Thanks! And thanks for watching. I'm glad you enjoy the videos!

+eammonful Yes, basically, all steming from Russell and Whitehead's type theory.

+This IS my name That sounds like a different version of non classical logic which questions the rules of the conditional. It is certainly a debate as to which logic we should use, but this one tries to be faithful to classical logic where any conditional with a false antecedant is true.

Carneades.org - Yes, it is a different version of non-classical logic designed to better reflect people's actual understanding of if statements. Literally everyone disagrees when first told that 'if a then b' is true if a is false. None of the usual explanations why - 'if a is false all bets are off', 'if a is false I wasn't lying', 'it's the principle of explosion' ( as if naming what you are doing is an explanation) work. I think my first paragraph above explains why they disagree and also explains many well known issues in logic, including for example the liar's revenge, which is undefined. [ edit: because any evaluating mechanism would go into an infinite recursive loop.] To clarify, the value U belongs to the meta-language, not the logic itself. There the sentences have no truth values at all. Great videos BTW. Keep em coming.