In place of my own interests, I now have to take into account the
interests of all those affected by my decision. This requires me to
weigh up all these interests and adopt the course of action most
likely to maximize the interests of those affected. Thus at least at
some level [in very unusual circumstances] in my moral reasoning I must choose the course of action that has the best consequences, on balance, for all affected. ~ p 13 Practical Ethics
Preferences need to have weight or else it doesn't modify behavior at all. For example, a malnourished child's preference to be fed has to outweigh a banker's desire to own a second yacht for preference utilitarianism to be coherent.
Or substitute the banker's yacht for your desire to go to a movie. My point is that it appears like preferences need to be weighed or else preference utilitarianism just means everyone does what they were going to do anyway. Preferences would cancel out: a professor not wanting each student to cheat versus any one of the students who wants to cheat; a son preferring to lie, where his mother preferring him to tell her the truth.
The best action is what satisfies the most preferences or desires. From the literature on this, it appears many preferences are applicable per situation. This, opposed to say, the most obvious preference or an over-residing type of preference.
Are all preferences equal? Not all preferences can be treated equally,
however. A serial killer has a desire to kill innocent people and a
medical student has a desire to give people medical assistance, but
the satisfaction of the latter desire would lead to the satisfaction
of the desires of many others, while the satisfaction of the former
desire would decrease the preference satisfaction of many
others--those that he kills. So preferences should be ordered in
importance as follows:
(1) Preferences whose satisfaction contributes to the preference
satisfaction of others
(2) Preferences whose satisfaction is neutral to the preference
satisfaction of others.
(3) Preferences whose satisfaction decreases the preference
satisfaction of others.
Moreover, we ought to factor in the strength [my emphasis] of
preferences or desires. Clearly, all else being equal, the
satisfaction of a strong desire should outweigh the satisfaction of a
mild desire. ~ Victor's Utilitarianism lectures part I
In other words, there is a preference calculus.
Something different below?