What Do You Think of Presuppositionalism?

[Angrboda]

Rasetsu, what would you think of this objection I thought of?:

Humans define what it means to have valid reasoning, so it doesn't make sense to ask 'Do you reason that your reasoning is valid?', because then we're just applying something we ourselves define. Wouldn't it be like asking Plato "How do you KNOW that knowledge is a justified true belief?"

I'm drunk and psychotic tonight, but off the top, I'd say the math and logics are self-evidently self-verifying. The epistemology isn't foolproof, but our best wisdom points to it being reliably true. (To fulfill that promise requires a comprehensive philosophy which I haven't seen. Systematizing appears to have gone the way of the Dodo bird.) (This in a way, asks whether Platonism or nominalism rules. IMHO, neither, because neither asserts a coherent view of the nature of "meaning.")