INTRODUCTION

The nineteenth was logic's breakthrough century. At its beginning, logic had just been claimed by Kant, in justified ignorance of Leibniz's unpublished advances, not to have advanced since antiquity, and the laws of logic were soon to be submitted to the indignities of Hegel and to suffer the scorn of Mill. What started anachronistically in the 1820s with Richard Whately as a modest “back [beyond Locke] to Aristotle” movement in Oxford, trying to reinstate scholastic ways of doing logic after the long dark centuries since Ramus, inspired others lacking the desire to turn the clock back to reconsider logic and its role. This gathered momentum, and what began as a revival turned into a reform and then became a palace-storming revolution. Bolzano's obscurely published and tragically ignored 1837 masterpiece Wissenschaftslehre invented modern semantics, while ten years later in 1847 Boole and DeMorgan used mathematical methods and algebraic analogies to propel the study of inference out of the humanities and into mathematics.