In making his distinction between revisionary and descriptive metaphysics, P.F. Strawson wrote that the former has some value provided that its "partial vision" is at the service of the latter, "which needs no justification at all beyond that of inquiry in general." (Individuals, p. 9) Perhaps we feel no need to ask what justification there is for inquiry in general. But if we do recognize any such need, then we discover that inquiry is self-justifying...