Introduction

If Aristotle is known for anything it is for his teleology. In the understanding of this issue the biology has proved especially useful, as one might well expect, since the primary subject of teleological explanation for Aristotle is the living thing – its development, structures, and activities.

What, then, is it, according to Aristotle, for a part of a living thing to be for the sake of an end, where that end is explanatory of the part's presence in an organism? And what is it for that part, or that organism, to come to be or to act for the sake of an end, where that end is not consciously aimed at? Earlier interpreters tended to assimilate the general living case to the human case, and they spoke for instance of potential souls and invisible entelechies guiding organic development – of ‘immaterial agencies’ of various sorts. But this, as J. H. Randall, Jr. (1960) pointed out, is to turn the final cause into an efficient cause. More recent interpreters agreed, and went on to speak as if the true causation involved in teleological processes was all at the material level.