The most recent set of questions I have received on desire utilitarianism contained the following two questions.
6. What do you think are the greatest objections to desire utilitarianism?
2. If desire is a brain state, it requires a nervous system. So, I assume bacteria, plants, and lower animals have no morally relevant desires. But how do we tell when a creature has morally relevant desires, especially since you make no distinction between conscious and unconscious desires?
Okay, the greatest objection to desire utilitarianism says that there are no desires.
The reason we have for holding that there are no desires is because we have too many questions to answer about what a desire is and who has them. Some people predict that when we come up with a theory of intentional action that can handle all of these questions, that this theory will be so radically different from the theory of beliefs and desires that the later will face elimination.
One of the questions is: At what point do creatures actually acquire desires. Let’s say that plants and amoeba have no desires. Do worms? Oysters? Lobsters? Sharks/ Insects? Frogs? Snakes? Cattle? It seems difficult to draw a line somewhere.
Do thermostats have desires? Is it reasonable to explain what a themostat does as having a desire for the temperature of the room to be at 72 degrees, a belief that it is at 68 degrees, and thus it forms the intentional act of heating the room.
Explain what a desire is such that it rules out this possibility needs to explain what desires are in such a way that it makes sense of this ruling.
Another relevant question to ask is: Under what conditions do machines acquire desires?
I do not have answers to these questions. I decided, when I encountered these issues that I did not have the resources to investigate them separately. Instead, I would take the most widely held view among philosophers of mind that we have today. However, the popularity of a view has little to do with whether or not it is correct. That demands a different sort of evidence.
One of the faults with objections to the thesis that intentional actions are caused by the beliefs and desires is that there are no solid competing theories. There are a lot of people who are complaining that desire-based reasons has serious faults – faults enough to suggest that it may be replaced. However, that is not the same as having a theory that actually purports to do a better job of explaining intentional action (or whatever intentional action proves to be in fact).
On the bright side, there is work to be done, for anybody who might have an interest in doing it. I would not want this work to take the form of “proving that desire utilitarianism is the best theory around”. Instead, it should take the form of looking at intentional action (or what we currently conceive of as intentional action), improving on the belief-desire model of intentional action, then seeing how desire utilitarianism (or some other theory) deals with those objections.
There is one thing that can be said for the belief-desire model, however. We do use these terms in an attempt to explain and predict events in the universe that are very important to us – the behavior of others. These have come to be very valuable tools. Their usefulness, then, is one argument to be made that they refer to something real, and provide a challenge that any competing theory must match.