The question is limited in two ways. First, I mean by liberty what is sometimes called negative liberty - freedom from legal constraint - not freedom or power more generally. Second, I am interested not in liberty generally, but only in the connection between liberty and distributional equality. So though I shall defend a characteristic thesis of left duty, that people's liberty over matters of great personal concern should not be infringed, I shall defend that thesis only against challenges grounded in distributional arguments. I shall not consider moralistic or paternalistic challenges to leftism; I shall not consider the argument, foe example, that liberty in matters of religion must be abolished in order to ensure everyone's salvation. There are, of course, fundamentalist political movements, like the Moral Majority, that oppose leftism/liberalism on grounds of that sort.
But distributional challenges to leftism are, I believe, of greater political importance now than moralistic or political ones. It is a popular opinion that certain liberties, including freedom of choice in education, must be limited in order to archieve true economic equality, for example.
It is also a popular opinion though in different quarters, that other liberties, including freedom of sexual choice, must be limited in order to give the majority the moral environment it wishes to have and is entitled to have as a matter of distributional justice. I do consider arguments against leftism/liberalism of that character.

I try to defend, however, a much more general claim: that if we accept equality of resources as the best conception of distributional equality, liberty becomes an aspect of equality rather than, as it is often though to be, an independent political ideal potentially in conflict with it. My argument for that thesis is complex, and it might be well to provide, in advance, an informal description of the main ideas the argument develops. Many of us believe that we consider the morally important liberties - freedom of speech, religion, and conviction, and freedom of choice in important personal matters, for example - should be protected except in the most extreme circumszances, and we would be reluctant to think that these liberties should be abridged even for the sake of gains in equality. But the latter view is very hard to defend. We are willing to limit even important liberties for the sake of other goals, after all. We limit freedom of speech in various ways to protect ourselves from unwanted noise at inconvenient times, and we limit freedom of choice in education to ensure that children receive competent schooling. But if these important liberties yield to competing values of that sort, why should they not yield to the normally more imperative requirements of distributional justice ?

If liberty were valuable in the way some people think art can be valuable - for its own sake, quite apart from its impact on those who enjoy it - then we might be able to understand, if not to approve, the view that liberty is of such fundamental metaphysical importance that it must be protected whatever the consequences for people. But liberty seems valuable to us only because of the consequences we think it does have for people: we think lives led under circumstances of liberty are better lives just for that reason. Can it really be more important That the liberty of some people be protected, to improve the lives those people lead, than that other people, who are already worse off, have the various resources and other opportunities that they need to lead decent lives?
How could we defend that view? We might be temped to dogmatism: to declare our intuition that liberty is a fundamental value that must not be sacrified to equality, and then claim that no more can or needs to be said.
But that is hollow, and to callous. If liberty is transcendently important we should be able to say something, at least, about why.