Is and Ought Revisited

A useful Facebook discussion . . .

Yes, such creatures apparently do exist. Don't interrupt.

A useful Facebook discussion has given me to revisit the derivation of 'ought' from 'is' and examine some of its elements with a bit more care.

Here is the standard derivation that I have given to a hypothetical 'ought'.

P1: Agent desires that P
P2: Doing A will realize P
C: Therefore, Agent ought to do A.

Now, in order to make this into a valid argument, we need to specify some of the details.

First, let us examine the premise: Agent desires that P

Agent desires that P

Agent desire that P implies that Agent has a motivating reason to realize states of affairs in which P is true. This is what it means to have a desire. Desires provide motives to act. An aversion is a desire that not-P, so aversions also provide reasons to act - reasons to prevent the realization of states of affairs in which P is true.

Doing A will realize P

The Facebook discussion made me realize that I was hiding an implicit assumption in this. In order for this inference to work out, we must define realize in this context to mean that doing A will realize a state of affairs in which P is true, and not doing A will prevent the realization of states of affairs in which P is true.

You see, if we stick with a concept of realize where it simply means creating a state of affairs in which P is true then there will be cases when the premises are both true and the conclusion is false. These are cases where doing A will realize a state of affairs in which P is true, but not doing A will also realize a state of affairs in which P is true. That is to say, P will be made or kept true no matter what I did. I desire that the sun will come up in the morning . . . this is true. It is also true that, if I do a chicken dance, the sun will come up in the morning. It does not follow from this that I ought to do a chicken dance because it is also true that if I do not do a chicken dance, the sun will come up in the morning.

So, lesson learned: We must understand doing A will realize P to mean that doing A will bring about a state of affairs in which P is true and not doing A will bring about a state of affairs in which P is false. Now the agent has a reason to do A.

Therefore, Agent ought to do A

This part has always been something that I needed to be clear about.

The sense of ought that I talk about here is prima facie ought. It is a sense of ought that means nothing more than has a prima facie reason to do A. This is a reason that can be outweighed by other reasons that the agent has. It is a kind of reason that should be outweighed by other reasons that the agent should have. It is not a moral ought. It is not an all-things-considered ought.

Here is a same argument presented in this discussion - modified somewhat to eliminate some confusing elements.

P1. (premise) You have a desire to have money.
P2. (premise) Taking your friend's money will satisfy that desire.
C. (conclusion) Therefore, you ought to take your friend's money

Now, of course this argument is not valid if we take the 'ought' in the conclusion to be a moral ought or an all-things-considered ought.

In the case of the all-things-considered ought the argument only considers one thing, not all things.

In the case of moral ought, I have argued elsewhere that moral ought is not grounded on the desires the agent has. It is ground on the desires that people generally have reason to promote universally. So, these premises do not justify a moral-ought conclusion.

I can illustrate the prima facie reason easily enough by imagining that the money turned up missing. Now, as the crime investigation team, we need to determine who took it. We ask, "Who has a motive?"

Well, in fact, everybody has a motive to take the money in that everybody has at least one desire that can be better fulfilled by taking the money. Our list of suspects starts off being quite large - and it is large precisely because the argument above is valid for everybody. The conclusion is true in the sense that . . . yeah, you have a reason to take your friend's money. But, this is not an all-things-considered ought which would also consider your aversion to harming your friend or with damaging your friendship. Nor is it a moral ought that considers the fact that people generally have many and strong reasons to promote universally an aversion to taking the property of others.

With these elements in place, we can see how we can derive an ought from an is. From this foundation, we can build more complex oughts, such as practical oughts and moral oughts.