Let me copy/paste my reply from the same discussion yesterday (https://news.ycombinator.com/item?id=18531650 https://news.ycombinator.com/item?id=18531650): Th

Let me copy/paste my reply from the same discussion yesterday (https://news.ycombinator.com/item?id=18531650 https://news.ycombinator.com/item?id=18531650): There's another "solution" to this paradox: if we assert something we are guided by a set of "conversational principles". For example, asserting "X implies Y" if we know that X is false is inappropriate. If X is false, "not-X" would be the appropriate assertion. According to this theory, there's nothing wrong with the truth-functional meaning of "X implies Y". We just need to take into account what is implied by asserting "X implies Y", rather than e.g. "not-X", or "X and Y". Same with disjunction: "X or Y" is true if we know that X is true. However, if we assert "X or Y", it is implied that we're not certain that X is true, otherwise we would have used "X", which is the simplest way to convey what that fact. This is known as Grice's Pragmatic Defence of Truth-Functionality.