Wednesday, May 21, 2008

Arguing by Degrees

Now that I think of it, a better way to make my point may be to replace talk of 'all or nothing' belief with credences or degrees of belief.

Even if you ultimately reject an argument, it may be that you were antecedently disposed to have greater credence in the premises (conjoined) than in the conclusion. Upon having this mild inconsistency pointed out to you by the valid argument, you will presumably revise your credal state by some appropriate combination of reducing your credence in the premises and raising your degree of belief in the conclusion.

If an argument can, in this way, be expected to lead many to rationally revise upwards their degree of belief in its conclusion, then it ipso facto has rational force (and is not question begging), in relation to this community of inquirers. This may be so even if their resulting credal state still falls short of full-blown belief.

I note that this approach also helps to refute a similar claim I addressed last year, namely:
No rational argument then can be constructed to ever change a person’s mind, because we can never get to premises that people must accept.

My earlier points refute it well enough, of course, but 'credence' talk makes it even clearer. For this reminds us that we may change a person's mind even without changing their full-blown beliefs (though we may do that too). Even if we merely sway them from thinking a view wildly implausible to instead thinking it moderately unlikely, that is clearly dialectical progress.


  1. I think the non-credence way was better. (I'm in that small minority of people who think that there is no such thing as a degree of belief, and that credences are just fictions invented to make certain kinds of arguments seem less absurd than they otherwise would; so take that evaluation however you will.) But either way, I think the position mentioned in the last sentence is important. As someone who does a lot of history of philosophy, I'm often forced into the position of trying to nudge people from the view "Position X is utterly absurd" to at least "Position X is still wrong, but it has interesting features." Very hard to do. But it's often confused with trying to convince people of the view "Position X is right", when sometimes even I think it's pretty clearly wrong. We often do need to remind people that there are evaluations between "Correct" and "Insane"; even where they recognize the distinction, they don't always act on it.

  2. We might distinguish a couple of things here. One is the point that there are intermediate evaluations along the [probability of] truth dimension between 'certainly correct' and 'certainly incorrect'. A distinct point is that we might evaluate arguments along other dimensions besides their probability of soundness. [I recently mentioned the ontological argument as an example of an argument that is certainly unsound, but nonetheless of great philosophical interest. I don't think it should lead anyone to increase their credence in its conclusion, however, so it's a bad argument in the sense I'm concerned with here.]


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