[FOM] A textbook on logic with natural deduction

[paul@personalit.net]

Dag Prawitz's two short pieces on natural deduction in A Philosophical 
Companion to First-Order Logic, edited by R. I. G. Hughes (Hackett 
Publishing, 1993), are excellent. 

E. J. Lemmon's excellent Beginning Logic book is also printed by Hackett 
for under $20 -- better price than the $80 mentioned in a previous post.

Cheers,

-paul