I have received a comment from a member of the studio audience that gives me an opportunity to review some of the elements of desire utilitarianism.
Where I wrote that a creature that only has desires that are fulfilled by having slaves and has no desire that would (could) be thwarted by such a desire was an entirely imaginary creature, Kevin wrote:
[T]his should not be difficult to imagine. Prior to the Civil War, such a view was quite commonplace.
Saying that a view is commonplace is not the same as saying that a view is true. It may have well been the case that southern slave owners before the civil war believed that slavery only fulfilled desires and thwarted none. However, this would not make it true. (Nor, by the way, would I even hold that they believed such a thing.)
DU seems a theory that is compatible with just about any moral vision one could have. If my desire is fulfilled by owning slaves, then DU can be used to justify that (even if in a utilitarian fashion which says that more desires are fulfilled by ownership of slaves than not).
DU does not say, "X is (morally) justified if and only if X fulfills the most and strongest of my desires." That would be a theory of practical 'ought', not a theory of moral 'ought'. DU says, "X is (morally) justified if a person with good desires – a person with those desires that people generally have reason to promote – would do X (in the case of moral obligation) or could do X (in the case of moral permission)."
Since people have many and strong reason to cause in their neighbors an aversion to depriving others of their liberty, it follows that a person with good desires would be averse to depriving others of liberty, which means a person with good desires would have an aversion to holding slaves or supporting an institution of slavery, which means that slavery is immoral.
You don't offer any persuasive reason for DU to take an anti-slavery stance except for a very strange assumption that you know the slaveowner's desires better than he.
First, the only type of 'persuasive reason' I am interested in here is whether or not a proposition is true. DU does not base moral claims on the desires of the slaveowner. It may well be the case that (a) slavery is wrong (people generally have many and strong reasons to promote an overall slavery, and (b) a particular slaveowner has no reason to care about this. Such a slave owner will go ahead and do that which is wrong. We cannot 'persuade' him not to do so. However, our inability to persuade him is no proof that slavery is, in fact, not wrong.
One of the biggest problems with moral theory is the realization that giving a person reason to do x means finding a reason that would be persuasive to that particular person. I am not sure any of the reasons you are giving would be persuasive to the slave-owner (especially if he were living in a country that was slave-owning).
There is an equivocation here built into the phrase "giving a person a reason to do X". The equivocation is between correcting a false belief that the agent might have whereby doing X actually fulfills the most and strongest of the agent’s desires, but he does not know it.
DU holds that there is more than one way to "give a person a reason to do X". One is rational persuasion that certain propositions are true. Morality does not use this method.
Namely, let's say that you want to persuade me to do X.
Let us also assume that I will only do that act that will fulfill the most and strongest of my desires, given my beliefs – including altruistic desires. This is not egoism. This is consistent with the claim that a person's desires can be desires for the well-being of other people.
Primarily, there are three types of persuasion that concern us here.
Persuasion Type 1: Practical 'ought'. You can 'give me a reason' by pointing out that a belief of mine is false. I do not want to do X, but this is because I do not realize that X will result in Y, and Y will, in fact, fulfill the most and strongest of my desires. By correcting my belief you give me a reason to do X.
Unfortunately, it might be the case that what fulfills the most and strongest of my desires is something seriously harmful to others. I simply might enjoy giving people pain, in which case "giving me a reason to do X" would mean "helping me to realize that I can inflict more and greater pain by doing X." You have given me a reason, but it is not the type of reason typically associated with morality.
Persuasion Type 2: Threats Another way you can give me a reason to do X is by threatening me. "If you do not do X, then I will make you suffer." You have now given me a reason to do X. It is easier here to look at cases in which you might want to give me reason NOT to do something. For example, you wanted to give me a reason NOT to rape your child. You cannot persuade me that I have no desire to rape your child, but you can still threaten to thwart as many of my desires as you can if you discover that I have raped your child.
Even in this case, your threat is only good insofar as (1) you catch me, and (2) you have the power to carry through on your threat. In addition, these types of threats are no different than threats that you might face from people who might want you to turn over your wallet, help in the roundup and extermination of Jews, or work in the cotton fields without pay.
Persuasion Type 2': Religion. Religion answers two of the three problems associated with threats – the problem of catching the perpetrator and of having the power to punish the perpetrator.
There is a significant difference between saying, "If I discover that you raped my daughter I will seek to thwart as many of your strongest desires as I can," and "If my invisible friend who knows everything and can condemn you to an eternity of flaming torture with a thought catches you raping my daughter, He will make you suffer."
The problem with this method is that these omniscient and omnipotent friends do not exist. The commandments that these entities hand down are not the declarations of a perfectly just being. They are the inventions of the people who invented the God to begin with. The inventors of Gods are neither perfectly wise nor perfectly good. They will give these Gods moral views that are mistaken in some cases. In other cases, they will use God himself as a threat – "Serve God or suffer for eternity" is simply another way of saying, "Serve me or suffer for eternity."
Persuasion Type 3: Altering desires There is still another way in which you can give me a reason to do X. This does not involve giving me a true belief, or threatening me. Instead, it involves altering my desires.
If you were to give me an aversion to rape itself, then you have given me a reason not to commit rape. If you give me an aversion to stealing then you give me a reason not to steal, and if you give me a love of freedom then you give me a reason not to take the freedom of others. If you give me an aversion to lying then I have a reason to tell the truth, and if you give me a desire to help others then you have given me a reason to be charitable.
However, you cannot change a person's desires by reasoning with him. Persuading a person to adopt an aversion to lying or a love of freedom by reasoning with him is no different than persuading a person to love the taste of broccoli or to hate chocolate cake by reasoning with them. You can persuade them that broccoli is good for them and chocolate cake is not, but this is not the same as persuading them to like broccoli and to hate chocolate cake.
The tools for "giving people reasons" in this sense are praise and condemnation. They also include reward and punishment in the behavior modification sense – that which comes to be associated with something that is desired becomes, over time, to be desired for its own sake.
One of the drawbacks of this method is that it has no immediate effect. If somebody is intent on doing something evil (e.g., killing a hostage), then only the first two forms of persuasion are applicable in the short run. If none of them are useful, then evil will be done. Yet, it is still the case that what the agent does is evil if it is still the case that people generally have many and strong reasons to use type 3 reasoning to prevent people from killing hostages (or from taking hostages to begin with).
Even though moral persuasion does not involve reason, we can still use reason to decide the value of using these tools. The analogy that I have used in the past is that one cannot use reason to change a flat tire. Yet, there are objectively true and false claims that one can make about how to use the tools available to change a flat tire.
I have already gone overly long with this post so I will make one more quick statement and save the rest for later.
Moral statements are a combination of Level 1 persuasion and Level 3 persuasion. They are a type of Level 1 persuasion in that they say, "People generally have many and strong reasons to apply Level 3 persuasion to prevent people from performing that type of action." They are, themselves, a type of Level 3 persuasion because they are, in themselves, acts of praise and condemnation. Thus, they are (or can be) objectively true or false. At the same time, they contain an emotive component that is a part of their meaning that is functional (it aims to mold the desires of others through praise and condemnation) without being literally true or false.