Guide · 37 episodes · updated 2026-09-06

Chain of thought: what the visible reasoning actually does

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Does a model's written chain of thought reflect how it actually reasons, or just decorate the answer?

Chain of thought asks a model to write out intermediate steps before answering, and those often function as real working memory: strip them away and accuracy can collapse by dozens of points. The papers keep circling back to whether the visible is the real computation or a plausible story told after the fact. Some show reasoning chains causally driving decisions, enabling , self-correction, and safety ; others find the same traces are post-hoc rationalizations, fail to across languages, or degrade predictably past a certain depth. There is broad agreement that removing or explicit reasoning hurts performance, but real disagreement over whether what gets read off a trace can be trusted as an honest account of what the model is doing.

What chain of thought means

Chain-of-thought prompting asks a model to think step-by-step before answering, dramatically improving performance on reasoning-heavy tasks. The trick works because the model is now using its own intermediate tokens as working memory, but the visible chain is not always the real chain.

The episodes (37)

Newest first. Each line is what that paper contributed to the question.

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Intro written by Anthropic's Claude Sonnet 5; episodes selected and edited by Garrett Casey. Episode notes come from each episode's own analysis. How PaperDive is made.