In the first chapter of Jon Elster's Solomonic Judgments, he argues that choice without preference is not an important practical issue. He contends that no one cares which of two apparently identical soup cans on the supermarket shelf is chosen. The only way a choice like this will matter is if there are differences in the two soup cans, i.e., one has more broth than the other, etc.I may be stupid, but I'm like Elster -- I just don't see a problem here. The scenario assumes that our only motivation is to purchase the can, and that there are no constraints other than preference on choice. It ignores the motivation the post mentioned (the financial motivation to only buy one can), time-constraints, motor constraints, etc., which all factor in to the optimal (which is really what "rational" is in this case) choice. If you get rid of all of those, then there's probably no need to choose a can in the first place. In fact, I bet that if you threw all of those into an Ideal Observer model, what you'd find is that the model either chooses one of the two cans all of the time (which would probably be due to the motor constraints) or choose each can 50% of the time (because the motor constraint doesn't apply). Humans, because we're not ideal observers (our behavior is suboptimal) will have all sorts of noise in our data if forced to make the choice a bunch of times, but it would probably be pretty close to the ideal observer model assuming that the initial conditions were the same every time (which would be impossible, but you get the point).
I may have missed the point, but the problem of the choice without preference is that we can choose either soup can A or soup can B and satisfy our desire for buying soup. Since both soup cans will satisfy our desire, then rationality tells us to purchase both soup cans. If we think like this, though, we could potentially become poor very quickly. (Perhaps using the example of very similar cars on a new or used car lot would bring the problem to the fore.) So, it is not rational to purchase both cans. What seems to follow is that reason tells us to do something it is not rational to do.
Have I missed the point of choice without preference, or has Elster missed an important component of this difficult problem?
Maybe Buridan's Ass is an interesting logical problem, even though it's not an interesting practical problem, and probably can't shed any light on the decision-making process (though it apparently sheds some light on Romance novels -- see here) other than that we have reasons for making decisions that go beyond the independent attractiveness of two options (duh!), but I can't imagine how it would be. For it to be even a logical problem would require that we pretty much remove all of the motivations to make the choice in the first place (a similar point for is made by Richard at Philosophy, etcetera). If it were still a problem, logical or otherwise, even given all of the constraints and other motivations that factor into a choice like this (or with them all removed), here's how I would solve it: I'd pick up both cans and then make a choice when I got to the cashier. By that time, choosing one should be more optimal than choosing the other (maybe because it's closer to me in the cart). I think that's pretty much the solution people much smarter than me have traditionally come up with (e.g., the solution of Otto Neurath, which just involved flipping a coin). As for the ass, since he probably doesn't have a shopping cart, or a coin, he's just going to have to suck it up and make a choice.