On Desire 2018. Part 27: Having a Fit

Beliefs are supposed to conform to the world, whereas the world is supposed to conform to our desires.

Lauria, Frederico, (2017), “Guise of the Ought-to-Be” In Deonna J. & Lauria F. (eds). The Nature of Desire. Oxford University Press.

This is an oft-repeated slogan identifying the key difference between desires and beliefs. If Agent believes that P, and P is false, then Agent is supposed to change his beliefs - believe that not-P. In this way, beliefs are supposed to conform to the world. But if Agent desires that P, and P is false, P needs to do something to make P true. If your theory of desires cannot handle this fact, then you need to rethink your theory of desires.

I want to throw an idea out there and see if it survives.

I have been defending a theory of desire that says that a desire is an assignment of a value of importance to a proposition being true. This is a rather new formulation - I have not used it in my discussions of value until recently - until I started looking at theories of desire in detail.

When this originally came to me, I thought of it as, "A desire is an assignment of value to a proposition being true." However, I immediately realized that the phrase, "assignment of a value to a proposition being true" is ambiguous. It could mean what I wanted it to mean. On that definition, it tells us how badly the agent wants it to be the case that the proposition is made or remains true. However, it could have another meaning. It could tell us how confident the agent is in whether the proposition is true. This is a proposition that epistemologists call "credence".

So . . . in discussing the direction of fit of desires and beliefs, perhaps desires and beliefs are more alike than we have been thinking.

Both desires and beliefs involve the assignment of a value to a proposition P being true.

A belief assigns a credence value to the proposition P being true - a measure of how confident the agent is in whether P is, in fact true.

A desire assigns an importance value to a proposition P being true - a measure of how strongly motivated the agent is in making it the case or keeping it the case that P is true.

This, it seems, fits the "direction of fit" metaphor like a metaphorical hand in a glove. It is almost a restatement of the principle that if the belief does not conform to the world, then change the belief. However, if the desire does not conform to the world, then find some way to change to the world.

I have not had the time I need to really work out if this thesis is correct. However, since Lauria has presented the direction of fit principle as one of three desiderata that a theory of desire must meet, I sought to use the opportunity to at least put this idea out in the world. It may be of interest to somebody.

Another thesis that Lauria says a good theory of desire must meet is the "death of desire" principle. I have mentioned this principle a couple of times in this series - once (see The Death of the Death of Desire Principle") in some detail. I think I have a couple more nails to drive into this particular coffin (or another stick to use in beating this dead horse), which I will discuss next time.