William Stanley Jevons
British logician, economist, and philosopher of science. Born in Liverpool, and learned at University College, London. As a disciple of de Morgan, he contributed to the development of symbolic logic created by Boole and de Morgan.
He noticed the mechanical character of logical reasoning; he proposed the "logical alphabets" for Boolean logic (which utilize, in the contemporary terminology, the disjunctive normal form of propositional logic), and devised the "Logical Machine" (with a keyboard for input) which perfoms the process of logical reasoning for the Aristotelian syllogism, somehow extended to disjunctive propositions too.
He was also a powerful advocate of the probabilistic induction based on the "inverse method" due to Bayes and Laplace, and defended by de Morgan in the Britain. He emphasized the uncertain and probabilistic character of scientific knowledge. The Principles of Science (1874) , in which his view is systematically expounded, is important as one of the classical works on the philosophy of science in the 19th century.
See Jevons's Inverse Method