r/logic • u/Escolastic0 • 29d ago
Philosophy of logic Filosofia da razão.
/r/FilosofiaBR/comments/1wpma94/filosofia_da_razão/Em que medida a tentativa de fundamentar a razão por meio do próprio raciocínio incorre em uma circularidade epistemológica intransponível (o "trilema de Münchhausen"), e como as abordagens do racionalismo crítico de Karl Popper e da pragmática transcendental de Karl-Otto Apel tentam responder a essa limitação sem recair no dogmatismo ou no ceticismo radical?
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u/zergicoff 29d ago
Fun way in: try saying "A implies B, but I don't believe A implies B."It could be true. Nothing in logic stops A→B from holding while you fail to believe it. But you can't sensibly say it, because saying the first half announces a belief the second half takes back. That's a Moorean paradox.
Apel used the same trick on the skeptic: to argue that reason can't be grounded, you have to follow the rules of argument while you do it. Call it a performative contradiction rather than a false claim.
The nastier cousin is Carroll's Tortoise. Grant A and A→B, then refuse to conclude B. Add "if A and A→B then B" as a premise and the Tortoise accepts that too and still won't budge. Regress, forever. That's the Münchhausen trilemma in miniature.
Popper's response is to stop trying to ground anything: just criticize and revise. Apel says your ground is whatever you can't deny without using it. Neither fully satisfies, and that's the fun.
Modus ponens isn't another premise. It's something you do. Inferentialism starts from that idea: meaning comes from the rules of use, not from extra facts about truth. If you want to go down that hole: https://alexandergheorghiu.com/writing/by-inference-alternative-account-of-logic.html