Puzzles
Why logic can never fully force you to accept its own conclusion
Lewis Carroll imagined the Tortoise refusing to accept a simple logical conclusion from Achilles unless Achilles also wrote down the rule that lets you draw it — and then refusing to accept that rule unless it, too, is written down as a premise. Where does the regress end?
Reveal the answer
It doesn't, and that's the point. No matter how many rules you add as premises, the Tortoise can always demand one more premise stating that this new rule applies. Carroll's 1895 dialogue exposed a real gap between accepting logical premises and accepting the inference that connects them — still discussed in philosophy of logic today.
— Lewis Carroll, What the Tortoise Said to Achilles — Mind, 1895 — public domain