There may be nothing more frustrating in the world than being unable to convince somebody that something is a tautology. You try as hard as you can to convince them that something is true by definition, but they persist in failing to see how you have designed the terms of the statement to be indistinguishable from the conclusion. Saying “Dogs are dogs therefore dogs are dogs” and having someone say, “Ah, but there are many kinds of dogs” is enough to drive one batty, if it happens often enough. Essentially, this is because the supposed point of contention is nothing of the kind – it is just a non sequitur that the other conversant thinks is some kind of rebuttal.
For some reason, training courses seem to spawn these sorts of logically agonizing discussions.
There is no strict difference between tautology and non-tautology. In the widest sense, tautology includes all analytic statements, that is, all statements where the adherence of the predicate to the object do so by the nature of the object itself. For example, “Balls are round”, is a good example of such a tautological analytic statement. However, other statements such as “Politics is the acquisition, maintenance, and exercise of power” are analytic in the sense that the predicates are claimed to be held to be true by the nature of the object (“politics”). Saying this statement is empirical seems wrong, because if “exercise of power” attaches to “politics” merely empirically then it would be enough to find a political system which did not involve the exercise of power. Problem there, you would not want to call it a political system – or you would have to revise what you mean by politics.
The point is, the relation between predicates and their object in the meaning of words blurs the boundary between empirical and analytic statements. And therefore there can be no clear line at which something becomes a tautology.
I’ve thought about this a bit more.
Perhaps the difference between tautology and non tautology is the contingency of the adherence of any predicate to an object, such that it remains properly that object. In other words, its a mereological problem – which parts of an object can be removed and have it still be that object? (“Object” as opposed to “subject”, not in the sense of a physical thing).
So, if I believed that the Canadian flag couldn’t be but red and white and you believed it could be those colours or other colours and still be the canadian flag, you might believe that the statement “the canadian flag is coloured red and white” to be a non tautological statement, whereas I would believe it was?
An example argument:
1) All government policy is made by domestic actors (Prime Minister, etc)
2) Foreign policy is government policy
Therefore,
A) Foreign policy is domestic policy.
Then, in response to that someone says:
1) But foreign policy is foreign! It’s right in the name!
Listen. Watch argument repeat until eyes start to bleed.
This argument is not stupid because its a tautology, but because the meaning of “domestic” is different in premise 1) and reply 1).
Tautologies are often present in mindbleedingly stupid arguments because disputes about tautologies are disputes about the meanings of words disguised as disputes about logical inferences.People are not good at sorting these out.
This discussion reminds me of this comic.
Also, this one.
Both feature Twisp and Catsby.
The foreign-policy-is-domestic-policy argument’s not even valid. It’s missing a premise that policy made by domestic actors is domestic policy, so strictly the problem isn’t about the different uses of domestic – although they are different uses of domestic.