Michael Ruse

What are biological species? Aristotelians and Lockeans agree that they are natural kinds; but, evolutionary theory shows that neither traditional philosophical approach is truly adequate. Recently, Michael Ghiselin and David Hull have argued that species are individuals. This claim is shown to be against the spirit of much modern biology. It is concluded that species are natural kinds of a sort, and that any 'objectivity' they possess comes from their being at the focus of a consilience of inductions.

A common complaint of biologists is that their subject receives poor treatment from philosophers—it gets but a fraction of the attention accorded to physics and chemistry, and what little it does receive, is usually of the type where ‘All swans are white’ is taken to be a paradigmatic example of the state of biological thinking. It cannot be denied that this complaint is, to a great extent, justified; however, there are some notable breaches in the wall of ignorance and silence, amongst which must be numbered The Ascent of Life by T.A. Goudge. In this book, starting from what is obviously a very wide knowledge of biology, Goudge attempts a careful and thorough analysis of one of the major achievements of biological thought, evolutionary theory. The conclusions that Goudge draws are many; nevertheless, one can discern running through them a common theme, namely that whilst evolutionary theory is indeed a legitimate branch of science, to assume that it is a science of the same nature as physics and chemistry would be a grave error. Goudge argues that, despite certain similarities to other branches of science, the essential aims, methods and results of evolutionary theory are peculiar unto itself.

In recent years Sir Karl Popper has been turning his attention more and more towards philosophical problems arising from biology, particularly evolutionary biology. Popper suggests that perhaps neo-Darwinian evolutionary theory is better categorized as a metaphysical research program than as a scientific theory. In this paper it is argued that Popper can draw his conclusions only because he is abysmally ignorant of the current status of biological thought and that Popper's criticisms of biology are without force and his suggestions for its improvement are without need. Also it is suggested that Popper's desire to see scientific theory growth as being in some sense evolutionary may have led him astray about biology. And conversely it is suggested that since his claims about biology are not well taken his analysis of theory growth may well bear reexamination.

Two of the most influential evaluations of Charles Lyell's geological ideas were those of the philosophers of science, John F. W. Herschel and William Whewell. In this paper I shall argue that the great difference between these evaluations—whereas Herschel was fundamentally sympathetic to Lyell's geologizing, Whewell was fundamentally opposed—is a function of the fact that Herschel was an empiricist and Whewell a rationalist. For convenience, I shall structure the discussion around the three key elements in Lyell's approach to geology. First, he was anactualist: he wanted to explain past geological phenomena in terms of causes of the kind that are operating at present. Second, he was auniformitarian: he wanted to explain only in terms of causes of the degree operating at present; that is, he wanted to avoid ‘catastrophes’. Third, as a geologist he saw the earth as being in asteady-state, in which all periods are essentially similar to one another. Because they will prove important, I draw attention also to two major features of Lyell's programme. First, there is his theory of climate, which suggests, ‘without help from a comet’, that earthly temperature fluctuations are primarily a function of the constantly changing distribution of land and sea. Clearly this theory is actualistic, for it is based on such present phenomena as the Gulf Stream; it is also uniformitarian and supports a steady-state world picture. Second, there is Lyell's denial that the fossil record is progressive, his criticism of Lamarckian evolutionism, ostensibly on the grounds that modern evidence is against it (i.e. it fails actualistically), and his rather veiled claim that the origins of species will nevertheless prove in some way natural, that is, subject to causes falling beneath lawlike regularities in principle discernible by us.