When he was about to receive the Nobel Prize in economic science, I interviewed F. A. Hayek for Reason magazine (at his home in Salzburg, Austria). Although he didn't believe that political economists should dwell on ethical issues per se, he was by no means "necessarily a moral relativist" as Francis Fukuyama asserts in his Sunday New York Times Book Review piece (5-8-2011) of the new edition of The Constitution of Liberty (edited by Ronald Hamowy for the University of Chicago Press, 2011).
Hayek did, of course, object to the notion, mentioned by Fukuyama, that "there is a higher perspective from which one person can dictate another's ends." However, the stress here needs to be on "dictate." No one can do what is morally right when this is being dictated to or coerced from a person. That isn't at all because ethics or morality is subjective or relative. It is because to hold someone responsible for either morally right and wrong actions, it is that person who has to be the cause of it. The criminal law recognizes this, as have most moral philosophers. And when it is denied that one has free will or can exercise free choice about what one will or will not do, morality disappears. This is why so many thinkers who embrace determinism either reject morality as bogus or transform it into a social psychological device by which desired behavior might be encouraged or prompted from people. (A good example is much of the current work by nureoscientists!)
As Hayek put it elsewhere, "It is only where the individual has choice, and its inherent responsibility, that he has occasion to affirm existing values, to contribute to their further growth, and to earn moral merit." ("The Moral Element in Free Enterprise," Studies in Philosophy, Politics and Economics [New York: Simon & Schuster, 1967], pp. 230.) However, this view does not depend on moral relativism but on the ancient idea, held by most moral philosophers, that for conduct to be morally significant, it must be done freely, as a matter of the free choice of the moral agent.
One way to discredit defenders of political and economic liberty is to allege that they do not take ethics or morality seriously, that they are indeed subjectivists or relativists. Most people are pretty sure that some human conduct is ethically wrong or right. They teach this to their children and hold to this idea as they judge their fellows, including politicians and international movers and shakers. So to suggest that someone like Hayek, who defends freedom of choice in the market place, is a moral relativist pretty much serves to dismiss his or her views. But it is a mistake.
Alas, the effort does not succeed even when it is made by a famous public intellectual like Francis Fukuyama. It would have been far more accurate to say that for Hayek the tenets of a sound ethics or morality aren't directly relevant to political economy. As he said in the same interview for Reason magazine, "I don't see why it should be necessary for political philosophy to have any view at all about what is right for man – unless the political system does something about it, it needn't concern itself with what is right for man." This may be objected to for a variety of reasons but not because it supports moral relativism. Indeed, something akin to this position is held by Professors Douglas Den Uyl and Douglas Rasmussen in their book Norms of Liberty (Penn State Press, 2005) when they argue that the principles of classical liberalism aren't directly derivable from ethics but are, instead, meta-norms, meaning, norms that are required for the social realization of ethically significant conduct.
The relationship between objective personal morality and the principles of politics which are basic to a constitution such as Hayek's constitution of liberty is a challenging aspect of political philosophy. It does not help to casually dismiss Hayek's approach by caricaturing it as moral relativism.