Multiple independent arguments: resistors not capacitors

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I somehow pulled something in my back last night so forgive whatever writing comes through the Vitamin V. Anyway, I've been wanting to write about interpreting arguments through the filter of confirmation bias. Let me give you an example: someone is trying to convince you that eating meat is unethical. Halfway through the argument they also tell you that eating meat is correlated with a higher rate of heart attacks. How should you interpret this? On the one hand, this is an additional argument in favor of going vegetarian—presumably you wish to stay alive and so maybe if it's healthier you'd stop. Even if health isn't enough reason for you to switch, maybe the ethical argument had some impact but wasn't quite enough to push you over the edge, but combined with the health argument it's sufficiently convincing.

Here's the problem, though: whether eating meat is ethical has no bearing at all on whether eating meat is healthy (and mostly the other direction too, though of course if eating meat is unhealthy then there is a utilitarian argument against it being ethical). And yet people who believe eating meat is unethical are going to be a lot more likely to believe that eating meat is unhealthy (I would call this a form of confirmation bias). So, you immediately need to heavily discount the claim that eating meat is unsafe. Now, obviously, you can evaluate the arguments for yourself, but in real discussions you don't have time to completely evaluate every argument, so to some extent you rely on the fact that the person you're talking to has evaluated them and found at least the minimal factual assertions to be correct. Worse yet, you should consider discounting the claim that it's unethical: maybe there's some third reason that your interlocutor really has for being vegetarian and their ethical commitments are also the result of confirmation bias, so perhaps you should discount both their arguments, as well as any other arguments they happen to offer.

To give another example, Mrs. G recently had a conversation with a friend who's planning to vote Republican and one of the reasons he gave was some alleged political scandal involving Obama. I'm deliberately not naming it because it's irrelevant; it could just as well have been an alleged scandal involving McCain, and that's the point. Anyone who has been in the public sector for a while is going to have done some things that are questionable, or at least can be questioned. So, when tou an argument that Politician X's behavior was bad and therefore you shouldn't vote for them, it's important to figure out whether the argument is being used for support or ilumination. One test here is whether the person offering the argument thinks that any of X's primary opponents aren't corrupt. If they answer is "no", then this is suggestive (though not conclusive) of confirmation bias. What's more likely, that all of party X is corrupt or that you're the victim of confirmation bias and treating the sins of people you don't agree with more seriously than the sins of people you don't? And again, when someone offers me a lame reason for voting against X, it makes me discount their entire argument.

So, when someone offers me a bunch of logically independent reasons for policy X, my response isn't to treat them as additive, but rather that they're just throwing arguments at the wall to see what will stick, and I take them less seriously, not moreso. It's like resistors in an electrical circuit: multiple resistors in parallel have less resistance than any of the components, not more.


"Vitamin V" was Herb Caen's (San Francisco Chronicle) term for a vodka martini and I got a giggle seeing you use it. But alas! you think it's Vicodin. Heck, that stuff probably wasn't even invented when Caen started using the term....

Carry on. Just thought I'd say hi. :D

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