1925: Gottlob Frege dies

On 26 July 1925 the German philosopher and mathematician Gottlob Frege died in Bad Kleinen at the age of seventy-six. Though little celebrated in his own lifetime, Frege had quietly rebuilt the foundations of logic. His 1879 booklet Begriffsschrift introduced a fully formal language of quantifiers and predicates—the first notation powerful enough to express the intricate structure of ordinary mathematical reasoning.

Before Frege, logic had largely been a catalogue of syllogisms inherited from Aristotle. After him it became a precise calculus that could, in principle, be executed by machine. His distinction between sense and reference, his insistence on a sharp boundary between object and concept, and his unfinished attempt to derive arithmetic from pure logic supplied the conceptual toolkit later used by Russell, Whitehead, Carnap, Church and Gödel.

Those tools crossed directly into the digital age. When Turing formalised computation, when McCarthy designed Lisp, and when modern theorem-provers search for proofs, they all rely on the predicate calculus Frege invented. Even the knowledge-representation languages inside today’s large language models—graphs of entities, relations and quantified constraints—are distant descendants of the notation he sketched with his own hand.

Frege never saw an electronic computer, yet every AI system that reasons rather than merely pattern-matches walks a path he opened. On this anniversary we remember the quiet scholar whose death closed one chapter and whose ideas continue to animate the next.