Boris Hennig

Starting from the idea that functions are formally similar to actions in that they are described and explained in a similar way, so that both admit of an accordion effect, I turn to Anscombe’s insight that the point of practical reasoning is to render explicit the relation between the different descriptions of an action generated by the accordion effect. The upshot is, roughly, that an item has a function if what it does can be accounted for by functional reasoning. Put differently, a part of a system has a function if what it does is a functional part of what the system does.

The distinction between teleology and teleonomy that biologists sometimes refer to seems to be helpful in certain contexts, but it is used in several different ways and has rarely been clearly drawn. This paper discusses three prominent uses of the term “teleonomy” and traces its history back to what seems to be its first use. This use is examined in detail and then justified and refined on the basis of elements found in the philosophy of Aristotle, Kant, Anscombe and others. In the course of this explication, it will also be shown how the description of end-directed processes relates to their explanation.