From Colin McGinn’s Moral Literacy (1992):
“Some readers may be wondering, sceptically, why they should bother to be virtuous at all. Why not be a bad person? What reason is there for being a good person? The answer is, there is no reason – or no reason that cuts deeper, or goes further, than the tautology ‘because goodness is good’. The reason you should be virtuous and not vicious is just that virtue is virtue and vice is vice. Ultimately, what you get from virtue is simply … virtue. Virtue may also get you health, wealth, and happiness, but there is certainly no guarantee of that – definitely not – and in any case that isn’t the reason you should be virtuous.” (p. 95)
Let’s dig a little deeper into McGinn’s reasoning:
“Moral justification, like all justification, comes to an end somewhere. At some point we have simply to repeat ourselves, possibly with a certain emphasis, or else just remain silent. Virtue is, if you like, its own justification, its own reason: you can’t dig deeper than that. To the question ‘Why should I care about others as well as myself?’ the best answer is another question: ‘Why should you care about yourself as well as others?’ In the case of the latter question, the right reply is, ‘Because you are a person to be taken into account too’; and in the former case, the right reply is, ‘Because they are persons to be taken into account too.'”
McGinn here ignores indexicality, as opposed to, say, how some Christian moral system might incorporate it. To the question ‘Why should I care about others as well as myself?’ that McGinn poses another answer is: you will be rewarded for your virtue (or punished for your vice), sooner or later. This is possible because moral guidelines in, say, such a Christian system are tied into a causal system that matters – i.e., the moral system is intended to be used, and so works with basic human psychology and action.
McGinn seems to pride himself on conjuring up a moral system that doesn’t matter, but this is a little too like the academics who pride themselves on useless research because it can accord higher status. It turns out that their research is useful in a sense (for their own status). Perhaps what McGinn is trying to do is develop a moral system which is practical, in that exercising or expounding it shows that one is higher status. “I don’t even need appeals to my own well being to motivate moral action!”, perhaps.
In this sense, McGinn’s moral system does have a reward (see here for a basic structure of moral systems): higher status is the practical, psychological justification for virtue in his system. To the extent a moral system like his will work, he needs something like this. The problem is that, as soon as people see the preening of a moral system like his for what it is, it starts to lose its higher status.