophy of mathematics and the
philosophy of science. And it’s with these that we're going to be concerned in this program.
Chiefly, with the philosophy of science, though in fact, we have someone taking part who
is expert in both: Professor Hilary Putnam of Harvard University. Professor Putnam, I'd
like to start our discussion from a standpoint which I think a very large number of our viewers
occupy anyway, and it's really this. Since the 17th century I suppose, there's been a spectacular
decline in religious belief, especially in the west and especially among educated people.
And for millions, the role that used to be taken in life by a worldview based on religion
has been increasingly supplanted by a worldview based on science or at least purporting to
be derived from science, anyway. And this is still enormously powerful in the hold that
it has on people's minds throughout the west, probably it effects all of us. So I think I'd
like to start this discussion by getting you to pin-down that scientific world outlook
which is so influential in the modern world which will be underlying a lot of what we're going
to have to talk about. Let me dodge the question a little bit by talking not about scientists
think now but what many scientists thought 100 years ago or 75 years ago. Think of
doing a crossword puzzle. You might have to change a few things as you go along,
but towards the end, everything fits and things get added on one step at a time. That's the
way the progress of science looked for 300 years. In 1900, a famous mathematician, David
Hilbert, gave a list of 50 mathematical problems to a world congress of mathematicians which
are still very famous. And it's very interesting that he included one problem which we would
not call a mathematical problem very early in the list (I think problem 3) which was to put
the foundations of physics on a satisfactory basis. And that was for mathematicians, not for
physicists! The idea's---tiny it up. That's right. The idea is Newton, Maxwell, Dalton, and
so on, had all put in all the parts of the story, and now it was just for mathematicians
to basically clean up the logic, as it were. I think in a conversation we had a couple of days
ago, you described this as a "treasure chest" view, and I like that picture, because here's
this big chest that we're just filling up. It's an accumulation. You don't have to subtract,
you don't have to take out. Occasionally you make a little mistake, but basically the idea is
-- or to shift the metaphor -- like building a pyramid: you put down the ground floor,
then the next floor, and the next floor, it just goes up. That's part of this, a view
of knowledge as growing by accumulation. The other part of it is the idea that the special
success of the sciences -- obviously what we're impressed by is success. This culture values
success and science is a successful institution. But there's the idea that science owes
its success to using a special method and that comes partly from the history of science,
from the fact Newton, for example, lived after Bacon and was influenced by Bacon. And the idea
that empirical science has grown up together with something called "inductive logic". And this
idea that there's a method, the inductive method, and that the sciences can be characterized
by the fact that they use this method and use it explicitly and consciously, as it were,
not unconsciously as maybe someone who's learning cooking might be using it, but pretty
deliberately and explicitly. So I think that these two things, the idea of knowledge as
growing by accumulation & growing by the use of a special method, the inductive method,
are the key elements of the old view. Yes, and if I were going to put the same thing
I suppose slightly differently, I think I'd say this: For two or three hundred years, educated western
man thought of the universe and everything in it as consistently of matter in motion. And that
was all there was, whether from the outermost galaxies of the stars into ourselves and our
bodies, and the cells of which we're made up, and so on. And that science was finding
out more and more about this matter and its structure and its motion by a method which
you just characterized as "scientific method". And the idea was that if we went on long enough,
we'd simply -- as you said with your crossword puzzle metaphor -- we'd find out everything
there was to find out. We could, eventually, by scientific methods, completely explain
and understand the world. Now, that has been abandoned by scientists, though, in fact,
this hasn't got through yet to the non-scientist. There are still large numbers of
non-scientists who go on thinking that that's how scientists think, but of course, they no
longer do, do they? This has started to break down. I think it started to break down with Einstein. If I
can drag in a bit of history of philosophy, screaming by the hair: Kant did something in philosophy
which I think has begun to happen now in science. He challenged a certain view of truth. Before Kant
no philosopher really doubted that truth was simply correspondence to reality -- there are different
words, some philosophers spoke of "agreement". But the idea is a "mirror theory" of knowledge... Well Kant said it isn't so simple, there's a
contribution of the thinking mind. Sure, it isn't made up by the mind, Kant was no
Idealist; it isn't all a fiction, it isn't something we make up, but it isn't just a copy either.
What we call "truth" depends both on what there is, on the way things are, and on the
contribution of the thinker, the mind. I think that today scientists have come to a somewhat
similar view. That is, since the beginning of the 20th century, the idea that there's a
human contribution, a mental contribution to what we call "truth"; the theories aren't
simply dictated to us by the facts, as it were. I'd like to ask you to unpack that a little
because I think that some of our viewers will find this idea a little puzzling. "How can
it be" some people will ask themselves, "that what is and is not true could depend not only
on what the facts are, but on the human mind?" Well, let me use an analogy with vision. We
tend to think that what we see just depends on what's out there. But the more one studies
vision, either as a scientist or as a painter, one discovers that what's called vision
involves an enormous amount of interpretation. The color we see as red is not the same color
in terms of wavelengths at different times of the day. So that even in what we think of
as our simplest transaction with the world, just looking at it, we are interpreting. In other
words, we bring a whole number of things to the world that we're not directly conscious of
usually unless we turn inwards & start examining them. That's right. I think the world must've
looked different in the Middle Ages to someone who looked up and thought of the
stars as "up" and us at the bottom, for example. Today when we look out into space, I think
we have a different experience than somebody with the Medieval worldview. And what you're
saying is that the very categories in which we see the world & interpret our experience, and the
ideas within which we organize our observations and the facts around us and so on, are provided
by us. So that the world as conceived by science is partly contributed by external facts,
but also partly contributed by categories and ways of seeing things which come
from the human observer. That's right. And an example of that in science--I'll oversimplify, but
it's not basically falsified--is this wave-particle business. It's not that there's something, an electron,
which is some half a wave and half a particle, that would be meaningless. But that
there are many experiments which can be described two ways. You can either think
of the electron as a wave or you can think of it as a particle, and both descriptions
are in some crazy way true and adequate. They're alternative ways of describing the same
facts and both descriptions are accurate? That's right. Philosophers have started talking of 'equivalent
descriptions'. That's a term used in philosophy of science. But now, for a couple of hundred
years after Newton, educated western man thought that what Newton had produced was objective
fact and he had discovered laws which governed the workings of the world and the workings
of the universe, and this was just objectively true independently of us; that Newton and
other scientists had read these facts off of nature by observing it, and looking at it, and so on.
And these statements which made up science were simply true. Now, there came, didn't
there, a period in the development of science beginning in the late 19th century, when people
began to realize that these statements were not entirely true, that this wasn't just a
body of objective fact which had been read-off from the world. In other words, that
science was corrigible, scientific theories could be wrong. And that raises some very profound
questions. I mean, if science isn't just an objectively true description of the way
things are, what is it? And if we don't get it from observing the world, where do we get it from?
Well, I don't wanna say that we don't get it from observing the world at all. Obviously,
part of this Kantian image is that there IS a contribution which is not us, there's something
"out there". But that also there's a contribution from us. And even Kant, by the way, thought
that Newton science was indubitable. In fact, he thought we contributed its indubitability.
The step beyond Kant is the idea that not only is reality partly mind-dependent, but
that there are alternatives. And that the concepts we impose on the world may not be
the right ones and we may have to change them; that there's an interaction between what
we contribute and what we find out. But now, what was it that made people begin to realize that
this basic conception of science as objective truth was wrong? That science was corrigible,
that science was fallible? I think it's that the older science turned out to be wrong when
no one expected it to be wrong, not in detail but in the big picture. It's not that we find
out that, say, the Sun isn't 93 million miles from the Earth but only 20 million from the
Earth. That's not going to happen. I mean, sometimes it makes blunders even about
things like that, but that's like making a blunder about whether there's a chair in the room.
Wholesale skepticism about whether numerical values are right in science would be as
unjustified as wholesale skepticism about anything. But where the newer theories don't agree
with Newton is not over the approximate truth of the mathematical expressions in Newton's
theory -- those are still perfectly good for calculation -- it's over the big picture. We've replaced the
picture of an absolute space and an absolute time by the picture of a four-dimensional spacetime.
We've replaced the picture of a Euclidean world by a picture of a world which obeys a geometry
Euclid never dreamed of. We've swung back to the picture of the world as having a
beginning in time which is really a shocker. It's not even that things once refuted stay
refuted forever. So it means really that a whole conception of science has been superseded.
Instead of thinking of science as a body of knowledge which is being added to all the
time by further scientific work. That whole conception of science has been dispensed
with really, and we now think of it as a set of theories which are themselves constantly being
replaced by better theories, by more accurate theories, by richer, more explanatory theories.
And even the theories we now have like those of Einstein and his successors will
probably be replaced in the course of time by other better theories, by scientists yet
unknown, isn't that so? That's exactly right. In fact, scientists themselves make this prediction.
That is, that the main theories of the 20th century, relativity and quantum mechanics, will give
way to some other theory which will interpret both of them and so on forever. Now, this
raises a very fundamental question: namely, the question "What is truth?". I mean, when we
say that this or that scientific statement is true, or this or that scientific theory is true, what,
in these newly understood circumstances of ours, can we mean by "truth"? There are
still two views as there have been since Kant. One is this old correspondence view,
still has its adherents. But I think the view that's coming in more and more is that one
cannot make a total separation between what's true and what our standards of assertability are.
That the way in which the--what I called using the Kantian picture the "mind-dependence of
truth" comes in--is the fact that what's true and what's false is in part a function of
what our standards of truth and falsity are. And that depends on our interests, which
again change over time of course. That's right. I'd like you to say a little more about this question
of truth because, this again, I think is puzzling to the layman. I think that people who are
not trained in science or philosophy are apt to think there are a certain set of facts and a
true statement is a statement that accurately describes those facts. I'd like you to talk
a little about some of the difficulties that are actually involved in this. I think the
biggest difficulty in science itself comes from the fact that, even within one scientific
theory, you often find different accounts can be given of so-called facts. This came in
with the special theory of relativity when it turned out that facts about simultaneity,
whether two things happen at the same time, could be described differently by different
observers. One could say "boy-scout A fired his starter's pistol before boy-scout B", the other
could say "no, boy-scout B fired his starter's pistol before boy-scout A". And if the distance
is sufficiently large so that a light signal can't travel from one to the other without
exceeding the speed of light, then it may be both descriptions are correct, both are
admissible. Of course, this leads to profound conceptual difficulties in understanding some
modern scientific theories. This prompts the thought that a scientific theory can be useful
and meaningful, it can work, even if nobody really quite understands what it means. This
is the case with quantum mechanics, isn't it? I mean, nobody is really sure what quantum
mechanics actually means, and yet it works. That's right. And again, I wanna say one shouldn't
push that too far because I think we don't wanna give up our standards of intelligibility altogether.
We want to say quantum mechanics works and the very fact that it works means that there's
something fundamentally right about it. And with respect to its intelligibility, we're willing to
say, in part, that may be that we have the wrong standards of intelligibility, that we have
to change our intuitions. But in part, there are real paradoxes in the theory and I
think that more work has to be done to really get a satisfactory resolution of these paradoxes.
I think somebody hearing our discussion and to whom perhaps some of these ideas are new,
might find himself thinking, well, if all this is so, how is it that science works? If traditional
scientific theories are breaking down; if science is turning out not to be a body of
reliable, permanent, firm objective knowledge; if a significant proportion of every scientific
theory is subjective anyway in the sense that it's contributed by the human mind, by the observer,
by the scientist--how is it in these circumstances that we can actually build bridges, fly airplanes,
make rockets go to the moon, and actually make all this soft, fuzzy, changing, partly
subjective body of theory work for us? It must fit the world in some very basic way, in
spite of everything that we've been saying. That's true, but I think the contrast between being
subjective and fitting the world isn't altogether right. I'm not saying that scientific knowledge
is subjective or that "anything goes". I'm saying we're in the difficult position
that we often are in life of thinking there is a difference between good and bad
reasoning, but we don't have a mechanical rule. In everyday life, we use interest-loaded terms.
We wouldn't say that there's a policeman on the corner if we didn't have a whole network
of social institutions. Somebody coming from a primitive tribe which didn't have policemen
might say there's a man in blue on the corner. But the fact that the notion of a policeman
is shaped by our interests doesn't mean that it can't be objectively true that there's a
policeman on the corner. Also, I think science works precisely because of this corrigibility
in large part, as Professor Popper's pointed out. The difference between science and previous
ways of trying to find out truth is, in large part, that scientists are willing to test their ideas
because they don't regard them as infallible, in a way that was known at the beginning and then in
the success of Newton science somewhat forgotten. And we've had to be reminded again of what
Bacon knew, that you have to put questions to nature and be willing to change your
ideas if they don't work. In some respects, the traditional opposition between science and
religion has--the two parties have crossed places haven't they? I mean, many religious people
now believe they have certain knowledge about the world--that it was created by a God, that He
made us in His own image, gave us immortal souls which will survive our death, and so on--
certain very fundamental propositions which they hold with absolute certainty. And it's
the scientist who believes that everything is fallible, that the world is a mysterious
place, that we'll never get to the end of the mystery of, and so on. Isn't there
something in that? Maybe. I'm not sure... Well, let's not pursue that. But one point
I do want to take up with you, leaving even religion aside, is that, now that science is
seen in this entire different way that you've been describing, by virtually all scientists,
doesn't it mean that the difference between science and non-science isn't what it was
always thought of as being? In other words, since science is so subjective, indefinite,
changing, & so on, it's no longer a clearly-cut and different kind of human activity or kind of
human knowledge from other sorts of human knowledge and other sorts of human activity?
I think that's both true & culturally very important. I think the harm that the old picture
of science does is that if there is this realm of absolute fact that scientists are
gradually accumulating, then everything else appears somehow as non-knowledge, something
to which even words like 'true' and 'false' can't properly apply. I think that the so-called
fact-value dichotomy is a very good example of this. It's hard to have a discussion on
politics, for example, without someone very quickly saying, at least in my country, "Is
that a fact or a value judgment?", as though it can't be a fact that Hitler was a bad man,
for example, or a fact that Farrah Fawcett is a beautiful woman. And do you think that it
is a fact that Hitler was a bad man? Oh yes I do. [LAUGHTER] I do too! But then, if this is so, if
we are abandoning so many of these comfortable clear-cut distinctions of the past, what's
the point of continuing to use the category or the notion or the term 'science' anyway? I mean,
does it any longer clearly demarcate something differentiable from everything else? I don't
think it does. I think that if you're going to distinguish science from non-science, that
makes a lot of sense if you still have this old view that there's this inductive method
and what makes something science is that it uses it and uses it pretty consciously
and pretty deliberately, and that what makes something non-science is either it uses it
entirely unconsciously, as in learning how to cook, you're not consciously thinking about
inductive logic, or perhaps doesn't use it at all as metaphysics was alleged not to use
it at all, I think unfairly. But once you say, both say that there's a sharp line between,
say, practical knowledge & science, and to say that the method which is supposed to draw
this line is rather fuzzy, something that we can't state exactly. And attempts to state it,
by the way, have been very much a failure still. Inductive logic cannot be, say, programmed
on a computer the way deductive logic can be programed on a computer. I think the development
of deductive logic in the last hundred years and the development of the computer have
really brought home very dramatically just what a difference state we are in with respect to
"proof" in the mathematical sciences which we can state rigorous canons for, and "proof" in
what used to be called the "inductive sciences", where we can state general maxims but you
really have to use intuition, general know-how, and so on in applying them. One of the two
categories that you described the old-fashion way of looking at science in terms of was
that there was a particular scientific method; that you observe the facts and on the basis
of these observed instances, you generalized to form scientific theories which you then
verified by experiment. That was the old view. Now that that has been abandoned, is there
any longer any single method which is thought of as being scientific method? I don't think
there should be. People talk of scientific method as a sort of fiction, but I think that,
even in physics, where you do get experiments and tests which pretty much fit the textbooks
-- there's a great deal that does and then a great deal that shouldn't. And I think, in fact, in the
culture I don't really believe there's an agreement on what's a science & what isn't. Any university
will tell you in its catalogue there are things called "social sciences" and that sociology
is a science and that economics is a science. I bet if you ask anyone in the physics department
whether sociology is a science, he'll say "no". But why would he say "no"? That's interesting.
I think the real reason is not that the sociologist don't use the inductive method--they probably
use it more conscientiously, poor things, than the physicists do--I think it's because
they're not as successful. So in other words, science has become almost a name for successful
pursuit of knowledge. That's right. Yeah. Well now, I think you've given a very good description
of the way in which this age-old view of what science was has broken down in our century
and been replaced by something much more fluid and perhaps much more difficult to get hold of.
But you have, I think, described it very clearly. Can we now come against this background to
what philosophers of science are actually doing. You are a philosopher of science, what do
you and your colleagues do? Well, part of what we do, which I won't try to describe on
this broadcast, is fairly technical investigation of specific scientific theories. We look at
quantum mechanics very closely, both to learn what lessons we can from it for philosophy,
and to see what contributions we can make as philosophers to clarifying its foundations.
We look at relativity theory very closely, we look at Darwinian evolution very closely,
and so on. This is the part of philosophy of science that provides the data for the rest.
But much philosophy of science shades over into general philosophy. And I think the
best way to describe it is in terms of what we've been talking about. That is, each of
the issues we've been talking about divides philosophers of science. There are philosophers
of science who have a correspondence view of truth and try to show this came be made
precise, the objections can be overcome, you can still view science somehow in the old
way. And there are others who try to sketch what another view of truth would come to.
There are philosophers who still think there is an inductive method that can be
rigorously stated & who work on inductive logic. By the way, I think it's important there should
be, because we won't make progress trying to state the inductive method if there aren't. And
that there are others who view the development of science more culturally, more historically.
And then, people like myself, who have a sort of in between position; that there's
something to the notion of a scientific method, there are clear examples, but that it's more
or less a continuum, you mustn't think of it as a kind of mechanical rule, an algorithm
that you can apply to get scientific knowledge. So that I'd say each of these issues: the nature of
truth, the nature of the scientific method, whether there's any necessary truths in science, any
conceptual contribution which is permanent and can't be subject to revision is a big question.
And who are you, plural, doing all this work for? I don't ask that in an irreverent way,
but what I have in mind is this. I've myself taking part in attempts to bring scientists
and philosophers together for discussions of precisely the issues that you've raised,
and these attempts have usually failed and failed for the same reason: namely, that the
scientists lose interest. They go back to their laboratories and get on with doing more
science. And the great bulk of working scientists, it seems to me, don't in fact take very much of
an interest in the issues you've been talking about. I think it's conspicuous that the greatest of all
scientists are exceptions. The really blockbusting, the path-breaking scientists who've actually
made the revolution in this century that you've been talking about: people like Einstein, Max Planck,
Neils Bohr, Max born, Schrödinger, de Broglie... These people were enormously interested in the
conceptual questions that you've raised, but these were the pioneering geniuses, and the great mass of
thousands of scientists who follow on behind them and put their work to its practical application,
they don't seem to care. So, who is listening to you? Who is reading the stuff that you publish?
Well I'd say, first of all, I think we are basically writing for the philosophically interested
layman, for the reader of philosophy. I don't view philosophy of science as giving direct
advice to scientists, just as I think moral philosophers are ill-advised to think that
they're giving at least immediately current, contemporary advice on how to live your
life or what bills to pass in Parliament. On the other hand, I do think that scientists tend
to know the philosophy of science of 50 years ago. And perhaps this isn't a bad thing. That is,
perhaps this time lag, this culture lag has some value in weeding out what they shouldn't pay
attention to. I mean, it's annoying for a philosopher to encounter a scientist who's both sure that
he needn't listen to any philosophy of science and then who produces verbatim ideas which you
can recognize as coming from what was popular in 1928. Is there a direct parallel here between
what you're saying about scientists and Keynes, the economist Keynes' famous remark that
nearly all businessmen who thought that they were indifferent to airy-fairy economic theory,
were in fact the slaves of the economic theorists of yesterday and the previous generation?
That's exactly true. I suppose another parallel one could make would be to say that the account
that ordinary language users give of language and their use of language would be extremely
unsophisticated simply because they take it for granted and never thought about it. That too
would probably apply to the account that most scientists would give of what they
were doing when they were doing their science. That's right. That is, it's a mistake to think
that merely because one practices an activity, one can give a theory of it. One criticism that's
often been made about philosophers of science is that although they talk of "science" in
this general way, what they're nearly always referring to, in fact, is one science: namely,
physics. Now, it's true, isn't it, that the science in which the most exciting developments have
probably taken place in the last 20 years anyway has been not physics but biology. Are
philosophers of science genuinely open to the criticism of being too physics-based in their
view of science & having ignored biology too much? I think I would defend us against that
on the grounds that, although the theories in biology are of great scientific importance
--Darwin's theory of evolution, Crick-Watson on DNA, and so on--they don't, by and large,
pose big methodological problems of a kind that don't arise in physical science. I'm not
sure whether you're going to agree with that. Well, I mean, you mentioned the word
'evolution' just now & it seems to me that here is a concept which originated in one of the sciences,
namely, biology, and which over a comparatively short period of time has spread throughout
the whole of our culture. So that the way almost everybody thinks is influenced by the
notion of evolution, not only about the origins of man, but about institutions, or the arts,
or all kinds of other things. I mean, evolution has become a dimension of western man's thinking
about almost anything, is that not so? That's right. And perhaps there has not been enough
attention to this theory. Though what strikes me as interesting is that the possibility of explanations
of what we think of as the biological kind-- explanations in terms of function rather
than in terms of physics and chemistry, what you're made of--have come under more
attention recently as a result of computer science. Now, this does raise something I'm particularly
interested in when you talk of computer science & that is the interaction between our technology
in the case of computers and philosophy; not just science and philosophy, but technology
and philosophy. I mean, computers were originally constructed on the basis of a self-conscious
analogy with the human mind. But as they became more and more sophisticated, we began to
learn things from them about the human mind. So our construction of computers & what they
then tell us about ourselves seems to actually precede by interactive growth, isn't that so?
That's right. And today---this is one area, by the way, in which philosophers are in
close contact with scientists. That is, the fields of linguistics, cognitive psychology, computer
science, and philosophy of language today interact constantly, people send papers to one
another, not because someone tells them to, there are conferences in which specialists in these
fields meet together, again not because someone decided there should be some cross-fertilization.
The interesting thing about the computer case is one might've thought that the computer,
the rise of the computer, would encourage a certain kind of vulgar Materialism.
The idea: so after all, we are machines, so after all, everything about us can be
explained in terms of physics & chemistry. Paradoxically, the real effect of the computer on
psychology and on philosophy of mind has been a decrease in that kind of Reductionism.
See, the thing about the computer is that when you work with computers, you very rarely have
to think about their physics and chemistry. There's a distinction that people draw between their
"software", meaning their program, their instructions, their rules, the way they do things, & their "hardware".
And generally you ignore their hardware, you talk about computers at the software level, and
you wouldn't really be able to explain what they do in a way that would be of any use
to anyone in terms of the hardware level. There is a kind of emergence here, although
it's not a mystical kind of emergence, it's not that they're violating the laws of physics.
It's just that higher-level facts about organization have a kind of autonomy. The fact that it's
following this program explains why it does this and I don't need to know how it's built,
I only need to know it can be built in such a way that it will follow this program...
If you apply this to the mind, it suggests a return to a view of the mind that I associate
with Aristotle. It's the view that we are not "ghosts in a machine", not spirits which are
only temporarily in bodies, but that the relation between the mind & the body is a relation
of function to what has that function. Aristotle said that, if you use the word "soul"
in connection with an axe--of course he said you don't-- you'd say the soul of an axe is cutting.
And he said the soul of the eye is seeing, and he thought of man as a thing that thinks.
You're talking now of the alternative to Materialism and, say, a religious view that this gives
us, puts me in mind instantly of the most significant of all the Materialist philosophies
in the modern world: namely, Marxism, which after all, is the official state philosophy
of about a third of mankind as we sit here discussing this. Marxism claims to be scientific
and this is a very important thing about it. Is there a significant Marxist contribution
to the philosophy of science? I don't think there's a significant Marxist contribution,
but I don't think that the Marxists were all wrong either. I think Engels was one of the
most scientifically learned men of his century. He got a number of things wrong, but he
had an immense general scientific knowledge. And Anti-Dühring, his big book on philosophy of
science, although it contains some rather strange ideas, some of which he gets from Hegel by the way,
is, on the whole, a sensible book on philosophy of science, among other things. On the other
hand, it's not specifically Marxist. I'd say that Engels views in the philosophy of science
are in large part influenced by the standard philosophy of science of the time. They're
a fairly sophisticated inductive account. And what about subsequent Marxists thinkers
who also had some pretension to be philosophers, like Lenin, for example? Lenin, I think, is on the
whole, one of the worst. He says, for example, that theories are "copies" of motion. I mean, there
you have the copy theory; science is just copying off the reality in its crudest view. Mao is
more sophisticated. Mao was very influenced by John Dewey who was widely read in China
in the 1920s. Do you think it's actually made a contribution to the subject as it is
today or not really? I think that it anticipated --it perhaps might've made a contribution if
people had been less ideologically divided because I think non-Marxists could've learned--the
Marxists were among the first people to try to somehow combine a Realist view with a
stress on practice, with a stress on corrigibility. And they were very hostile to the notion of
a priori truth & today many mainline philosophers of science are very hostile to a priori truth.
As it is, they play somewhat the role in philosophy of science, I think, that Keynes said
they'd play in economics. He described Marx as one of his sort of underground predecessors. Yes, yes.
When I was introducing this program, I mentioned not only the philosophy of science, but also the
philosophy of mathematics. And before we close, I would like us to say something about that anyway.
I suppose one could really say that the central problem in the philosophy of mathematics
is a direct parallel to the central problem in the philosophy of science: namely, how does
it fit the world? With science, it's how does science fit the world? In mathematics, it's how
does mathematics fit the world? Is that right? That's right and it's even worse, because if you're
trying to defend a "copy view", a correspondence view of truth in empirical science, you can
answer the question "well how do we build-up this picture in such a way that corresponds?" by
saying that we have sense organs. As I mentioned before that's not a total answer because
there's a tremendous amount of interpretation involved in simple seeing & simple hearing.
But if you're talking about numbers and sets, and someone says okay if mathematical knowledge
is simply some kind of a copy of the way numbers ARE and the way sets are, and the way other
abstract objects that mathematicians study are, the question [is] then: what SENSE enables us
to see how they are? What is a number? Yes, yes. A deeply problematic question but still an
important one. On the other hand, I don't want to say that the anti-correspondence
view has it very easy either. It seems to me that mathematical knowledge is a real puzzle. And
I think that philosophers should concentrate more on philosophy of mathematics than they
do now because it seems to be an area where no theory works very well. Isn't there another
very important parallel between mathematics and science? I mean, throughout the history of
science, one of the conflicts has been between one camp who thought that it was all about
objects in the world which existed independently of human experience, and another camp which
thought no it's human beings and observers who actually contribute most of this.
And as you pointed out much earlier in our discussion, the truth is almost certainly a
combination of both. There is a long standing dispute in mathematics between one body of
people who think that mathematical knowledge is something that's, sort of speak,
inherent in the structure of the world, and we derive it from the world by experience
& observation, and another body of mathematical thought that says no, mathematics is a creation
of the human mind which we then try to impose on reality like a grid, as it were, on a landscape.
Isn't that so? That's right. The latter story is attractive because of the sense organ problem,
but it doesn't seem to work either because it seems that we're not free to impose any mathematics
or any logic we want. Almost anyone would admit that at least you have to be consistent
and what's consistent and what isn't, isn't somehow something we can just make-up or
decide. When we try to stress conventionalist accounts, subjective accounts, we come up
against the objectivity of mathematics. When we try to stress the objectivity of mathematics
we come up against another set of problems. I think we can learn a lot more than we now
know about human knowledge & about scientific knowledge by going further into this area.
Talking of where we're going from where we are, sort of speak, I think the most interesting way
in which you could end this discussion Professor Putnam would by talking about what you
regard as the most interesting problems areas at the moment, and therefore, I take it, the most
likely growth areas for the immediate future in both of the subjects we've been discussing:
philosophy of science & philosophy of mathematics. Okay, I think that--if I'm allowed to confine
my prediction to the immediate future, because we know that long-run predictions are
always false. But in the immediate future, I would expect philosophy of mathematics to be a
growth area & philosophy of logic. I would expect philosophy of physics, I think, to decline
somewhat from its central place in philosophy of science. Although I think, part of it
touches philosophy of logic. The astounding suggestion has actually come forward,
in connection with quantum mechanics, that we may have to change our logic,
our view of what the true logical laws are, in order to really understand how the world can be
quantum mechanical. I think this side of philosophy of quantum mechanics that touches philosophy
of logic will be a hot discussion area. But more generally, I think, areas which we almost
don't think of as philosophy of science that become philosophy of language and philosophy
of mind, like these questions about computer models of the mind, computer models of language,
and these more general questions about theories of truth, the nature of truth, the nature of
verification, how science can be objective even though there's not a rigorous scientific
method. I think these questions will continue to be the staples of the field. One thing
that worries me about this whole area is its relationship to the educated layman, I mean, which
in a sense is the person our discussion has been for. After all, it's now over 70 years since
the 25 year old Einstein published the theory of relativity, and I'm sure you agree with
me that it's true to say now that the great majority of educated people with higher educations,
university degrees, and so on, still have scarcely any idea of what this is all
about. And it's done very little to actually influence their view of the world. Isn't there
a danger that now science and mathematics are simply racing ahead and the whole new
range or world of insight that that is giving us into the universe in which we live simply
isn't filtering through to the non-specialist, or not filtering through anything fast enough?
That is a danger, but it's one that something can be done about. There's now, for example, a
text of special relativity called "Spacetime Physics" which is designed for the first month of
the first Freshman college physics course. And the authors say at the beginning that
they look forward to the time when it will be taught in high schools. And do you think
that time will in fact come? Oh I'm sure of it. Yes. Well, I think you're right and indeed I hope you are.
Thank you very much Professor Putnam. Thank you.
Putnam is one of my favorite philosophers. It makes me very sad that we lost him this year.
I love that this show was on mainstream television. Their attempts in those days to dumb-down philosophy and science were nowhere near as patronising as the attempts these days in science docutainments.