So a valid and sound argument can “beg the question”. That’s the point I was making.
And that’s a good point so far as it goes, but one of the main measures of an argument is whether it works to get others to accept the conclusion. Valid and sound arguments that work are preferable; some such offer the audience no reason to accept the conclusion. I like sound arguments featuring a logical inference apart from merely the principle of identity.
In my opinion, the error in reasoning is implicit in the presentation of an argument that is intended to convince others of the conclusion. It is not reasonable to convince somebody of the truth of a conclusion by using that very conclusion as a premise in a circular argument recommending the conclusion in turn.
Well, but as you know, any valid argument has the conclusion implicit in the premises.
Right, but typically not in one premise, and it is that condition that results in the fallacy of begging the question.
It may not be obviously implicit, but logically the conclusion cannot contain information that wasn’t in the premises already. This is the problem with validity and “begging the question”.
That problem is resolved when one distinguishes between an argument that takes truths and through logical inference produces a conclusion that is different from either/any of the premises alone.
That said, I do agree with you that there is something wrong with many arguments that “beg the question”. The problem is not that they are invalid (let’s assume the arguments presented are always valid) but that the premises are unsupported. Clearly, an argument that is intended to convince others must do so in part by convincing them that the premises are true. But not everyone will be convinceable in this way—indeed, I would be willing to argue that there is no possible argument which will be always convincing.
Granted; there is such a thing as “invincible ignorance.”
Similarly, there is no premise that everyone will take as true. So given any set of premises, some people will claim that those premises in that argument “beg the question” in themselves being unsupported.
I must point out that the fallacy of begging the question applies in particular to the point at issue. For example, if we argue whether incompatibilist free will can exist coherently in a given scenario (for the sake of argument), then we fallaciously beg the question by assuming causal determinism in a premise. A reductio ad absurdum that misrepresents the issue doesn’t help us, after all. We might “beg the question” by assuming that LFW exists as we attempt to reduce it to absurdity, but the attempt requires us to make the assumption for the sake of argument. An unsupported premise is not the same as the fallacy of begging the question (see “fallacy of the contested premise” for the distinction).
Again, I’m not claiming that there’s nothing wrong with begging the question. What I would claim is that sometimes begging the question is a problem (where the premises are amenable to convincing counterargument) and sometimes begging the question is not a problem (where the premises are amenable to unconvincing counterargument).
I think you need to focus more on the way arguments focus on particular points of contention. Suppose two folks think the Earth is flat but want to argue whether it would be at least consistent to imagine a spheroid Earth. Neither accepts the premise that the Earth is flat; neither would regard their arguments as sound. In that sense, they both “beg the question”—but the relevant sense of the fallacy of begging the question occurs if the argument somehow assumes its conclusion in one of the premises. That is, one is asking the other to concede the point at issue from the outset rather than convincing him through customary logical inference.
That is the problem with begging the question.
Of course, what counts as convincing and unconvincing will depend on the person doing the counting.
Indeed. What would advertisers and lawyers do if fallacious arguments lost their ability to convince others?