I have a tentative answer for the second question of “Why this representation?”. Given that a set of preferences can be represented as a probability function and a utility function, that seems computationally more convenient than using two probability functions, since then you only have to do half of the Bayesian updating.
Another part of this question is that such a set of preferences can usually be decomposed many different ways into probability and utility, so what explains the particular decomposition that we have? I think there should have been a selection pressure for humans to have a common prior, to the extent possible, and move as much as possible of the differences in preferences into the utility function, since that would facilitate communication and sharing of information. It seems that if we had common priors, and I have a lot of information about something (and you trust me), I can just tell you my posterior beliefs, instead of having to give you all of the raw information and let you recompute your own posterior beliefs.
I have a tentative answer for the second question of “Why this representation?”. Given that a set of preferences can be represented as a probability function and a utility function, that seems computationally more convenient than using two probability functions, since then you only have to do half of the Bayesian updating.
Another part of this question is that such a set of preferences can usually be decomposed many different ways into probability and utility, so what explains the particular decomposition that we have? I think there should have been a selection pressure for humans to have a common prior, to the extent possible, and move as much as possible of the differences in preferences into the utility function, since that would facilitate communication and sharing of information. It seems that if we had common priors, and I have a lot of information about something (and you trust me), I can just tell you my posterior beliefs, instead of having to give you all of the raw information and let you recompute your own posterior beliefs.