I am taking a metafysics class1 and last lectur’s topic was time travel. That is an issu i sort of like but i dislike the way people discuss it, in general. Ther is a widespred lack of clarity and lack of training in the relevant logics (that is, modal logics: alethic logic and temporal logic). […]

Some people think that the identity notion is captured by the second proposal above. I think we need two notions of identity. I will not discuss that now. Strict identity For all things, for all things, for all predicates, that x and y are strictly identical logically implies that that x has predicate F is […]

For all things, for all locations y, for all locations z and for all times t, that a thing is in location y at time t and that y is not identical to z logically implies that that thing is not in location z at time t. (∀x)(∀y)(∀z)(∀t)((Lxyt∧x≠y)⇒¬Lxzt) Idea The principle is meant to capture […]