@misc{Lexicon of Arguments, title = {Quotation from: Lexicon of Arguments – Concepts - Ed. Martin Schulz, 29 Mar 2024}, author = {Geach,Peter}, subject = {Equivalence}, note = {I 189f Equivalence/Biconditional/GeachVsBlack: "is materially equivalent" is not synonymous with "if and only if". >Equivalence. "Three line" symbol ≡ is often read as "materially equivalent". But equivalence exists only between sentences, not names of sentences. Problem: Tom loves Mary ↔ Mary loves Tom" is only significant if "≡" (thee line) is read as "iff" (if and only if) rather than "materially equivalent".(⇔) cf. >Material, >Formal, >Description level, >Content, cf. >Formalism, >Formal language, >Formal speech, >Conditional.}, note = { Gea I P.T. Geach Logic Matters Oxford 1972 }, file = {http://philosophy-science-humanities-controversies.com/listview-details.php?id=201606} url = {http://philosophy-science-humanities-controversies.com/listview-details.php?id=201606} }