Just a question of bookkeeping - online confidence update can be no less misleading, even if all facts are processed once. Million negative arguments can have negligible total effect if they happen to be dependent in non-obvious way.

online confidence update can be no less misleading

Not if processed correctly, but, of course, if you process incorrectly anything can happen.

Million negative arguments can have negligible total effect if they happen to be dependent

Agreed. Or even if they're independent, but small; or independent, but outweighed by ten million positive evidences.

On the other hand, each new argument might reduce the implicit quality of the arguers. Imagine a succession of wilder excuses, rather than a series of increasingly damning data, and you could justify the hawkish Freedonian's view.

Perhaps the way to avoid both of these strategies is to address new evidence in batches. First, you and the hawks add up all your arguments. Then you state them, and consider. A week later, you both state all the new evidence that's come to light since, address how it affects your interpretation of the old data, etc.

You don't want a situation like the evolution/creationism debate, in which creationists are ever ready to point out new gaps in the fossil record (apparently unaware that filling in a gap between A and C creates two new gaps -- between A and B and between B and C).

It's "one for you, one for me, two for you, one - two for me, three for you, one - two - three for you" your way wouldn't even fool Elmer Fudd.

Charlie, thanks.

Constant, virtually any modern hot-button political issue will do.

Byrne, the world's stupidest person may say the sun is shining but that doesn't make it dark out. Weak arguments don't go out the other side and become counterarguments.

Yes, but if my opponent makes arguments a seven-year-old can see through, that increases the probability that they are dishonest, and decreases my trust in any claims they may make. (If they present a complete line of reasoning, that of course isn't changed, but I mean claims of fact that I can't easily verify, or arguments leaving out several inferential steps.)

"Constant, virtually any modern hot-button political issue will do."

Actually, I think it would be pretty hard to come up with unambiguous examples of this, because what you're describing is not misbehavior that occurs in any given encounter, but a pattern over time in which an individual changes his own beliefs in the wrong way in response to the evidence. This is hard to demonstrate for at least two reasons. First, since it occurs over time rather than on a single occasion it's difficult to observe. Second, since what you're really talking about (the revision of one's beliefs) occurs inside a person's head there's the problem of gaining access to the person's head.

But if it is difficult to come up with unambiguous examples of it, then by the same token it is hard to observe in the first place. Any supposed observation of it will almost certainly require a large element of speculation about what is going on inside someone else's head.

What can we actually observe? Relevant to what you describe, we can observe two things:

1) We know generally that people's political views often harden over time. And since they do it in different directions, then in at least some cases the hardening is unlikely to be occurring for the right (the rational truth-seeking) reasons.

2) People do observably rehearse already-known support.

But (2) in itself is perfectly legitimate. Meanwhile (1) already has many explanations apart from the phenomenon that you are speculating exists. It's a much observed and much talked about phenomenon, and what you have done here is added only one more speculation about why it happens to the bulging library of explanations. While you are not necessarily wrong, at the same time as far as I can see there isn't all that much compelling evidence in favor of your speculation.

Even if you do want to integrate contrary evidence, it can be hard to do so quickly enough to continue a normal conversation, especially if the evidence is quite unexpected.

For example, suppose I have come to believe that in war X, the victory of the Reds against the Greens was always likely to happen. That is, from the first skirmish between the two sides, one could (with only the information about the two sides available at that point in time) confidently bet on the Reds winning. And the Reds did actually win.

If I know nothing of heuristics and biases, and someone counters my assertion about war X by mentioning the Hindsight Bias, then it may take me quite a long time to integrate this new evidence into my model of the world. I will need to think about the epistemic weight of heuristics and biases information, and ask how closely the conditions of tests of bias resemble my own. If my belief about war X depends in part on evidence about what professional historians believe, then I will have to consider the potentially thorny question of how much professional historians are subject to Hindsight Bias. Of course, my subjective probability in the inevitability of Red victory will go down, but the important question of how much it goes down cannot be answered so easily.

So, what we should often do in face-to-face discussion when we get new evidence is say, "please give me some time to integrate that new evidence into my model". This would be taken by many as a concession of defeat, just as would saying "After conditionalization on your evidence I have lowered by credence in P", and so will be hard for people to do in practice.

What can we actually observe? Relevant to what you describe, we can observe two things:

Also, we can observe (I read about a study that showed this) that people who intentionally seek out arguments that oppose their position tend to strengthen their belief in their position relative to people who only read friendly arguments. I forget exactly where I read this, unfortunately.

Chris,

Confirmation bias lab experiments show that people provided with mixed evidence wind up strengthening their initial beliefs. To clarify, are you saying that this study gave people the option to "intentionally seek out arguments that oppose their position," or recalling the ordinary confirmation bias experiments?

Carl, you might confuse people by addressing me by my real name when I'm not using it.

Unfortunately, my recollection of that study is weak. To the best of my memory, though, it was only a survey of people's blog/news reading habits combined with a test of dogmatism, not one where they actually instructed people in different groups to read more of fewer opposing arguments. I forget what the terms for these types of studies are.

Perhaps people tend to read low-quality opposing arguments only, for whatever reason, resulting in the effect I described above. They could even be reading really low-quality opposition for pure entertainment - I sometimes do this, but on reflection it's probably bad for me.

"Unfortunately, my recollection of that study is weak. To the best of my memory, though, it was only a survey of people's blog/news reading habits combined with a test of dogmatism, not one where they actually instructed people in different groups to read more of fewer opposing arguments." One worry would be that ideological enthusiasm leads to greater interest in politics in general.

"Perhaps people tend to read low-quality opposing arguments only, for whatever reason" Blogs may link to arguments from the opposing side in order to mock them, selecting those which are most objectionable from the perspective of their ideological allies.

I do remember a bit more detail about one study, though. Two different groups, one sympathetic to Israelis and the other to Palestinians (and maybe a third with no sympathies) were shown the same, fairly neutral article describing quite a bit about the conflict. Both groups held their positions more strongly after reading the article, and both groups thought the article was hostile to their positions.

both groups thought the article was hostile to their positions

They might both be correct about that.

Likely both groups hold false, self-serving factual beliefs and perceive denial of those beliefs (which a true article will inevitably contain) as hostile to them (and agreement with them as neutral).

this sort of abstract discussion about a possible error would greatly benefit from real and documented examples in which the described error cropped up

this OB comment

The problem, of course, is that by rehearsing arguments you already knew, you are double-counting the evidence This would be a grave sin even if you double-counted all the evidence.

Typo: there's a missing period between "evidence" and "This".

The real flaw here is that counting arguments is a poor way to make decisions.

"They don't have the ability to make said meteor strikes" is enough on its own to falsify the hypothesis unless you have evidence to the contrary.

As Einstein said about "100 Authors Against Einstein", if he was wrong, they would have only needed one.

Very cool. Less of a distinct mental handle, more of a subtle mental strategy one can find oneself executing across time.