"Picking one charity and sticking to it" would follow from most utility functions I'm able to imagine
I think your imagination is rather limited then. Charitable donations as a signaling activity are one example. If you donate to charity partly to signal to others that you are an altruistic person and use your choice of charity to signal the kinds of things that you care about then donating to multiple charities can make perfect sense. Donating $500 to Oxfam and $500 to the WWF may deliver greater signaling benefits than donating $1000 to one of the two as it will be an effective signal both for third parties who prioritize famine and for third parties who prioritize animal welfare. If you are partly buying 'fuzzies' by donating to charity then donating to the two charities may allow you to feel good whenever you encounter news stories about either famine or endangered pandas, for a net benefit greater than feeling slightly more virtuous on encountering a subset of stories.
Between evolutionary psychology, game theory, micro and behavioural economics and public choice theory to name a few research areas I have found a lot of insightful explanations of human behaviour that demonstrate people rationally responding to incentives. The explanations often reveal behaviour that appears irrational according to one version of utility makes perfect sense when you realize what people's actual goals and preferences are. That's not to say there aren't examples of biases and flaws in reasoning but I've found considerable practical value in explaining human action through models that assume rational utility maximization.
Incidentally, I don't believe that demonstrations of preference reversal falsify the kind of model I'm talking about. They only falsify the naive 'fully conscious rational agent with a static utility function' model which is not much worth defending anyway.
From the relative frequency of your scenario vs mine, I'd say my theory wins this example hands down. :-)
Your theory fails to account for the exceptions at all though. And I have had great success losing weight by consciously arranging my environment to reduce exposure to temptation. How does your theory account for that kind of behaviour?
Aaah! No, no. I originally used "picking one charity" as a metaphor for following any real-world goal concertedly and monomanically. Foolishly thought it would be transparent to everyone. Sorry.
Yes, incentives do work, and utility-based models do have predictive and explanatory power. Many local areas of human activity are well modeled by utility, but it's different utilities in different situations, not a One True Utility innate to the person. And I'm very wary of shoehorning stuff into utility theory when it's an obviously poor fit, like moral ...
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Ah wahned yah, ah wahned yah about the titles. </some enchanter named Tim>
(Oh, a note: the idea here is to establish general rules for what sorts of decisions one in principle ought to make, and how one in principle ought to know stuff, given that one wants to avoid Being Stupid. (in the sense described in earlier posts) So I'm giving some general and contrived hypothetical situations to throw at the system to try to break it, to see what properties it would have to have to not automatically fail.)
Okay, so assuming you buy the argument in favor of ranked preferences, let's see what else we can learn by considering sources of, ahem, randomness:
Suppose that either via indexical uncertainty, or it turns out there really is some nondeterminism in the universe, or there's some source of bits such that the only thing you're able to determine about it is that the ratio of 1s it puts out to total bits is p. You're not able to determine anything else about the pattern of bits, they seem unconnected to each other. In other words, you've got some source of uncertainty that leaves you only knowing that some outcomes happen more often than others, and potentially you know something about the precise relative rates of those outcomes.
I'm trying here to avoid actually assuming epistemic probabilities. (If I've inserted an invisible assumption for such that I didn't notice, let me know.) Instead I'm trying to construct a situation in which that specific situation can be accepted as at least validly describable by something resembling probabilities (propensity or frequencies. (frequencies? aieeee! Burn the heretic, or at least flame them without mercy! :))) So, for whatever reason, suppose the universe or your opponent or whatever has access to such a source of bits. Let's consider some of the implications of this.
For instance, suppose you prefer A > B.
Now, suppose you are somehow presented with the following choice: Choose B, or choose a situation in which if, at a specific instance, the source outputs a 1, A will occur. Otherwise, B occurs. We'll call this sort of situation a p*A + (1-p)*B lottery, or simply p*A + (1-p)*B
So, which should you prefer? B or the above lottery? (assume there's no other cost other than declaring your choice. Or just wanting the choice. It's not a "pay for a lottery ticket" scenario yet. Just a "assuming you simply choose one or the other... which do you choose?")
Consider our holy law of "Don't Be Stupid", specifcally in the manifestation of "Don't automatically lose when you could potentially do better without risking doing worse. It would seem the correct answer would be "choose the lottery, dangit!" The only possible outcomes of it are A or B. So it can't possibly be worse than B, since you actually prefer A. Further, choosing B is accepting an automatic loss compared to chosing the above lottery which at least gives you a chance of to do better. (obviously we assume here that p is nonzero. In the degenerate case of p = 0, you'd presumably be indifferent between the lottery and B since, well... choosing that actually is the same thing as choosing B)
By an exactly analogous argument, you should prefer A more than the lottery. Specifically, A is an automatic WIN compared to the lottery, which doesn't give you any hope of doing better than A, but does give you a chance of doing worse.
Example: Imagine you're dying horribly of some really nasty disease that know isn't going to heal on its own and you're offered a possible medication for it. Assume there's no other medication available, and assume that somehow you know as a fact that none of the ways it could fail could possibly be worse. Further, assume that you know as a fact no one else on the planet has this disease, and the medication is availible for free to you and has already been prepared. (These last few assumptions are to remove any possible considerations like altruistically giving up your dose of the med to save another or similar.)
Do you choose to take the medication or no? Well, by assumption, the outcome can't possibly be worse than what the disease will do to you, and there's the possibility that it will cure you. Further, there're no other options availible that may potentially be better than taking this med. (oh, assume for whatever reason cryo, so taking an ambulance ride to the future in hope of a better treatment is also not an option. Basically, assume your choices are "die really really horribly" or "some chance of that, and some chance of making a full recovery. No chance of partially surviving in a state worse than death."
So the obviously obvious choice is "choose to take the medication."
Next time: We actually do a bit more math based on what we've got so far and begin to actually construct utilities.