ABILITIES ARE NOT DISPOSITIONS OF THE MOST COMMON SORT

The conception you have of a substance does not determine the extension of your concept. The extension is the extent of a certain substance in nature, not whatever you would identify as part of the extension. But the extent of which substance? That question is crucial. What determines, in the particular case, what particular substance one's perhaps stumbling, sketchy, and inadequate conception is aiming at? This chapter will make some progress toward answering that question. Further pieces of the puzzle will be added in Chapter 5, and the last pieces will finally settle into place at the end of Chapter 14.

Substance concepts are abilities of a certain kind. They are, in part, abilities to reidentify their assigned substances. How are these substances assigned? It is not a function of the cognitive systems as handed down by natural selection to identify any particular substance. Natural selection did not endow me with the ability to identify either 1969 Plymouth Valiants, or gasoline, or my husband. What I was endowed with was the capacity to acquire these abilities. Thus the general form of the question what determines the reference of a certain substance concept is: What determines what a learned ability is an ability to do? It will help to tackle the matter in this entirely general form.

The question of what abilities are deserves a lot of attention that it hasn't gotten.