This got to be too long to be a comment on Michael C’s post. People sometimes criticize utilitarianism for being "inapplicable," or for entailing that you shouldn’t try to use it as a decision procedure. I don’t think there is any way to interpret this criticism such that utilitarians should worry about it.
First of all, it is a category mistake to criticize utilitarianism for not being a decision procedure. Utilitarianism is a statement of necessary and sufficient conditions for an act to be morally right. No statement of necessary and sufficient conditions is a decision procedure. Imagine buying a cookbook that purported to give you a procedure for making a cake, and the cookbook just gave you necessary and sufficient conditions for something to be a cake. You could rightly complain that you aren’t interested in the philosophy of cake, you just want to make a cake, and you wanted the book to tell you how to do that. (For this reason it is misleading to say that it is only "sophisticated" utilitarians who claim that their view is not a decision procedure. All utilitarians must say so on pain of committing a category mistake.)
But some will press the objection. They might say that the project of coming up with a decision procedure is really the important thing, or is at least another important thing, that moral philosophers ought to be doing. And nothing about utilities is likely to be part of the correct decision procedure. In most cases, thinking about utility when deciding what to do will not help you do the right thing, and often it might hurt. So even if utilitarianism were correct as a criterion of moral rightness, there can be no correct and distinctively utilitarian decision procedure.
This is a bad objection. There can be no correct decision procedure of any sort, if a decision procedure is supposed to tell you, under any circumstances, what procedure to follow – how you ought to deliberate – in order to act rightly (or in order to have the best chance of acting rightly). What procedure would be best to follow for the person who has less than 2 seconds to decide whether to save the children, and also best for the person who has 3 months to decide which charity he should send his money to? The correct procedure would have to be possible to follow in a very short time, and also give the right results in cases where more time for deliberation is available. It would have to be best to follow for someone with no common sense, and also best for someone with lots of common sense; for someone good at math, and someone who sucks at math…etc. That seems impossible.
If there is no correct decision procedure of any sort, then it can be no objection to utilitarianism that there is no correct and distinctively utilitarian decision procedure. Do people have something else in mind when talking about decision procedures? Is there any criticism in this neighborhood that utilitarians should worry about? And is there any reason to think philosophers should spend time trying to come up with a correct decision procedure?