Abstract

An objection is offered to the Frege-Russell definition, which identifies the number 1 with the set of all unit sets. It is argued here that the identity conditions for sets require that if any member of a set had not existed, the set itself would not have. Therefore, had any object whatever not existed, the unit set containing it would not have either, and thus the set with which the definition identifies 1 would not have. But then, 1 either would not have existed or would have been a different entity than it is, and it is argued that neither alternative is acceptable.