ChatGPT, Claude, Gemini all descend from GPT-2's decoder-only line, ianand explains

ianand · x · 2026-09-20

ianand recounts how GPT-2 took the decoder half of the Transformer and showed 'all you really need' is: the decoder, a single model for multiple tasks, prompting instead of task fine-tuning (the big unlock), and scale. These breakthroughs gave rise to every popular LLM today — all decoder-based descendants of GPT-2.

Related event: ianand's Thought Experiment: Jev, a Decision-Only AI From a Parallel Universe(9 posts)→

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