A member of the studio audience has given me reason to go a little deeper into the nature of desire.
People are not actually moved by the desire to maximize the harmonicity of desires. They have more specific and diverse desires.
This is true, and this is exactly what desire fulfillment theory claims.
Consider a being that has a desire that A, and a stronger desire that B.
Such a being would prefer a state of affairs in which both A and B are true. If this option is not available, the next best thing is a state in which B is true. Failing that, the being would settle for a state in which A is true. The being would be indifferent to a state in which neither are true.
(Note: An aversion is a negative desire, not the absence of a desire. This agent is not averse to the state in which neither A nor B is true. The agent simply sees no value in a state. An aversion is a negative desire (a desire that not-A. It is not the absence of desire (a not desires that A.)
I do not need to postulate – in fact, it would be foolish to postulate, a third desire – a 'desire to maximize the harmonicity of desires.' What would this give me? Now, we would have three desires – a desire that A, a desire that B, and this desire that C where C = "the maximization of the harmonicity of desires". This does not answer any questions, because we still need to figure out how this desire that C fits with the original desires.
Think of a hot air ballon being launched. It has a force causing it to go up. It has another force (wind) causing it to move to the east. The result is that it will move up and to the east. We do not need to postulate a principle of physics that says that things should ‘maximize the harmonicity of the forces acting upon it.’ All we need are the two forces themselves. They will do all the work.
The presence of a desire that A motivating the agent to realize states of affairs in which A is true, and a desire that B motivating the agent to realize states of affairs in which B is true, is sufficient. The agent then has sufficient reason to act so as to realize a state of affairs in which both A and B are true.
Now, let us introduce a second person into this system. Furthermore, we give our agent the option of choosing to give this second person a desire that D, or a desire that E. A desire that D will motivate our new agent to act in ways that will bring about a state in which A and B are both true. A desire that E will bring about a state in which neither is true (or only one is true).
Clearly, our agent has reason to act to give this new agent a desire that D.
Again, I do not need to postulate any type of desire to maximize the harmonicity of desires. I do not even need to postulate altruism or empathy. I need nothing but the desire that A and the desire that B.
Again, I do not need to add anything else to the mix. The fact that the agent has a desire that A and desire that B is sufficient to give him a reason to choose harmonious desires for other agents.
[T]he idea that all desires should be fulfilled equally ignores their separate nature (so that one sense can overcome the other), the existence of other intuitive desires.
There is no idea that all desires should be fulfilled equally. There is only the desires themselves motivating agents to act so as to realize states of affairs in which the propositions that are the objects of their desires are true.
Our agent, in the case above, does not need an idea that his desire that A should be fulfilled equally with his desire that A. He simply has a desire motivating him to realize a state of affairs in which A is true (that fulfills desire A), and a desire that B motivating him to realize a state of affairs in which is true (that fulfills desire that B). This agent is motivated to choose a state in which both A and B are true above all others.
And this agent, having the motivation to realize states of affairs in which A and B are true, has otive to cause others to have desires compatible with realizing those states of affairs.
An idea that all desires should be fulfilled equally does no work. It serves no purpose, and can be discarded. So, it is no objection to this theory that I cannot defend such a thesis.