Rod Hay
Sat, 01 Jul 2000 12:29:32 -0700
Yes Ken. I misread your post. Sorry. An inconvenient line break. And a too quick reading and provocation at your claim that my post was mostly wrong. Your example is in fact the same example that Carnap uses in his Introduction to Symbolic Logic. And yes, most tautologies cannot be recognised immediately. I used the simplest example of a tautology that I could think of. My point was that the statement that Charles made "all equations are tautologies" and Carrol's agreement and extension that all syllogism are tautologies, was confusing the truth value of a statement with the concept of a tautology. And except for the grammatical error that Charles pointed out, I don't see how what you wrote contradicts what I wrote. It merely extends it. Carnap: "Sentences which thus are true for all possible value-assignments of their constituent parts are said to be tautological sentences or tautologies. Ken Hanly wrote: > My post does not claim that "It is raining" is a tautology. It claims that "It is >raining or it is not raining" is a tautology. Of course "It is > raining" is not a tautology but dependent for its truth upon weather conditions. >Reread my post. A tautology cannot be false but the "cannot" is > a logical cannot. There may be some things that cannot be false because of the >facts. Perhaps the comment about capitalism's ultimate demise is > arguably of that sort. The distinction we are discussing here though is the subject >of some philosophical debate. Authors such as Quine question > the distinction. Anything can be made tautologous he claims. > I think some leftists are experts at starting theoretical discussions that seem >to turn on the facts but soon it is clear > that the doctrines are part of a core theoretical stance that is not going to accept >any facts as refuting. WHat seems to be contrary to the > theory will turn out to be from ministrieses of misinformation, running dogs of >ministries of misinformation and so on,. > Cheers, Ken Hanly > > Rod Hay wrote: > > > 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 -- 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