What Is Realism.pdf

What Is "Realism"?

Author(s): Hilary Putnam

Source: Proceedings of the Aristotelian Society, New Series, Vol. 76 (1975 - 1976), pp. 177-194

Published by: Blackwell Publishing on behalf of The Aristotelian Society

Stable URL: http://www.jstor.org/stable/4544887

Accessed: 26/10/2008 10:31

Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at

http://www.jstor.org/page/info/about/policies/terms.jsp . JSTOR's Terms and Conditions of Use provides, in part, that unless

you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you

may use content in the JSTOR archive only for your personal, non-commercial use.

Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at

http://www.jstor.org/action/showPublisher?publisherCode=aristotelian .

Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed

page of such transmission.

JSTOR is a not-for-profit organization founded in 1995 to build trusted digital archives for scholarship. We work with the

scholarly community to preserve their work and the materials they rely upon, and to build a common research platform that

promotes the discovery and use of these resources. For more information about JSTOR, please contact support@jstor.org.

The Aristotelian Society and Blackwell Publishing are collaborating with JSTOR to digitize, preserve and

extend access to Proceedings of the Aristotelian Society.

http://www.jstor.org

X*-WHAT IS "REALISM"?

by Hilary Putnam

While it is undoubtedly a good thing that "ism" words have

gone out of fashion in philosophy, some "ism" words seem

remarkably resistant to being banned. One such word is

"realism". More and more philosophers are talking about

realism these days; but very little is said about what realism

is. This paper will not answer that very large question; but

I hope to contribute a portion of an answer.

Whatever else realists say, they typically say that they

believe in a Correspondence Theory of Truth.

When they argue for their position, realists typically argue

against some version of Idealism-in our time, this would be

Positivism or Operationalism. (This is not in itself surprising

-all philosophers attempt to shift the burden of proof to

their opponents. And if one's opponent has the burden of

proof, to dispose of his arguments seems a sufficient defence

of one's own position.) And the typical realist argument

against Idealism is that it makes the success of science a

miracle. Berkeley needed God just to account for the success

of beliefs about tables and chairs (and trees in the Quad);

but the appeal to God has gone out of fashion in philosophy,

and, in any case, Berkeley's use of God is very odd from the

point of view of most theists. And the modern positivist has

to leave it without explanation (the realist charges) that

''electron calculi' and "space-time calculi" and "DNA

calculi" correctly predict observable phenomena if, in reality,

there are no electrons, no curved space-time, and no DNA

molecules. If there are such things, then a natural explana-

tion of the success of these theories is that they are partially

true accounts of how they behave. And a natural account of

the way in which scientific theories succeed each other-say,

the way in which Einstein's Relativity succeeded Newton's

Universal Gravitation-is that a partially correct/partially

* Meeting of the Aristotelian Society at 5/7, Tavistock Place, London,

W.C.i, on Monday, 23rd February 1976, at 7.30 p.m.

178

HILARY PUTNAM

incorrect account of a theoretical object-say, the gravita-

tional field, or the metric structure of space-time, or both-

is replaced by a better account of the same object or objects.

But if these objects don't really exist at all, then it is a miracle

that a theory which speaksof gravitational action at a distance

successfully predicts phenomena; it is a miracle that a theory

which speaks of curved space-time successfully predicts

phenomena; and the fact that the laws of the former theory

are derivable "in the limit" from the laws of the latter theory

has no explained methodological significance.

I am not claiming that the positivist (or whatever) has no

rejoinder to make to this sort of argument. He has a number:

reductionist theories of the meaning of theoretical terms,

theories of explanation, etc. Right now, my interest is rather

in the following fact: the realist's argument turns on the

success of science, or, in an earlier day, the successof common

sense material object theory. But what does the success of

science have to do with the Correspondence Theory of

Truth?-or any theory of truth, for that matter?

That science succeeds in making many true predictions,

devising better ways of controlling nature, etc., is an un-

doubted empirical fact. If realism is an explanation of this

fact, realism must itself be an over-arching scientific

hypothesis. And realists have often embraced this idea, and

proclaimed that realism is an empirical hypothesis. But then

it is left obscure what realism has to do with theory of truth.

In the present paper, I shall try to bring out what the con-

nexion between these two concerns of the realist is-what

the connexion is between explaining the successof knowledge

and the theory of truth.

1. The "convergence"of scientific knowledge

What I am calling "realism" is often called "scientific

realism" by its proponents. If I avoid that term here, it is

because "scientific realist", as a label, carries a certain

ideological tone-a tone faintly reminiscent of igth century

materialism, or, to be blunt about it, village atheism. Indeed,

if a "scientific realist" is one who believes, inter alia, that all

knowledge worthy of the name is part of "science", then I am

not a "scientific realist". But scientific knowledge is certainly

an impressive part of our knowledge, and its nature and

WHAT IS "REALISM"?

179

significance have concerned all the great philosophers

interested in epistemology at all. So it is not surprising that

both realists and idealists should claim to be "philosophersof

science", in two senses of "of". And if I focus on scientific

knowvledgein what follows, it is because the discussion has

focused on it, and not out of a personal commitment to

scientism.

To begin with, let me say that I think there is something

to the idea of convergence in scientific knowledge. What there

is is best explained, in my opinion, in an unpublished essay

by Richard Boyd.' Boyd points out that all that follows from

standard (positivist) philosophy of science is that later theories

in a science, if they are to be better than the theories they

succeed, must imply many of the observation sentences of the

earlier theories (especially the true observation sentences

implied by the earlier theories). It does not follow that the

later theories must imply the approximate truth of the

theoretical laws of the earlier theories in certain circum-

stances-which they typically do. In fact, preserving the

mechanisms of the earlier theory as often as possible, which is

what scientists try to do (or to show that they are "limiting

cases" of new mechanisms)-is often the hardest way to get

a theory wvhichkeeps the old observational predictions, where

they were correct, and simultaneously incorporates the new

observational data. That scientists try to do this-e.g.,

preserve conservation of energy, if they can, rather than postu-

late violations-is a fact, and that this strategy has led to

important discoveries (from the discovery of Neptune to the

discovery of the positron) is also a fact.

Boyd tries to spell out Realism as an empirical hypothesis

by means of two principles:

(i) Terms in a mature science typically refer.

(2) The laws of a theory belonging to a mature science are

typically approximately true.

What he attempts to show in his essay is that scientists act

as they do because they believe (1) and (2) and that their

strategy works because (i) and (2) are true.

One of the most interesting things about this argument is

that, if it is correct, the notions of "truth" and "reference"

have a causal-explanatory role in epistemology. (i) and (2)

18o

HILARY PUTNAM

are premisses in an explanation of the behaviour of scientists

and the success of science-and they essentially contain con-

cepts from referential semantics. Replacing "true",in premiss

(2) (of course, Boyd's argument needs many more premisses

than just (i) and (2)) by some Operationalist "substitute"-

e.g., "is simple and leads to true predictions"-will not

preserve the explanation.

Let us pause to see why. Suppose T1 is the received theory

in some central branch of physics (physics surely counts as a

"mature" science if any science does), and I am a scientist

trying to find a theory T2 to replace T1. (Perhaps I even know

of areas in which T1 leads to false predictions.) If I believe

principles (i) and (2), then I know that the laws of T1 are

(probably) approximately true. So T2 must have a certain

property-the property that the laws of T1 are "approxi-

mately true" when we judge from the standpoint of T2-or

T2 will (probably) have no chance of being true. Since I want

theories that are not just "approximately true", but theories

that have a chance of being true, I will only consider theories,

as candidates for being T2,which have this property-theories

which contain the laws of T1 as a limiting case. But this is

just the feature of the scientific method we discussed. (Boyd

also discusses a great many other features of the scientific

method-not just this aspect of "convergence"; but I do

not need to go into these other features here.) In fine, my

knowledge of the truth of (1) and (2) enables me to restrict

the class of candidate-theories I have to consider, and thereby

increases my chance of success.

Now, if all I know is that T1 leads to (mainly) true predic-

tions in some observational vocabulary (a notion I have

criticized elsewhere2), then all I know about T2 is that it

should imply most of the "observation sentences" implied by

T1. But it does not follow that it must imply the truth of

the laws of T1 in some limit. There are many other ways of

constructing T2 so that it will imply the truth of most of the

observation sentences of T1; and making T2 imply the

"approximate truth" of the laws of T1 is often the hardest

way. Nor is there any reason why T2should have the property

that we can assign referents to the terms of T1from the stand-

point of T2. Yet it is a fact that we can assign a referent to

"gravitational field" in Newtonian theory from the stand-

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika: