Well, sort of - but we use "if" in day-to-day as a different thing to the material implication in logic. I've yet to run into a person using 'if and only if' in

Well, sort of - but we use "if" in day-to-day as a different thing to the material implication in logic. I've yet to run into a person using 'if and only if' in a way that doesn't map to the material equivalence, though, but I'm sure it must happen Actually, this wikipedia article for has got a specific section about that https://en.wikipedia.org/wiki/Material_conditional https://en.wikipedia.org/wiki/Material_conditional Edit: I also just learned abou the 'Wason selection task' from that link. Cool stuff. https://en.wikipedia.org/wiki/Wason_selection_task https://en.wikipedia.org/wiki/Wason_selection_task