Michael Smith: Desires Constituative of Rationality

(1) There are desires constitutive of being rational.

(2) If there were a desire constitutive of being rational, then it would answer Mackie's objection that there are no objective values without postulating non-natural properties.

I am going to have to be careful here.

I hold that the first proposition is false.

Michael Smith wants to suggest that the second proposition could be true. (Smith, Michael, "Beyond the Error Theory," in A World Without Values: Essays on John Mackie's Moral Error Theory, (Richard Joyce and Simon Kirchin, eds.), 2010.)

I need to be careful to prevent my beliefs that the first proposition is false from contaminating Smith's argument that the second proposition could be true.

However, I find this difficult.

Consider the following two claims:

(1) Fully grown horses can fly.

(2) If fully grown horses could fly, then granite would sink in water.

I take the first statement to be false.

Now, when I go to the second statement, I am confronted with the question, "How was reality changed so as to make it possible that fully grown horses can fly?"

It is only after I know what those changes are that I can then infer what those changes imply about whether granite would sink in water.

Consequently, to assess Michael Smith's claim that if desires are constituative of rationality then this would handle Mackie's error theory, , I have to consider the changes to the real world that would be required to make it the case that desires are constituative of rationality. Only then will be able to infer from those changes whither this they would answer Mackie's challenge that there are (or can be) no objective values.

More specifically, Smith wants to examine the suggestion that a statement of the form, "People intrinsically desire that P" is constituative of rationality.

I take Smith's claim of "intrinsic rationality" to be the same as what I call "desires as an end". If we accept this substitution, then I certainly have to accept that, for each has a number of intrinsic desires. There is no question here.

An obvious example is that many people have an "intrinsic aversion" to their own pain. That is to say, they see the avoidance of their own pain as an end and will choose to avoid pain even in circumstances where the agent will otherwise benefit. Offer somebody a dollar if he would endure 1 hour of painful torture, and I suspect there would be few takers.

So, the problem is not with the claim that "people intrinsically desire that P". The problem is with the claim that "people intrinsically desire that P" can be constituative of rationality.

Intrinsic desires are like eye color, opposable thumbs, being bipedal, having a spleen, and having the capacity to see color. We have acquired these through a long history of evolution. Having an aversion to pain is no more constituative of rationality than having a spleen, or having blue eyes.

Our brain is plastic - so that our desires are, in part, shaped by our experiences and not just our genes. However, the number of fingers (or even the number of arms and legs) a person has is also shaped by experience. The ability to see and to hear, and the color of one's eyes and hair, can be altered through interaction with the environment. Interactions with the environment can change the fact of whether a person has a spleen or an appendix. However, this fact does not make it the case that any of these states are constituative of rationality.

Similarly, the fact that experience can alter a person's desires does not make the desires constituative of rationality.

It may be irrational to cut off one's arm, and it may be irrational to choose to acquire an addiction to tobacco (by taking up smoking), but this does not imply that having an arm or not having an addiction to tobacco is constituative of rationality. The reason that the actions can be considered rational or irrational is because intentional actions are grounded, in part, on beliefs, and those beliefs can be checked for rationality.

Now, I can turn to the problem I have with Smith's thesis that IF desires were constituative of rationality, then we may have an answer to Mackie's objection to the existence of objective values. However, this is like saying IF having an appendix were constituative of rationality or IF eye color was constituative of rationality or IF having opposable thumbs were constituative of rationality. I can't make enough sense out of the antecedent to answer the question.

There is no desire constituative of rationality. It may still be the case that if there were desires constituative of rationality that Mackie would have a problem dealing with them. However, that issue becomes a moot point in the shadow of the fact that there are no desires constituative of rationality.