A simple utility function can be descriptive in simple economic models, but taken as descriptive, such function doesn’t form a valid foundation for the (accurate) prescriptive model.
On the other hand, when you start from an accurate description of human behavior, it’s not easy to extract from it a prescriptive model that could be used as a criterion for improvement, but utility function (plus prior) seems to be a reasonable format for such a prescriptive model if you manage to construct it somehow.
I agree with both those statements, but I’m not completely sure how you’re relating them to what I wrote.
Do you mean that the difficulty of going from a full description to a prescription justifies using this particular simpler description instead?
It might. I doubt it because utility functions seem so different in spirit from the reality, but it might. Just remember it’s not the only choice.
A simple utility function can be descriptive in simple economic models, but taken as descriptive, such function doesn’t form a valid foundation for the (accurate) prescriptive model.
On the other hand, when you start from an accurate description of human behavior, it’s not easy to extract from it a prescriptive model that could be used as a criterion for improvement, but utility function (plus prior) seems to be a reasonable format for such a prescriptive model if you manage to construct it somehow.
In that case, we disagree about whether the format seems reasonable (for this purpose).