Type theory: Restriction of formal systems to a type of reference that prevents symbols of one level (of one type) from referring to symbols of the same level (of the same type). This is intended to avoid paradoxes arising from the self-referentiality of the symbols or expressions used. Original proposals for type theories come from B. Russell (B. Russell, Mathematical logic as based on the theory of types, in American Journal of Mathematics 30 (1908), pp. 222-262). See also Self-reference, Circularity, Paradoxes, Russell's paradox, Stages, Branched type theory. _____________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. |