This post is directed at those atheists (and others) who attempt to defend morality in terms of rational self-interest.
It is not that this is wrong, but that it confuses people.
There are two possible meanings of this phrase 'self-interest'.
One of the meanings works, and one does not work. Unfortunately, the meaning that does not work is the meaning that comes first to the mind of most who hear this term. Furthermore, many (most) of those who use this term equivocate between the two meanings themselves. So the listener, who calls to mind the meaning that does not work, is told half of the time that this is the correct meaning, and the other half that it is not.
So, we have confusion.
The two meanings are:
(a) "Interests in self"
(b) "Interests of self"
Of these two, the second is a much larger set. Some of a person's interests are interests in the self -- interests in having more money, in being happy, in having certain experiences.
However, there are many "interests of the self" that are NOT "interests in the self". A person may be interested in the happiness of the friend, or in the well-being of a complete stranger. He may be willing to sacrifice his life for the sake of a child, or a country, or a principle. Such a person is still acting on his interests. However, these are interests of the self that are NOT interests in the self.
As an aside, I would further assert that interests relate directly to desires. Desires are propositional attitudes -- a 'desire that P' for some proposition P is an interest in creating or preserving a state of affairs in which 'P' is true. There are no interests without desires, and desire sits at the root of all interests.
The concept of "desires of the self" or "interests of the self" refers to the desires that an agent has, regardless of what they are for. If he has a desire that Latin be preserved as a living language then he has an interest in creating or preserving a state of affairs in which Latin continues to be a living language. Speaking in terms of propositional attitudes, the concept of "desires of the self" places no limit on the proposition 'P' that may serve as the object of a 'desire that P'.
The concept of "interests in the self," however, does place a limit on the set of propositions P that may serve as the object of a "desire that P." It states that those propositions P must contain a first-person indexical (they refer back to the self that is speaking), and seeks the 'benefit' of that person.
Clearly, the set of all propositions is larger then the set of propositions containing a first-person indexical and referring to the benefit of that person. That is to say, the set of 'interests of the self' is potentially much larger than the set of 'interests in the self.'
In addition, those who speak in terms of 'interests in the self' have another problem: they need to provide us with a meaningful account of the concept of a 'benefit'. What makes a particular state count as a 'benefit', and another state count as a 'harm'? This question must be answered if we are going to make sense of the phrase 'interests in the self' in terms of self-benefit.
Now that we have distinguished the two concepts, we can see where the confusion comes from when people use the phrase 'rational self-interest.'
I am going to assert that most people who hear or read the phrase, 'rational self-interest' immediately call to mind the narrower 'interests in the self' definition. To make matters worse, the 'rational self-interest' theorist often asserts this same definition. Then the listener/reader starts to raise all sorts of objections to this 'interests in the self' concept. In responding to this, the 'rational self-interest' theorist equivocates. He switches to the concept of 'interests of the self' to defend himself from objections to the 'interests in the self' concept, claiming that this is what he meant all along. Yet, when asked for a specific definition, the defender of rational self-interest goes right back to using the 'interests in the self' definition.
After which, the listener walks away mumbling to himself, 'those guys are nuts.'
I hold that the meaning of a phrase is determined by what it calls up in the mind of its expected audience. A person who uses a term in a way that is not standard for that audience needs to specify that definition. 'Rational self-interest' used when addressing average readers calls to mind 'interests in the self.' If the speaker does not intend to use that definition, he should specify the definition he does intend to use.
Rational Interests Of The Self
If you read about somebody talking about the relationship between morality and ‘rational self-interest’, see if you can determine whether the author is talking about ‘interests in self’ or ‘interests of self’ – and even whether he recognizes the distinction.
If he is using the concept of ‘interest in self,’ recognize that a great many reasons for action exist and have just as much influence on human action – just as much importance to the people who have those reasons – that are not being considered in his philosophy.
And if he is using the concept of ‘interests of self’, see if you think his use of the term ‘self-interest’ in this sense confuses or clarifies the issue.