Motivation vs Evaluative Theories of Desire

I am starting a book on the nature of desire.

It begins by presenting two conceptions of desire.

One is the view that desire is a motivational state - a disposition to (and reason to) act so as to realize that which is desired.

The competing view sees desire as an evaluative state - a disposition to see something as good.

In addition to aiming toward satisfaction in the way explained, desires are often said to aim at the good, just as beliefs aim at the truth. One way of understanding this slogan is to interpret it as follows: one cannot desire something without “seeing” some good in it. Call this the “guise of the good” thesis.

Now, I have attached the term “good” to “that which will fulfill the desires in question.” However, one must be careful about the direction of fir here. Is something good because it is desired? Or is it desired because it is good?

To answer this question, I think that all we need to do is to look at the desires of animals - a dog’s aversion to pain. Does it make sense to think that Fluffy, who broke a leg due to getting it caught as she fell off the cabinet, perceives the pain as bad? I find it difficult to even think of Fido as judging this dog food better than that, or the ram in the forest judging the doe as attractive. Desires and aversions are much simpler than this. They are mental states motivating the agent to realize certain states of affairs.

When humans started to acquire intelligence, discovering that they favored some states over others - preferred the taste of some food, preferred to be warm on a cold winter night, wanted food and sex, it is not unreasonable to think the the goodness was in the thing wanted and not merely a motivation to realize some state. It is as natural as thinking that the Earth is the center of the universe. However, if we think about it a bit, we can see that this is not the case. The bird with a disposition to sit on its eggs to keep them warm is not "aiming at the good". She is simply doing what she likes, and has evolved to like to sit on her eggs to keep them warm. Ancestors who evolved this disposition had more eggs survive to become birds which became this specimen's ancestors.

So, things are good because they are such as to fulfill the desires in question. And malleable desires are good to the degree that they tend to fulfill the desires in question. That fits the relationship between desire and goodness better than the evaluate state theory.