Thanks for all the interesting responses.

Oh for heaven's sake, people, where did you all leave your common sense? There are at least THREE logical possiblities: true, false, or "unknown/unproven/unprovable". Is 2 an even number? True. Is 3 an even number? False. Is the Parallel Postulate true? Unknown, unproven. Forgive me if I have overlooked the Law of the Exploded Sausage.

"unknown/unproven/unprovable". — alan1000

Generally, if we are using standard logic, that'd apply for be belief, or knowledge, or some such; not truth.

I reckon sausages explode when they have too much water in them. Cook 'em slow, on low.