The goal of ambitious mechanistic interpretability (AMI) is to fully understand how neural networks work. While some have pivoted towards more pragmatic approaches, I think the reports of AMI's death have been greatly exaggerated. The field of AMI has made plenty of progress towards finding increasingly simple and rigorously-faithful circuits, including our latest work on circuit sparsity. There are also many exciting inroads on the core problem waiting to be explored.

The value of understanding

Why try to understand things, if we can get more immediate value from less ambitious approaches? In my opinion, there are two main reasons.

First, mechanistic understanding can make it much easier to figure out what's actually going on, especially when it's hard to distinguish hypotheses using external behavior (e.g if the model is scheming).

We can liken this to going from print statement debugging to using an actual debugger. Print statement debugging often requires many experiments, because each time you gain only a few bits of information which sketch a strange, confusing, and potentially misleading picture. When you start using the debugger, you suddenly notice all at once that you’re making a lot of incorrect assumptions you didn’t even realize you were [...]

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Outline:

(00:38) The value of understanding

(02:32) AMI has good feedback loops

(04:48) The past and future of AMI

The original text contained 1 footnote which was omitted from this narration.

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First published:
December 5th, 2025

Source:
https://www.lesswrong.com/posts/Hy6PX43HGgmfiTaKu/an-ambitious-vision-for-interpretability

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Narrated by TYPE III AUDIO.

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