In a comment to a recent post, George W. asked:
Can man not desire that which is immoral? When you answer that objection, you answer your own objection to Ken.
Well, yes a person can desire that which is immoral.
This is because desires, in addition to being the only reasons for action that exist are, at the same time, means for the objective satisfaction or frustration of other desires.
As I have said, some desires are malleable - they can be molded through social forces such as praise and condemnation. This gives us reason to ask what reasons exist for using these social forces to promote some desires and inhibit others - to the degree that it is within our power to do so.
Desires are still the only reasons for action that exist. I would like to see a demonstration of the existence of any other type of reason for action. And the only sensible answer to a "should" question (as in, "Why should I perform this action?") is to provide a reason for action that exists.
These facts apply as much to the act of promoting or inhibiting particular desires in other, to the degree that desires are malleable, as they do to every other type of action. There are reasons for action that exist for promoting certain malleable desires and inhibiting others, but the only reasons for action that exist are other desires. The only sensible answer to the question of, "should we be promoting this desire or inhibiting that one" is to refer to reasons for action that exist - and that means appeal to its relationship to other desires.
Some might complain that this is circular - and it is. However, it is a form of circularity that philosophers call a virtuous circle - to distinguish it from the vicious circles we hear so much complaint about.
This response applies the same solution to desires that coherentist theories apply to beliefs. There is a question in epistemology (the study of belief) that asks how beliefs can be justified. The dilemma is that either we face an infinite regress of justification - justifying one belief on the basis of other beliefs that are, in turn, justified by appeal to still other beliefs. Or there are certain foundational "self evident" beliefs on which others can be built - such as the belief that a God exists and God created humans in his image.
Coherentists answer this problem with respect to beliefs by talking about a web of beliefs. What justifies a belief is its membership in a large and complex web of mutually supporting set of coherent beliefs.
This type of response is circular, in a sense, but philosophers recognize it as a virtuous circle - quite distinct from the vicious circles we have been warned against.
We are surrounded by virtuous circles. Not only are they used in coherentist epistemologies, they are found in language. A word gets it's meaning from the words that surround it, which get their meanings in part from the word being defined. Temperature effects evaporation rates, which effect atmospheric humidity, which effects temperature. Logicians and mathematicians employ virtuous circles in what they call recursive functions.
In the case of morality, malleable desires are evaluated by their relationship to other desires, which are evaluated by their relationship to still other desires, including the desire one is justifying. This works in the same way that beliefs are justified by their relationship to other beliefs, which are evaluated by their relationship to still other beliefs, including the belief one is justifying.
If somebody wants to reject this option, they are going to have problems far outside the field of ethics. They are going to have problems accounting for the possibility of justifying any belief, including mathematical and scientific claims.
Somewhere in this, I am supposed to discover the answer to my objection to Ken.
I suspect that George W. was expecting that I would either identify desires as those self-justifying foundational oughts, or I would evaluate desires according to some other standard, which would be justified in virtue of still some other standard, until I ended this infinite regress by appeal to some foundational ought (comparable to a foundational belief).
But these are not the only two options. There is a third option - one that is very widely used and accepted - of the virtuous circle. This virtuous circle allows for the possibility that we can desire that which is evil, just as we can believe that which is unjustified. This is true even though the only thing we can use to evaluate a desire is by appeal to other desires, in the same way that the only way we can justify a belief is by appeal to other beliefs.
So, I can account for a distinction between what we desire and what we ought to desire - the desires we have and the desires that we have reason to promote using social forces where the only reasons for action that exist are other desires.
However, Ken does not even address, let alone account for, the distinction between the instincts and intuitions we have versus the instincts and intuitions we ought to have. He is stuck with the instincts and intuitions we have, treating them as foundational oughts - a move which the Euthyphro question exposes as problematic at best.
Let me use this to give a direct answer to George's question.
Yes, people can desire that which is evil. That is, they can have malleable desires that tend to thwart other desires. Those desires thwarted are reasons for those others to act to inhibit the desire in question - to bring social tools to bear to make the desire-thwarting desires less common or weaker. Among those social forces are praise and condemnation. And the act of calling something evil is an act of condemnation.