Also, I consider utilitarianism a faulty limiting base for economics and will explain. We can do better than Bentham, and JS Mill is barely understood by economists while Kant, well, you know....
Heck, William James along with Kant would form a superb philsophical base for economists or at least many economists. Chicago-ans I have no hope for; forgive me, I have enough to answer for at Confession already.
On utilitarianism I would distinguish between A) the theory in psychology that people act in order to maximize their happiness and b) the ethical view that people should act to maximize the sum of happiness in the world that is bet
A implies a very strong form of rationality since it is assumed that people do maximize utility not that they attempt to maximize utility. It is well know that the idea that people attempt to maximize their happiness has no testable implications.
It is also true that the hypothesis that people rationally maximize happiness has not testable implications and is not a scientific hypothesis. Any implications of utility maximizing models are implications of assumptions about the form of utility functions.
The proof is trivial. Imagine a person whose sole aim in life is to act in a many inconsistent with utility maximization. If there were any actions inconsistent with utility maximization, one would be utility maximizing for this individual. This is a logical contradiction, so there must be no action inconsistent with utility maximizing. QED
For those unconvinced by this argument, I note that all efforts to find implications of utility maximization are clearly based on the assumption which no one believes that utility functions are time seperable (revealed preference implies we enjoy eating no more at the beginning of a meal than after eating 1000 square meals in a row).
B on the other hand is another matter. For many years I thought that utilitarianism was the true description of what is right and what is wrong. I don't anymore, but I don't find the idea obviously absurd.
A is due to Bentham and is the foundation of (almost all) modern economic theory. B is due to Bentham's followers and is much detested by professional moral philosophers.