2. Identity in logic and the classical law of thought

Abstract

‘Identity in logic and the classical law of thought’ explains that Leibniz’s law of the identity of indiscernibles conforms to the laws of logic. It defines identity as strict self-sameness, but raises the difficult problem of what counts as the same. By framing identity as a semantic problem and introducing a distinction between the meaning of an expression (sense) and what it stands for (reference), Frege provided a partial solution to it, but vagueness continues to pose a major difficulty for the logic of identity. Non-Western logics that differ from the Aristotelian tradition offer an alternative by viewing every concept as including its own negation as a property, rather than the absence of properties.