Logic 100: A Short History of Logic - MGTOW

A prequel to my series on logic. In this video we take a whirlwind tour of the last 2500 years in the development of logic.

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The person who is generally credited as the father of logic is the ancient Greek philosopher Aristotle. Aristotle’s predecessors had been interested in the art of constructing persuasive arguments and in techniques for refuting the arguments of others, but it was Aristotle who first devised systematic criteria for analyzing and evaluating arguments.

Aristotle’s chief accomplishment is called syllogistic logic, a kind of logic in which the fundamental elements are terms, and arguments are evaluated as good or bad depending on how the terms are arranged in the argument. But Aristotle also deserves credit for originating modal logic, a kind of logic that involves such concepts as possibility, necessity, belief, and doubt. In addition, Aristotle catalogued several informal fallacies.

After Aristotle’s death, another Greek philosopher, Chrysippus, one of the founders of the Stoic school, developed a logic in which the fundamental elements were whole propositions. Chrysippus treated every proposition as either true or false and developed rules for determining the truth or falsity of compound propositions from the truth or falsity of their components. In the course of doing so, he laid the foundation for the truth functional interpretation of several logical connectives and introduced the notion of natural deduction.

For thirteen hundred years after the death of Chrysippus, relatively little creative work was done in logic. The physician Galen developed the theory of the compound categorical syllogism, but for the most part philosophers confined themselves to writing commentaries on the works of Aristotle and Chrysippus. Boethius is a noteworthy example.

The first major logician of the Middle Ages was Peter Abelard. Abelard reconstructed and refined the logic of Aristotle and Chrysippus as communicated by Boethius, and he originated a theory of universals that traced the universal character of general terms to concepts in the mind rather than to “natures” existing outside the mind, as Aristotle had held. In addition, Abelard distinguished arguments that are valid because of their form from those that are valid because of their content, but he held that only formal validity is the “perfect” or conclusive variety.

After Abelard, the study of logic during the Middle Ages flourished through the work of numerous philosophers. A logical treatise by William of Sherwood and the Summulae Logicales of Peter of Spain became the standard textbook in logic for three hundred years. However, the most original contributions from this period were made by William of Ockham; famously known for Ockham’s Razon. Ockham extended the theory of modal logic, conducted an exhaustive study of the forms of valid and invalid syllogisms, and further developed the idea of a metalanguage, a higher-level language used to discuss linguistic entities such as words, terms, and propositions.

Toward the middle of the fifteenth century, a reaction set in against the logic of the Middle Ages. Rhetoric largely displaced logic as the primary focus of attention; the logic of Chrysippus, which had already begun to lose its unique identity in the Middle Ages, was ignored altogether, and the logic of Aristotle was studied only in highly simplistic presentations. A reawakening did not occur until two hundred years later through the work of Gottfried Wilhelm Leibniz. Leibniz, a genius in numerous fields, attempted to develop a symbolic language or “calculus” that could be used to settle all forms of disputes, whether in theology, philosophy, or international relations. Leibniz is credited alongside Sir Isaac Newton with the invention of the mathematic discipline of Calculus. As a result of this work, Leibniz is sometimes credited with being the father of symbolic logic. Leibniz’s efforts to symbolize logic were carried into the nineteenth century by Bernard Bolzano.


In the middle of the nineteenth century, logic commenced an extremely rapid period of development that has continued to this day. Work in symbolic logic was done by many philosophers and mathematicians, including Augustus De Morgan, known for De Morgan’s Law, George Boole, where our word Boolean comes from, William Stanley Jevons, and John Venn, known for the Venn diagram. At the same time a revival in inductive logic was initiated by the British philosopher John Stuart Mill.