According to Aristotelian essentialism, the nature of an organism is constituted of a particular goal-directed disposition to produce an organism typical of its kind. This paper argues—against the prevailing orthodoxy—that essentialism of this sort is indispensable to evolutionary biology. The most powerful anti-essentialist arguments purport to show that the natures of organisms play no explanatory role in modern synthesis biology. I argue that recent evolutionary developmental biology provides compelling evidence to the contrary. Developmental biology shows that one must appeal to (...) the capacities of organisms to explain what makes adaptive evolution adaptive. Moreover, the specific capacities in question are precisely those that, according to Aristotle, constitute the nature of an organism. Essentialism 1.1 Aristotelian biological kinds Evolutionary anti-essentialism 2.1 Taxonomic anti-essentialism 2.2 Explanatory anti-essentialism Adaptation 3.1 Stability 3.2 Mutability 3.3 Phenotypic plasticity and adaptive evolution The natures of organisms Conclusion. (shrink)

In this essay I will argue for an interpretation of the remarks of Physics 1.1 that both resolves some of the confusion surrounding the precise nature of methodology described there and shows how those remarks at 184a15-25 serve as important programmatic remarks besides, as they help in the structuring of books 1 and 2 of the Physics. I will argue that “what is clearer and more knowable to us” is what Aristotle goes on to describe in 1.2—namely, that nature exists (...) and that natural things change—his basic starting-point for natural science. This, I shall hope to show, is the kind of “immediate” sense datum which Aristotle thinks must be further analyzed in terms of principles and then causes over the course of Physics books 1 and 2 to lead to knowledge about the natural world.[1] Such an analysis arrives at, as I shall show, a definition of nature not initially available from the starting-point just mentioned, and which is clearer by nature.[2] It is not my aim here to resolve longstanding debates surrounding Aristotle’s original intent in the ordering and composition of the first two books of the Physics, nor how the Physics is meant to fit into the Aristotelian corpus taken as a coherent whole, but rather to show that the first two books of the Physics, as they stand, fit with the picture of methodology for natural science presented to us in 1.1. [1] An interesting consequence of this, and one which I shall not pursue in this paper at any length, is that the progression from what is clearer to us and what is clearer by nature is by necessity a form of revision: i.e., the Physics should not be seen as a work validating the “starting-point” of 1.2 contra the monists, but a work which gradually builds to the language of matter and form as what is clearer by nature. [2] Viz., what we find at the beginning of 2.1: “this suggests that nature is a sort of source and cause of change and remaining unchanged in that to which it belongs primarily of itself, that is, not by virtue of concurrence”. (shrink)