Taken as an account of what we are, the C-theory answers ‘a cluster of capacities’. This conception of the nature of the self is open to a number of objections, and some of the most important are addressed in this chapter. Some philosophers (e.g., E. J. Lowe) maintain that it is illegitimate to specify the identity conditions of mental subjects in terms of mental states since the latter are ontologically dependent on (or modes of) the former. It is argued that this objection is less than compelling. Next it is considered whether the C-theory provides us with a believable account of the sort of things we are. Are such things really things — are they substances? It is argued that in one important sense at least, they are. By way of further support for the C-theoretical approach, it is argued there may be ‘power-worlds’ which consist of nothing but capacities. If such worlds can contain selves, there is no option but to construe them as collections of capacities.
Keywords: ontology, substance, dependence, modes, power-worlds, E. J. Lowe, C-theory