How do we know if we are reasoning correctly?
Consider, for example, this witty “proof” that a ham sandwich is better than eternal bliss: Nothing is better than eternal bliss. But, surely, a ham sandwich is better than nothing (despite Leviticus 11:7). Therefore, a ham sandwich is better than eternal bliss!
Admittedly, the error in *this* argument may be easy to see. But, of course, in more subtle lines of reasoning it is much harder to check for bugs. How, then, can we be confident, in general, that our arguments are fallacy-free?