The feasibility of hyperbolical doubt

cannot infer 'x cannot perish.' That is, from the claim that somethin cannot be both a person and not alive, we cannot infer that persons are immortal. Plto, however, uses 'immortal' in an equivocal sense. In (6) it means simply 'cannot die,' whereas in (7), it means what is usually meant, i.e., 'cannot perish.' And as he has pointed out, something which cannot admit death may perish. 5 Philosophical Studies, 18:46. l bid.