Abstract

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.