7 ms·

I think that you are speaking of a logical tautology, while I am speaking of a linguistic tautology. If I am correct about this, we are both right. A logical t

I think that you are speaking of a logical tautology, while I am speaking of a linguistic tautology. If I am correct about this, we are both right. A logical tautology is, "A statement that is true by necessity or by virtue of its logical form." A linguistic tautology is, "A phrase or expression in which the same thing is said twice in different words." In formal debating, for example, you can call someone out for either type of tautology.

inimino 7y ago
Because we express logical statements in English, these two kinds of tautologies overlap. (If we were using a formal language we could express tautologies like !(A && !A) without using English.) If you say "All bachelors are unmarried", this is true both because of the meaning of the words, and because of the logical structure implied by the words. In either case, if you state a tautology, you state something which is true in all possible worlds, given the definitions of the words, at least. Someone can then call you out for stating a tautology, which is to state something that is vacuously true, that is, you've made a statement about the nature of reasoning itself, in any possible world, but you haven't said anything at all about the world we're actually in. So you're wasting your breath even though what you say is unassailably true. (Note that in mathematics, the tautologies are precisely the theorems with their premises or axioms! So this is by no means always useless.) The problem with calling out tautologies in common life, however, is that the danger of identifying a false tautology is very high. When someone says "Either X happened, or it didn't." you may be tempted to say "tautology!" but in fact they are probably making some kind of oblique point or highlighting a flaw in someone else's argument, etc. In other words, tautologies may be vacuous as statements about the world within a logical framework, but as speech acts in the real world, they always come with a motivation and that can usually be expressed in a non-tautologous way. For example, "A or not A" can be expanded charitably to "A or not A, and this is relevant to the topic at hand", which is not a tautology anymore. In this case, if you do something right, it's not extra hard, which is kind of a tautology. But there's a point in saying it, which is that it doesn't have to be that hard... if you do it right. And that's not true of everything or in every possible world, hence not a vacuous statement.

inimino 7y ago

Because we express logical statements in English, these two kinds of tautologies overlap. (If we were using a formal language we could express tautologies like !(A && !A) without using English.) If you say "All bachelors are unmarried", this is true both because of the meaning of the words, and because of the logical structure implied by the words. In either case, if you state a tautology, you state something which is true in all possible worlds, given the definitions of the words, at least. Someone can then call you out for stating a tautology, which is to state something that is vacuously true, that is, you've made a statement about the nature of reasoning itself, in any possible world, but you haven't said anything at all about the world we're actually in. So you're wasting your breath even though what you say is unassailably true. (Note that in mathematics, the tautologies are precisely the theorems with their premises or axioms! So this is by no means always useless.) The problem with calling out tautologies in common life, however, is that the danger of identifying a false tautology is very high. When someone says "Either X happened, or it didn't." you may be tempted to say "tautology!" but in fact they are probably making some kind of oblique point or highlighting a flaw in someone else's argument, etc. In other words, tautologies may be vacuous as statements about the world within a logical framework, but as speech acts in the real world, they always come with a motivation and that can usually be expressed in a non-tautologous way. For example, "A or not A" can be expanded charitably to "A or not A, and this is relevant to the topic at hand", which is not a tautology anymore. In this case, if you do something right, it's not extra hard, which is kind of a tautology. But there's a point in saying it, which is that it doesn't have to be that hard... if you do it right. And that's not true of everything or in every possible world, hence not a vacuous statement.