Comment by nothinkjustai

You are setting the bar in a way that makes “functional equivalence” unfalsifiable.

If by “functionally equivalent” you mean “can produce similar linguistic outputs in some domains,” then sure we’re already there in some narrow cases. But that’s a very thin slice of what brains do, and thus not functionally equivalent at all.

There are a few non-mystical, testable differences that matter:

- Online learning vs. frozen inference: brains update continuously from tiny amounts of data, LLMs do not

- Grounding: human cognition is tied to perception, action, and feedback from the world. LLMs operate over symbol sequences divorced from direct experience.

- Memory: humans have persistent, multi-scale memory (episodic, procedural, etc.) that integrates over a lifetime. LLM “memory” is either weights (static) or context (ephemeral).

- Agency: brains are part of systems that generate their own goals and act on the world. LLMs optimize a fixed objective (next-token prediction) and don’t have endogenous drives.