Vaik interestingly refers to how Darwin used the Malthusian principle of competitive exclusion to cast his theory in axiomatic form. David Depew and Bruce Weber put it thusly: "Darwin's task as the sturcutre of the Origin of Species shows, was to refute the standing presumption, associated iwth Paley, that no natural law could account for the functional organic traits. By envisioning the environment as a a closed Malthusian, space, defiend by intense competition, Darwin provoked the presures and forces that could cause this effect, with no need to invoke any extrasystematic causes, least of all a divine one. In this Darwin's theory wasunderstood as delivering up the biological world to the same Newtonian framework that had already captured up the physical and chemical worlds."
But there is also the most interesting question, raised by Charles Peirce and many others afterward, about to what extent Darwin's logic of scientific explanation breaks with mechanism and introduces probabilistic reasoning at the core. Moreover, In breaking from the framework of natural theology--a break most brilliantly discussed by Dov Ospovat-- Darwin accomodated the occurence of chance variations, unpredictable phenomena, uncertain in outcome, and tending to no predetermined goal, divesting his theory of evolution of strict predictive power. We find here the distinction between explanation and prediction at the core of modern realist philosophies of science--I am thinking of Peter Manicas' discussion in his book on the philosophy of the social sciences.
Yours, Rakesh