  There is a long tradition, dating at least from Reid (1785), for arguing that the identity of persons over time is not a matter of convention or degree in the way that the identity of other (complex) substances is and that this shows that the self is a different kind of entity from any physical body. Criticism of these arguments and of the intuitions on which they rest, running from Hume to Parfit (1970: 1984), have left us with an inconclusive clash of intuitions. The argument under consideration and which, possibly, has its first statement in Madell (1981), does not concern identity through time, but the consequences for identity of certain counterfactuals concerning origin. It can, perhaps, therefore, break the stalemate which faces the debate over diachronic identity. The claim is that the broadly conventionalist ways which are used to deal with problem cases through time for both persons and material objects, and which can also be employed in cases of counterfactuals concerning origin for bodies, cannot be used for similar counterfactuals concerning persons or minds.