Moving debates to be about the motives of one side or another (in an adversarial context) is an implicit attack on credibility. Rather than making arguments about observable state in the world, the argument is now about whether one party should be paid any heed at all. It’s also typically going to be fruitless for the accused party: either they’re reflective enough to be fairly confident in what their beliefs are such that they immediately know that the accusation is false and are now faced with the chore of providing empirical evidence for something they’re very confident in, or they’re not and their epistemics on the matter are unlikely to be sharpened under adversarial pressure.
In either case, you’re not arguing about the thing you were arguing about anymore, you’re arguing about whether one of you should be arguing at all.
Motive arguments are arguments of last resort, when you’re confident that not only is your opponent wrong, but that they are so wrong for such fundamental reasons that there is no reason to pay their arguments any attention at all. And that can happen—sometimes a party is motivated in such a way that they’ll reliably generate bad arguments for a position. But that’s not a target you aim for if you want to have an ongoing dialogue.
(This assumes an adversarial context; in non-adversarial contexts motives can be questioned as a means of understanding. Politics is always adversarial.)
Moving debates to be about the motives of one side or another (in an adversarial context) is an implicit attack on credibility. Rather than making arguments about observable state in the world, the argument is now about whether one party should be paid any heed at all. It’s also typically going to be fruitless for the accused party: either they’re reflective enough to be fairly confident in what their beliefs are such that they immediately know that the accusation is false and are now faced with the chore of providing empirical evidence for something they’re very confident in, or they’re not and their epistemics on the matter are unlikely to be sharpened under adversarial pressure.
In either case, you’re not arguing about the thing you were arguing about anymore, you’re arguing about whether one of you should be arguing at all.
Motive arguments are arguments of last resort, when you’re confident that not only is your opponent wrong, but that they are so wrong for such fundamental reasons that there is no reason to pay their arguments any attention at all. And that can happen—sometimes a party is motivated in such a way that they’ll reliably generate bad arguments for a position. But that’s not a target you aim for if you want to have an ongoing dialogue.
(This assumes an adversarial context; in non-adversarial contexts motives can be questioned as a means of understanding. Politics is always adversarial.)
The more I think about it, the more it seems like the split here is just going to be adversarial vs cooperative contexts.