Venn, John (1834–1923)

John Venn was a British symbolic logician and methodologist of science. He is known for having invented the method of Venn diagrams for judging the validity of categorical syllogisms and for advocating the ‘compartmental’ conception of categorical propositions which they display. He strongly defended Boole’s algebraic methods in logic by giving them clear logical meanings. He provided the first systematic formulation of the frequency theory of probability, and he showed the uncertainties inherent in the use of J.S. Mill’s inductive methods.