Alan Turing
Mathematician who formalized what "computation" means and, in 1950, asked whether a machine could think — the question the entire field still answers to.
Alan Turing (1912–1954) defined computation itself before there was much to compute. His 1936 paper on what became known as the Turing machine gave a precise, mathematical answer to "what can a machine calculate, given unlimited time and memory" — the theoretical floor every real computer, and every model trained on one, sits on. During the Second World War he led the team that broke the German Enigma cipher at Bletchley Park, turning that theory into working machinery under wartime pressure.
His most cited contribution to AI itself came in 1950, with the paper "Computing Machinery and Intelligence." Rather than trying to define intelligence, Turing proposed a test: if a human judge, conversing by text with a machine and a person, can't reliably tell which is which, the machine passes. The Turing test reframed the entire question — not "does this system think" but "does its behavior make the difference undetectable" — and that framing is still the implicit standard critics reach for when arguing about whether an LLMLLM (Large Language Model)An LLM is a large transformer trained to predict the next token on massive text corpora, then fine-tuned to follow instructions — the architecture behind GPT, Claude, Gemini, and Llama. "understands" anything.
Turing died in 1954, five years before the term artificial intelligenceAI (Artificial Intelligence)AI is the field of building systems that perform tasks normally requiring human intelligence — reasoning, perception, language, and decision-making. was coined at the Dartmouth workshop he never lived to see.
See also: Claude ShannonClaude ShannonEngineer who founded information theory, giving the field the mathematical vocabulary — bits, entropy, channel capacity — that loss functions and compression are still built on.
Learn more: History & Landscape · Wikipedia: Alan Turing
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Warren McCulloch
Neurophysiologist who, with Walter Pitts, proposed the first mathematical model of a neuron in 1943 — the ancestor of every neural network built since.
Claude Shannon
Engineer who founded information theory, giving the field the mathematical vocabulary — bits, entropy, channel capacity — that loss functions and compression are still built on.