Philosophy of Science

OUP CORRECTED PROOF – FINAL, 22/04/16, SPi OUP CORRECTED PROOF – FINAL, 22/04/16, SPi respects similar to a computer, and that human mental processes So part of the job of philosophy of science is to question can be unde...

OUP CORRECTED PROOF – FINAL, 22/04/16, SPi OUP CORRECTED PROOF – FINAL, 22/04/16, SPi respects similar to a computer, and that human mental processes So part of the job of philosophy of science is to question can be understood by comparing them to the operations assumptions that scientists take for granted. But it would be computers carry out. By contrast, the field of neuroscience studies wrong to imply that scientists never discuss philosophical issues how the brain itself works. Thanks to technological advances in themselves. Indeed historically, scientists have played a key role in brain scanning, neuroscientists are beginning to understand the the development of philosophy of science. Descartes, Newton, and underlying neural basis of human (and animal) cognition. This Einstein are prominent examples. Each was deeply interested in enterprise is of great intrinsic interest and may also lead to questions about how science should proceed, what methods of improved treatments for mental disorders. enquiry it should use, and whether there are limits to scientific knowledge. These questions still lie at the heart of contemporary The social sciences, such as economics, anthropology, and philosophy of science. So the issues that concern philosophers sociology, also flourished in the 20th century, though some believe of science have engaged the attention of some of the greatest they lag behind the natural sciences in terms of sophistication and scientists. That being said, it must be admitted that many predictive power. This raises an interesting methodological scientists today take little interest in philosophy of science, and question. Should social scientists try to use the same methods as know little about it. While this is unfortunate, it is not an natural scientists, or does their subject matter call for a different indication that philosophical issues are no longer relevant. approach? We return to this issue in Chapter 7. Rather it is a consequence of the increasingly specialized nature Philosophy of Science What is science? of science, and of the polarization between the sciences and the humanities that characterizes much modern education. What is philosophy of science? The principal task of philosophy of science is to analyse the You may still be wondering exactly what philosophy of science is methods of enquiry used in the sciences. You may wonder why all about. For to say that it ‘studies the methods of science’ is not this task should fall to philosophers, rather than to the scientists really to say very much. Rather than try to provide a more themselves. This is a good question. Part of the answer is that informative definition, we will instead examine a classic issue in philosophical reflection can uncover assumptions that are implicit the philosophy of science. in scientific enquiry. To illustrate, consider experimental practice. Suppose a scientist does an experiment and gets a particular result. Science and pseudo-science They repeat the experiment a few times and keep getting the same result. After that they will probably stop, confident that were the Recall the question with which we began: what is science? Karl experiment repeated again under exactly the same conditions, the Popper, an influential 20th-century philosopher of science, same result would obtain. This assumption may seem obvious, but thought that the fundamental feature of a scientific theory is that as philosophers we want to question it. Why assume that future it should be falsifiable. To call a theory falsifiable is not to say that repetitions of the experiment will yield the same result? How do it is false. Rather, it means that the theory makes some definite we know this is true? The scientist is unlikely to spend much time predictions which are capable of being tested against experience. puzzling over this: they probably have better things to do. It is a If these predictions turn out to be wrong, then the theory has been quintessentially philosophical question. falsified, or disproved. So a falsifiable theory is one which we 10 11  OUP CORRECTED PROOF – FINAL, 22/04/16, SPi OUP CORRECTED PROOF – FINAL, 22/04/16, SPi might discover to be false—it is not compatible with every possible and Marx’s theories, Einstein’s theory made a very definite course of experience. Popper thought that some supposedly prediction: that light rays from distant stars would be deflected by scientific theories did not satisfy this condition and thus did not the gravitational field of the sun. Normally this effect would be deserve to be called science at all; they were merely pseudo-science. impossible to observe—except during a solar eclipse. In 1919 the English astrophysicist Sir Arthur Eddington organized two Freud’s psychoanalytic theory was one of Popper’s favourite expeditions to observe the solar eclipse of that year, one to Brazil examples of pseudo-science. According to Popper, Freud’s theory and one to the island of Principe off the Atlantic coast of Africa, could be reconciled with any empirical findings whatsoever. with the aim of testing Einstein’s prediction. The expeditions Whatever a patient’s behaviour, Freudians could find an found that starlight was indeed deflected by the sun, by almost explanation of it in terms of their theory—they would never admit exactly the amount Einstein had predicted. Popper was very that their theory was wrong. Popper illustrated his point with the impressed by this. Einstein’s theory had made a definite, precise following example. Imagine a man who pushes a child into a river prediction, which was confirmed by observations. Had it turned with the intention of murdering him, and another man who out that starlight was not deflected by the sun, this would have sacrifices his life in order to save the child. Freudians can explain shown that Einstein was wrong. So Einstein’s theory satisfies the both men’s behaviour with equal ease: the first was repressed, and criterion of falsifiability. the second had achieved sublimation. Popper argued that through Philosophy of Science What is science? the use of such concepts as repression, sublimation, and Popper’s attempt to demarcate science from pseudo-science is unconscious desires, Freud’s theory could be rendered compatible intuitively quite plausible. There is surely something suspicious with any clinical data whatever; it was thus unfalsifiable. about a theory that can be made to fit any empirical data whatsoever. But many philosophers regard Popper’s criterion as The same was true of Marx’s theory of history, Popper maintained. overly simplistic. Popper criticized Freudians and Marxists for Marx claimed that in industrialized societies around the world, explaining away any data which appeared to conflict with their capitalism would give way to socialism and ultimately to theories, rather than accepting that the theories had been refuted. communism. But when this didn’t happen, instead of admitting This certainly looks like a dubious procedure. However there is that Marx’s theory was wrong, Marxists would invent an ad hoc some evidence that this very procedure is routinely used by explanation for why what had happened was actually perfectly ‘respectable’ scientists—whom Popper would not want to accuse of consistent with their theory. For example, they might say that the engaging in pseudo-science—and has led to important scientific inevitable progress to communism had been temporarily slowed discoveries. by the rise of the welfare state, which ‘softened’ the proletariat and weakened their revolutionary zeal. In this way, Marx’s theory Another astronomical example can illustrate this. Newton’s could be made compatible with any possible course of events, just gravitational theory, which we encountered earlier, made like Freud’s. Therefore neither theory qualifies as genuinely predictions about the paths the planets should follow as they orbit scientific, according to Popper’s criterion. the sun. For the most part these predictions were borne out by observation. However, the observed orbit of Uranus consistently Popper contrasted Freud’s and Marx’s theories with Einstein’s differed from what Newton’s theory predicted. This puzzle was theory of gravitation, known as general relativity. Unlike Freud’s solved in 1846 by two scientists, Adams in England and Leverrier 12 13  OUP CORRECTED PROOF – FINAL, 22/04/16, SPi OUP CORRECTED PROOF – FINAL, 22/04/16, SPi in France, working independently. They suggested that there was made if scientists simply abandoned their theories at the first sign another planet, as yet undiscovered, exerting an additional of trouble. gravitational force on Uranus. Adams and Leverrier were able to calculate the mass and position that this planet would have to The failure of Popper’s demarcation criterion throws up an have if its gravitational pull was indeed responsible for Uranus’ important question. Is it actually possible to find some common strange behaviour. Shortly afterwards the planet Neptune was feature shared by all and only the things we call ‘science’? Popper discovered, almost exactly where Adams and Leverrier predicted. assumed that the answer was yes. He felt that Freud’s and Marx’s theories were clearly unscientific, so there must be some feature Now clearly we should not criticize Adams’s and Leverrier’s which they lack and which genuine scientific theories possess. But behaviour as ‘unscientific’—after all, it led to the discovery of a whether or not we accept Popper’s negative assessment of Freud new planet. But they did precisely what Popper criticized the and Marx, his assumption that science has an ‘essential nature’ Marxists for doing. They began with a theory—Newton’s theory of is questionable. After all, science is a heterogeneous activity, gravity—which made an incorrect prediction about Uranus’ orbit. encompassing a wide range of disciplines and theories. It may be Rather than concluding that Newton’s theory must be wrong, they that they share some fixed set of features which define what it is to stuck by the theory and attempted to explain away the conflicting be a science, but it may not. The philosopher Ludwig Wittgenstein observations by postulating a new planet. Similarly, when argued that there is no fixed set of features that define what it is Philosophy of Science What is science? capitalism showed no signs of giving way to communism, Marxists to be a ‘game’. Rather there is a loose cluster of features most of did not conclude that Marx’s theory must be wrong, but stuck by which are possessed by most games. But any particular game may the theory and tried to explain away the conflicting observations lack any of the features in the cluster and still be a game. The in other ways. So surely it is unfair to accuse Marxists of engaging same may be true of science. If so, a simple criterion for demarcating in pseudo-science if we allow that what Adams and Leverrier did science from pseudo-science is unlikely to be found. counted as good, indeed exemplary, science? This suggests that Popper’s attempt to demarcate science from pseudo-science cannot be quite right, despite its initial plausibility. For the Adams/Leverrier example is by no means atypical. In general, scientists do not just abandon their theories whenever they conflict with the observational data. Usually they look for ways of eliminating the conflict without having to give up their theory; see Chapter 5. Also, it is worth remembering that virtually every scientific theory conflicts with some observations—finding a theory that fits all the data perfectly is extremely difficult. Obviously if a theory persistently conflicts with more and more data, and no plausible way of explaining away the conflict is found, it will eventually have to be rejected. But little progress would be 14 15