| > This is very strange.. Those are not what tautologies are. > I think you just want to say "I know that already!" > “All humans are mammals” is held to assert with regard to anything whatsoever that either it is not a human or it is a mammal. But that universal “truth” follows not from any facts noted about real humans but only from the actual use of human and mammal and is thus purely a matter of definition. [1] Moving on. I assumed parent was trying to make (non-vacuous) statements, firstly because he was replying to a comment, and secondly because he followed them up with "There's nothing vacuous about this." > Proposing definitions to terms could never be tautological. If you treat them as statements, the tautologies clearly appear by substituting the terms' definitions in: * To have a (thing which can vary) is to assume that something can vary. * To be a (something that can make a difference) is to assume something can make a difference. But if parent was just defining his terms, then let's hear those terms used in non-vacuous statements. [1] https://www.britannica.com/topic/tautology |