|Identity: Two objects are never identical. Identity is a single object, to which may be referred to with two different terms. The fact that two descriptions mean a single object may be discovered only in the course of an investigation.|
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Identity/Kripke/Pauen: Thesis: identity must be necessary if it is to be identity at all - E.g. either it is true in all worlds that C-fiber irritation is identical with pain or it is not true in any - they are not identical then.
VsKripke/Pauen: there seems to be an argument against it: heat is also a rigid designation expression (kinetic energy) but we can imagine a world in which we have heat sensation without molecular motion - KripkeVsVs: then it is about heat sensation, not heat. - Imaginability/Pauen: is crucial for Kripke. - The imaginability of pain, which are not irritated C-fibers, eliminates the identity. - Today largely accepted: that psychophysical identity, if it exists at all, must be necessary.
Grundprobleme der Philosophie des Geistes Frankfurt 2001