Formal reasoning is defined, informal reasoning very much isn't.

The difference between thinking and reasoning is that I can "think" that Elvis is still alive, Jewish space lasers are responsible for California wildfires, and Trump was re-elected president in 2020, but I cannot "reason" myself into those positions.

It ties into another aspect of these perennial threads, where it is somehow OK for humans to engage in deluded or hallucinatory thought, but when an AI model does it, it proves they don't "think."