Frederic Brenton Fitch (1908 – 1987) was an American logician who taught at Yale. He invented the Fitch-style for natural deduction. He is also famous for the paradox of knowability. The tag may also refer to natural deduction proof environments in Fitch-style calculus for giving and checking proofs.
For information about Frederic Fitch see the Wikipedia entry "Frederic Fitch": https://en.wikipedia.org/wiki/Frederic_Fitch.
For the knowability paradox see the following:
Brogaard, Berit and Salerno, Joe, "Fitch's Paradox of Knowability", The Stanford Encyclopedia of Philosophy (Winter 2013 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/win2013/entries/fitch-paradox/.
There are at least two Fitch-style proof checkers and associated textbooks:
- Dave Barker-Plummer, Jon Barwise and John Etchemendy, "Language, Proof and Logic" OpenProof Courseware: https://ggweb.gradegrinder.net/lpl with software available at https://ggweb.gradegrinder.net/lpl/features