Anthropic researcher Emmanuel Ameisen explains why mechanistic interpretability remains necessary despite reasoning models outputting step-by-step chains of thought.
Opinion
Ameisen: Stochastic Parrots Label Ignores Complex Multi-Step LLM Reasoning
“It's, like, activating many different distributed representations, like, combining them, and sort of, like, doing something pretty complicated. And so, yeah, I think it's funny, because in my opinion, that's like, yeah, like, oh god, stochastic parrots is not …”
Insight
Ameisen: LLMs plan future tokens rather than operating purely myopically
“Language models are next token predictors is like a fact. Like that is what they do. They are trained to predict the next token. However, that does not mean that they myopically only consider the next token When they choose the next token, you can work on brea…”
Prediction Held up
Ameisen: Deceptive Backward Reasoning Exists in Base Pre-Trained Models
“I bet, I don't know how much I bet a hundred bucks. So somebody can like, they would get a hundred bucks from me if they prove that I'm wrong, that this behavior for a model that does a drink fine tuning, it also does it post pre-training.”
Assertion Supported
Ameisen: Multi-Hop Reasoning Circuits Are Extremely Similar Across Small and Large Models
“The way the circuit looks in Gemma, like a really small model is extremely similar to the way that it looks like a huge model, which that in itself is, I think like a pretty novel discovery. It's like, oh, you have these models that are like super different. Y…”
Disclosure
Ameisen: Anthropic's circuit tracing tool ignores attention heads and only decomposes MLPs
“These are just MLPs. So the model has both attention heads and multi-layer perceptions MLPs. We don't just do it. Like we completely ignore attention or like we don't try to decompose it at all. So there's some prompts where like all of the interesting stuff i…”
Assertion Supported
Ameisen: Swapping Internal Features Proves Single-Pass LLM Multi-Step Reasoning
“We claim that this is like the Texas representation. Let's get another one and replace it. And we just change like that feature in the middle of the model and we change it to like California. And if you change it to California, sure enough, it says Sacramento.…”