Rod Hay
Sat, 01 Jul 2000 09:20:58 -0700
Ken. This is the same mistake that Carrol made in the first place. "It is raining" is not be a tautology. It can be true. Or it can be false. A tautology cannot be false. If you have another definition of a tautology, please give me a reference. Rod Ken Hanly wrote: > This is all mixed up, mostly incorrect. Some types of tautology are true because of >definitions. The types of tautologies recognised by > philosophers such as Kant. "All bachelors are unmarried" As Kant puts it the >predicate "unmarried" is included in the definition of > "bachelor". One could say that these sorts of statements are in a sense true by >definition. However a tautology such as "It is raining or > it is not raining" is not true by definition in any straightforward way. It is true >because of the manner in which the truth functional > operators > "not" and "or " work to form compound propositions. The fact that something you >write down is a tautology (or a contradiction) does not > relieve one of any burden of proof. Writing down "It is raining or it is not >raining" does not prove it is a tautology and the fact that > something is true does not show that it is a tautology. One has to prove that it is >a tautology. For example by constructing a truth > table. A tautuology is not simply true. It is necessarily true or true for formal >reasons not because of empirical facts. > Cheers, Ken Hanly > > Rod Hay wrote: > > > Yes, of course, Charles. > > > > Rod > > > > Charles Brown wrote: > > > > > >>> [EMAIL PROTECTED] 06/30/00 01:25PM >>> > > > After thinking better of my sarcastic tone to Carrol's message. Let me > > > explain. > > > > > > A tautology is a statement that is true by definition. That is, it is > > > always true. > > > > > > A = A is a tautology. > > > > > > A = B is not a tautology. That is, it might be false. > > > > > > Similarly all true statements are not tautologies. I.e., A = B might be > > > true. > > > > > > __________ > > > > > > CB: Sorry, couldn't help saying this since we are in a logical vein. You mean >"not all true statements are tautologies" , I believe. > > > > > > I agree with your post, though. > > > > > > _________ > > > > > > If all statements were tautologies, math and logic would be very easy. > > > Anything you write down would be true. No need to prove anything. > > > > > > -- > > > > -- > > Rod Hay > > [EMAIL PROTECTED] > > The History of Economic Thought Archive > > http://socserv2.mcmaster.ca/~econ/ugcm/3ll3/index.html > > Batoche Books > > http://Batoche.co-ltd.net/ > > 52 Eby Street South > > Kitchener, Ontario > > N2G 3L1 > > Canada -- Rod Hay [EMAIL PROTECTED] The History of Economic Thought Archive http://socserv2.mcmaster.ca/~econ/ugcm/3ll3/index.html Batoche Books http://Batoche.co-ltd.net/ 52 Eby Street South Kitchener, Ontario N2G 3L1 Canada