Decidability of Euclidean geometry#Some_decidable_theories).
I don't know where Landsburg gets the claim that we can know all the truths of arithmetic.
Note that Landsburg is thus also incorrect in saying "we can never know all the truths of euclidean geometry".
A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).
ETA: It would seem that rationality quotes are no longer desired. After several days this thread stands voted into the negatives. Wolud whoever chose to to downvote this below 0 would care to express their disapproval of the regular quotes tradition more explicitly? Or perhaps they may like to browse around for some alternative posts that they could downvote instead of this one? Or, since we're in the business of quotation, they could "come on if they think they're hard enough!"