I've always considered language just another form of logic (a very fuzzy one of course). To say something sensical in any language requires (almost by definiti

I've always considered language just another form of logic (a very fuzzy one of course). To say something sensical in any language requires (almost by definition) some logical consistency. Otherwise you get non-sequiturs and insane ramblings. The greater the coherency of a narrative (e.g. paragraph-to-paragraph like GPT-3, vs. just word-to-word like a Markov chain), the greater degree of consistent logical underpinnings are needed. So that a tool trained to produce coherent human writing by necessity has embedded in itself a tool for logical reasoning is not too surprising (not to say it isn't impressive!).