|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._____________Annotation: The above characterizations of concepts are neither definitions nor exhausting presentations of problems related to them. Instead, they are intended to give a short introduction to the contributions below. – Lexicon of Arguments.|
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Identity of classes: symbolic: PxEfxyx - Identity/Relation-in-Extension: PxPyEfxyyxy - Identity/thre-place predikates: PxPyPzEfxyzyxyz - so you can go on and on up - or down to zero-place predicates(propositions).
Identity / Prior: a "zero-place predicate": (0) Efy i.e. "If f then y and if y then f" (spelling Lesniewski: E = equivalent) - which is the case when f and y are the case, or not case when f and y are not.
Truth value / Prior: so we imagine the term "truth value" for what we describe as the same, if the condition (0) is satisfied._____________Explanation of symbols: Roman numerals indicate the source, arabic numerals indicate the page number. The corresponding books are indicated on the right hand side. ((s)…): Comment by the sender of the contribution.
Objects of thought Oxford 1971
Arthur N. Prior
Papers on Time and Tense 2nd Edition Oxford 2003