Modern logic, or the logic that is loosely called "mathematical," began in a serious and systematic way with Augustus De Morgan's Formal Logic and George Boole's Mathematical Analysis of Logic, both published in 1847.

But a number of earlier writers were already "modern" in spirit, and of these, four stand out especially sharply—Leibniz, Euler, Lambert, and Bolzano.

See Also

Bolzano, Bernard; Boole, George; De Morgan, Augustus; Lambert, Johann Heinrich; Leibniz, Gottfried Wilhelm.