Evolutionary Epistemology and the Aim of Science

Abstract

Both Popper and van Fraassen have used evolutionary analogies to defend their views on the aim of science, although these are diametrically opposed. By employing Price's equation in an illustrative capacity, this paper considers which view is better supported. It shows that even if our observations and experimental results are reliable, an evolutionary analogy fails to demonstrate why conjecture and refutation should result in: (1) the isolation of true theories; (2) successive generations of theories of increasing truth-likeness; (3) empirically adequate theories; or (4) successive generations of theories of increasing proximity to empirical adequacy. Furthermore, it illustrates that appeals to induction do not appear to help. It concludes that an evolutionary analogy is only sufficient to defend the notion that the aim of science is to isolate a particular class of false theories, namely those that are empirically inadequate.

Notes

²Compare Popper 1959: 42]: ‘[W]hat characterizes the empirical method is its manner of exposing to falsification, in every conceivable way, the system to be tested. Its aim is not to save the lives of untenable systems but, on the contrary, to select the one which is by comparison the fittest, by exposing them all to the fiercest struggle for survival.’

¹This should not be confused with an alternative programme which may be described similarly, the so-called EEM (Evolution of Epistemological Mechanisms) programme, which involves ‘extension of the biological theory of evolution to those aspects or traits of animals which are the biological substrates of cognitive activity’[Bradie 1990: 245–6].

³Whereas Popper uses the evolutionary analogy in a sustained attempt to establish his view on the aim of science, van Fraassen only mentions it briefly. But we shall see that it fails the latter even in an illustrative capacity.

⁴It may also be the case that performing some functions is more glamorous than performing others. Just as a talented goal scorer will attract more praise than a skilled defender, so a great theoretician might be more lauded than a brilliant experimentalist.

⁵It should be noted that this definition requires interpretation in order for the analogy with competitive games, like chess and football, to hold. In these cases, the probability is high that one opponent or the other will succeed in achieving the aim of the game (although the situation is complicated somewhat by the possibility of draws).

⁶My thanks to an anonymous referee for this example.

⁷More carefully, we need only allow that there is at least one way to do science—one method—such that it reliably makes continual progress towards x.

⁸For a fuller treatment, see Okasha 2006: §1.2].

⁹See Okasha 2006: 22] for a full derivation.

¹⁰Bradie 1986, 1990, for instance, writes of the EET (Evolution of Epistemic Theories) programme.

¹¹We shall not consider Bird's 2007 recent proposal that scientific progress is best understood in terms of knowledge. This is not only due to the reservations of Rowbottom 2008b, but also because knowledge requires truth.

¹²This absence of cumulativity in this case may lead some to think that the analogy with evolution is inappropriate. I am not so sure. Imagine a small population of beings that reproduce, and have offspring that never manage to reproduce because they are all wiped out by a terrible virus before reaching sexual maturity. Clearly there may have been selection from the point of view of Price's equation. Some of the small initial population may have been killed by predators because of unfavourable traits. In that event, fewer of the offspring may possess those traits than they would have in the absence of the predators.

¹³It is unclear, in any event, why the entities in P must not be of different types provided that they each share the relevant attribute (and can appropriately ‘reproduce’).

¹⁴According to the result of Miller 1974, for instance, the number of true members would be equal to the number of false members.

¹⁵Reliability of basic statements is not sufficient, on such a probabilistic view, to ensure that such progress will occur. Analogously, it is possible to have a large number of ‘heads’ results in a row, on flipping an unbiased coin.

¹⁶Compare this earlier passage, which may appear to be in conflict: ‘Experiences can motivate a decision … but a basic statement cannot be justified by them—no more than by thumping the table’[Popper 1959: 105]. For further discussion, see Musgrave 2009.

¹⁷See Rowbottom 2008a, 2010 for more on this example, and also on Pauli's posit of the neutrino.

¹⁸As argued in Rowbottom 2008c, Objective Bayesianism in fact appears to be rather close, in key respects, to the logical interpretation of Keynes 1921.

¹⁹See the discussions of voluntarism in Charkravartty 2004 and Rowbottom 2010: ch. 1].

²⁰Just a little later, interestingly, Popper 1981: 83] advocated yet another, distinct, understanding of progress, saying that ‘the tentative adoption of a new conjecture or theory may solve one or two problems, but it invariably opens up many new problems; for a new revolutionary theory functions exactly like a new and powerful sense organ. If the progress is significant then the new problems will differ from the old problems: the new problems will be on a radically different level of depth. This happened, for example, in relativity … in quantum mechanics … in molecular biology … This, I suggest, is the way in which science progresses.’ We will not consider this here, but note that measurement of ‘depth’ is highly problematic.

²¹There are some rather obvious problems with van Fraassen's definition, e.g. ‘All tables are composed of atoms’ is a hypothesis concerning observables which might be empirically adequate, in the sense he intends, even if it is false. For present purposes, we shall assume that such difficulties can be dealt with.

²²See also the objection of Dicken 2007, which does not affect the argument here. Modal realism is not presupposed.

²³Admittedly this may also be the case for theories that are apparently empirically inadequate, owing to Duhem's thesis. But claims concerning empirical adequacy encounter the special difficulty discussed below whereas claims concerning empirical inadequacy do not. Furthermore, even if we accept Duhem's thesis we may nevertheless think that the aim of science is to rule out false theoretical systems. For more on Duhem's thesis and falsificationism, see Rowbottom [forthcoming].

²⁴This might even count as a minor victory for van Fraassen, given his epistemological voluntarism. There is, at least, no reason to favour the view that the aim of science is truth over the view that the aim of science is empirical adequacy.

²⁵I should like to thank Alexander Bird, Bence Nanay, Tim Williamson, and three anonymous referees for the Australasian Journal of Philosophy for their comments on, and criticisms of, previous versions of this paper. I should also like to thank the Templeton Foundation and the British Academy for funding this research.