These are very atheoretical thoughts about where the disagreement dispute is at.
Local vs global evaluation of agents
At the lunch referred to in the earlier post, we were talking about what kinds of people are drawn to the equal weight view of disagreement, as opposed to views that give peer disagreement less weight. One thought was that it was people who are more confident in their own opinions who dislike the equal weight view.
On reflection, I don’t think that’s right. What really motivates me is that I prefer to use very localised judgments about the reliability of a person. I know in my own case that I have any number of intellectual blindspots, some of them extremely narrowly drawn. (I’m pretty good on evaluating baseball players for instance, unless they happen to play for the Red Sox or Yankees.) When I see someone making an odd judgment on _p_, I don’t think that they’re in any sense ‘intellectually inferior’, I just think they have odd views about _p_. And that’s exactly the kind of question that I would use their views on _p_, and not any independent views they may have, to answer.
Who is being more dogmatic?
Relatedly, I’ve heard a few people describe the equal weight view as a more conciliatory view, and alternative views as less conciliatory. I think this is a mistake twice over.
For one thing, think about the case where you think _E_ is not strong enough evidence for _p_, because there is a just realistic enough alternative explanation for _E_, but your (apparent) peer is simply dismissive towards these alternative explanations. He (and it’s easiest to imagine this is a ‘he’) says that only a crazy sceptic would worry about these alternatives. The equal weight view now says that you should firmly believe _p_, and agree that worries about the alternative, although coherent, are inappropriate. That doesn’t seem particularly conciliatory to me. (Nor does it seem rational, which might be why we never see much discussion of the equal weight view’s use in dismissing seemingly legitimate doubts.)
For another, think about things from the perspective of the irrational agent. For example, consider a case where a rational agent’s credence in _p_ is 0.8, and an irrational agent’s credence is 0.2, and antecedently they regarded each other as peers. I say that both of them should move to a credence of around 0.8 – or maybe a touch less depending on how strong a defeater the irrational agent’s judgment is. The equal weight view says that the rational agent’s credence should move down to 0.5. That is, if I’m the irrational agent, I can accuse the other person of a rational error unless they come half-way to my view. That’s despite the fact that my view is objectively crazy. A view that says that when you’re wrong, you should concede ground to the other person seems *more* conciliatory than a view that says that you should demand that everyone meet you halfway, even people with a more accurate take on the situation.
Me on political philosophy vs me on epistemology
In an old _Analysis_ paper on “land disputes and political philosophy”:http://brian.weatherson.org/notsawold.pdf, I was rather hostile to a view on land disputes that purported to resolve any conflict in a way that was fair to both parties. Partially my hostility was because I didn’t think the resolution was particularly fair. But in part it was because the appropriateness of the resolution really relied on this being a genuine conflict in the first place. It seemed to me then, as it seems to me now, that identifying situations where two parties have an equal claim to something (in that case land, in this case perhaps truth or rationality) is much harder than figuring out what to do in such a case.
Somewhat paradoxically, I have a weak preference for us *not* having too nice a mechanism for solving disputes where parties have a genuinely equal claim. That’s because if we had such a mechanism, we’d be over-inclined to use it. And that would mean we’d end up treating as equals, or more exactly as equal claimants, parties who really weren’t equal in this respect. I think in practice, the way to resolve most disputes is to figure out who is right, and award the prize to them.
Independence
One of the motivations behind some versions of the equal weight view is that we should only use evidence that is ‘independent’ of the dispute in question to decide whether someone is a peer or not. (Nick Beckstead correctly notes this in the comments on the earlier post.) I think this is all a mistake. And as evidence for that, I present the case of “Richard Lindzen”:http://en.wikipedia.org/wiki/Richard_Lindzen.
Lindzen is an atmospheric physicist at MIT, and was involved in writing the 2001 IPCC assessment on climate change. That doesn’t make him the world’s foremost expert on climatology, but it does suggest he’d know more about it than me. Surprisingly, he turns out to be a climate change denier. (I’m not sure whether ‘denier’ or ‘delusionist’ is the correct current term; I have trouble keeping up.) I think that’s crazy, and I think the objective evidence, plus the overwhelming scientific consensus, supports this view.
Now what should an equal weight theorist say about the case? They can’t say that I can use the craziness of Lindzen’s views on climate as reasons to say he’s not a peer (or indeed a superior), because that would be giving up their view.
They could try saying that I could appeal to the views of other experts, but I think that misses the point. After all, the other experts are just more evidence, and Lindzen has that evidence just as much as I do. And he dismisses it. (I think he thinks it’s a giant conspiracy, but I’m not sure.) So even if I’m going to believe in global warming because of my reliance on other experts, I have to say that I’m going to trust my judgment of the testimonial evidence over someone else’s judgment of that very same evidence, even though I thought antecedently he would know better than me what to do here.
We could try saying that his dismissal of all the experts proves he is irrational. After all, he’s not an equal weight theorist! (That won’t bear much weight with me, but it might with the equal weight theorists.) But this is just to concede the point about independence. After all, we are judging his ability to make judgments about _p_ not on independent grounds, but on grounds of how well he does on _p_. That seems like a violation of independence.
The debate, at this point, seems to resemble the complaint I made in “Disagreeing about Disagreement”:http://brian.weatherson.org/DaD.pdf. The equal weight theorist needs to treat the status of their theory of disagreement very differently to other epistemological theories. If Lindzen refuses to infer to the best explanation in this case, say, then we can’t dismiss his views unless we can criticise him on independent grounds. But if he refuses to take his peer’s judgments as strong evidence, we don’t need independent grounds to criticise that. This double standard seems objectionable.
Disagreement about evidence vs disagreement about conclusions
I’ve been trying to think about which cases I’m actually disposed to change my views in the face of peer disagreement. I think they are largely cases when there is a legitimate dispute about just what the *evidence* is. So think of some cases, common in sports, where we are trying to judge a simple factual question on the basis of visual evidence. The most common of these, in my experience, are so-called ‘bang-bang’ plays at first base. In that case we have to decide whether a baseball or a base runner got to a point earlier. And even with the situation right in front of us, this can be surprisingly hard.
Here are two salient facts about that case.
First, it is very hard to say, in a theoretically satisfying way, just what the evidence is in the case. I’m not a phenomenalist about evidence, so I don’t really want to say that the evidence is just how the case seems to us. In some sense, if it is possible to just see that, let’s say, the ball arrived first, then that the ball arrived first is in some sense part of my evidence. Perhaps I don’t know it is part of my evidence, and perhaps I don’t even believe it is true, but it is plausibly evidence for me.
Second, in a case like this, deferral to peers seems like a very natural thing to do. If there are six people watching TV, and I have a different opinion about what happened to the other five, then I’ll usually conclude I was wrong. Let’s assume, at least for the argument, that this is rational.
Here’s a hypothesis. It’s rational to defer to peers when it is unclear what your evidence is. It is less rational to defer to peers when it is unclear what the right response to the evidence is, at least when the peers have the wrong response. To consider the analogy above, I shouldn’t be so willing to defer to peers about disagreements about who will win the game, when we all have the same evidence about that.
The strongest cases for the equal weight view in the peer disagreement literature are, I think, cases where the evidence is not entirely clear. (At least on an externalist view of evidence.) Perhaps those are the cases where the equal weight view is correct.