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[ Pobierz całość w formacie PDF ] of the he phenomena whose laws we may determine with precision. This is not to say that Comte was ignorant of science. He was trained by the great French theoretical physicists and applied mathematicians. I le believed in their laws of phenomena and distrusted any drive towards postulating new entities. Logical positivism had no such simplistic opportunities. ((50)) Members of the Vienna Circle believed the physics of their day: some had made contributions to it. Atomism and electromagnetism had long been established, relativity was a proven success and the quantum theories were advancing by leaps and bounds. Hence arose, in the extreme version of logical positivism, a doctrine of reductionism. It was proposed that in principle there are logical and linguistic transformations in the sentences of theories that will re-duce them to sentences about phenomena. Perhaps when we speak of atoms and currents and electric charges we are not to be under-stood quite literally, for the sentences we use are reducible to sentences about phenomena. Logicians did to some extent oblige. F.P. Ramsey showed how to leave out the names of theoretical entities in the theories, using instead a system of quantifiers. William Craig proved that for any axiomatizable theory involving both observational and theoretical terms, there exists an axiomatizable theory involving only the observational terms. But these results did not do quite what logical positivism wanted, nor was there any linguistic reduction for any genuine science. This was in terrible contrast to the remarkable partial successes by which more superficial scientific theories have been reduced to deeper ones, for example, the ways in which analytic chemistry is founded upon quantum chemistry, or the theory of the gene has been transformed into molecular biology. Attempts at scientific reduction reducing one empirical theory to a deeper one have scored innumerable partial successes, but attempts at linguistic reduction have got nowhere. Accepting Hume and Comte took all that stuff about fundamental particles and said: We don't believe it. Logical positivism believed it, but said in a sense that it must not be taken literally; our theories are really talking about phenomena. Neither option is open to a present-day positivist, for the programmes of linguistic reduction failed, while on the other hand one can hardly reject the whole body of modern theoretical science. Yet van Fraassen finds a way through this impasse by distinguishing belief from acceptance. Against the logical positivists, van Fraassen says that theories are to be taken literally. There is no other way to take them! Against the realist he says that we need not believe theories to be true. He invites us instead to use two further concepts: acceptance and empirical ((51)) adequacy. He defines scientific realism as the philosophy that maintains that, `Science aims to give us, in its theories, a literally true story of what the world is like; and acceptance of a scientific theory involves the belief that it is true' (p. 8). His own constructive empiricism asserts instead that, `Science aims to give us theories w which are empirically adequate; and acceptance of a theory involves as belief only that it is empirically adequate' (p. 12). "There is,' he writes, `no need to believe good theories to be true, nor to believe ipso facto that the entities they postulate are real.' The ' ipso facto' reminds us that van Fraassen does not much distinguish realism about theories from realism about entities. I say that one could believe entities to be real, not `in virtue of the fact' that one believes some theory to be true, but for other reasons. A little later van Fraassen explains as follows: `to accept a theory is (for us) to believe that it is empirically adequate that what the theory says about what is observable (by us) is true' (p. 18). Theories are intellectual instruments for prediction, control, research and sheer enjoyment. Acceptance means commitment, among other things. To accept a theory in your field of research is to be committed to developing the programme of inquiry that it suggests. You may even accept that it provides explanations. But you must reject what has been called inference to the best explanation: to accept a theory because it makes something plain is not thereby to kink that what the theory says is literally true. Van Fraassen's is the most coherent present-day positivism. It has all six features by which I define positivism, and which are shared by Hume, Comte and the logical positivists. Naturally it lacks Hume's psychology, Comte's historicism, and logical positivism's theories of meaning, for those have nothing essential to to with the positivist spirit. Van Fraassen shares with his predecessors the anti- metaphysics: `The assertion of empirical adequacy is a great deal weaker than the assertion of truth, and the restraint to acceptance delivers us from metaphysics' (p. 69). He is pro-observation, and anti- cause. He downplays explanation; he does not think explanation leads to truth. Indeed, just like Hume and :unte, he cites the classic case of Newton's inability to explain gravity as proof that science is not essentially a matter of explalint ion (p. 94). Certainly he is anti-theoretical-entities. So he holds live of our six positivist doctrines. The only one left is the emphasis ((52)) on verification or some variant. Van Fraassen does not subscribe to the logical positivist verifiability theory of meaning. Nor did Comte. Nor, I think, did Hume, although Hume did have an unverifiability maxim for burning books. The positivist enthusiasm for verifiability was only temporarily connected with meaning, in the days of logical positivism. More generally it represents a desire for positive science, for knowledge that can be settled as true, and whose facts are determined with precision. Van Fraassen's constructive empiricism shares this enthusiasm. Anti-explanation [ Pobierz całość w formacie PDF ] |