[api]

That's what I mean by gathering information through dynamic interaction. It's not explicitly given the rules, but it can infer them. Interacting with an external system and sampling the result is still a way of gathering training data.

In fact this is ultimately how we've gathered almost all the information we have. If it's in our cultural knowledge store it means someone observed or experienced it. Humans are very good at learning by sampling reality and then later systematizing that knowledge and communicating it to other humans with language. It's basically what makes us "intelligent."

A brain in a vat can't learn anything beyond recombinations of what it already knows.

The fundamental limit on the growth of intelligence is the sum total of all information that can be statically input or dynamically sampled in its environment and what can be inferred from that information. Once you exhaust that you're a brain in a vat.