When it comes to questions of morality and ethics, we tend to ask what should be done.
When it comes to questions of preference, we ask about what we most desire.
In fact, it is always sufficient to ask: What is true?
With respect to ethics and desire, it is no longer widely believed that there exist true answers. But there do exist true answers.
We know there exist true answers because the true answers in ethics are consistent with the true answers about desire. As Aristotle wrote, "I have gained this by philosophy… I do without being ordered what some are constrained to do by their fear of the law.”
In social science, the concept is called triangulation. When multiple methods point to the same answer, we increase our confidence in it.
People spend too much effort trying to determine what they desire—do I wish to live in this city or that, do I wish to marry this person or that?—and much too little effort trying to determine what is true.
Seek only the truth and you will still have problems, but a large number of small, stupid problems will at least dissolve into a small number of large problems worth having.