Daniel Kahneman
Psychologist whose fast-and-slow account of human thought, popularized in the book Thinking, Fast and Slow (link from graepel-2026-llms-dont-reason goes to the Penguin page for the book), is the frame two pages in this vault borrow. System 1 is fast, gut-level, effortless. System 2 is slow, step-by-step, deliberative.
The vault uses the distinction in two directions that pull against each other.
- system-one-models takes the name for a model category. TypeSafe’s Jev is sold as System One machinery: fast typed judgment, no deliberation, deliberately excluded from tasks past the 10-second test.
- graepel-2026-llms-dont-reason applies the split to whole LLMs and calls them “system 1 in action.” His argument, in chain-of-thought-faithfulness, is that chain of thought does not cross over into system 2, so the deliberate half of the pair is missing from current systems.
The shared frame is what makes the disagreement legible. TypeSafe says a fast judge plus a deliberating model on top is the right composition. Graepel says the deliberating model does not actually deliberate in the sense the frame promises. The two sources do not cite each other.
His academic details, the Nobel in economic sciences 2002 included, are not stated in any source this vault has read. This page records only the framing role he plays in the ingested sources.
Sources
- graepel-2026-llms-dont-reason (System 1/System 2 framing, Thinking, Fast and Slow link, read 2026-10-04)
- jev-is-incredible via system-one-models (the naming of the TypeSafe category)