Plenty of political theories can capture the complexities of political debate, even if many do not. But utilitarianism, almost of necessity, must take account of the complexity because of its underlying value theory. One particular problem with some approaches to liberalism (or political philosophy more generally) is that although the theorist may want to recognize a variety of values, it can be difficult to justify why those values matter. Consider, for instance, the fundamental liberal commitment to persons as “free and equal”. What are the grounds for asserting that persons are free and equal? How could we convince someone to care about such values, if they do not already?
One common approach is to appeal to “natural rights”, but that only pushes the question back further: what is the source of such natural rights? How would you convince someone who doesn’t buy into natural rights (or those particular natural rights) that we do, indeed, have them, and that your list of natural rights and your conception of those rights is the correct one? John Locke had a pretty good answer: we are all equally the property of God and equally made in its image. This is a good answer, as far as it goes, but of course is not particularly helpful in a sufficiently (religiously) diverse society.
Now I don’t mean to say there aren’t other good approaches here. But, I just use this example to motivate what I find particularly powerful about the story the utilitarian liberal can tell. If we take as our starting point the maximization of welfare, and understand welfare in a subjective way (whether this be about ‘happiness’, desire satisfaction, preference satisfaction, or whatever) then our derivation of the political values of freedom and equality (and others) comes from two sources: individuals care about these things and we know that societies which respect/protect/promote these sorts of values better promote welfare than societies that do not. In classic Millian form, the story is simple: It’s good for me and it’s good for us.
But then notice, too, that deriving political values in this way also helps us think through how best to conceptualize the values. There are many different conceptions of individual liberty (and social equality, and community, etc.). Many political philosophers go to great pains to offer a priori justifications for their conceptions. But this is not the utilitarian way. Instead, we do precisely what Mill and the pragmatists would advocate: We derive our conception from intersubjective understanding, suitably integrated with empirical study. So, for instance, we may find that many people particularly hate there being explicit impediments to their pursuit of their goals. This helps us see that our conception of liberty should certainly incorporate a negative component: whatever else liberty involves, it involves the absence of impediments to peoples’ ability to achieve their goals.
But, both for social reasons and for psychological reasons, I don’t think this can be the full story of liberty. There must be some positive element. For it is not just explicit impediments that can get in the way of fulfilling one’s goals. If one has no means to pursue or achieve one’s ends, then that is also taken as a significant infringement on one’s freedom. Moreover, various empirical and historical work has shown that societies which organize around a purely negative conception of liberty, and provide nothing in terms of support for effective agency, do worse than ones that support all people with at least the basic minimum to pursue their ends. And so, once again: a minimally positive conception of individual liberty (something like the effective agency view Gaus also defends as a ‘shared conception of liberty’) is good for me and it is good for us.
Thus, utilitarian liberalism has an in-built method of reviewing and revising our understanding of central political values by reference to both empirical data and sensitivity to changing social expectations. As Mill puts it in Utilitarianism, we have the whole history of human existence to tell us what tends to conduce to human happiness and what tends to frustrate it. And that history is regularly updated and so should be our understanding of what conduces and frustrates human happiness, as partly represented in our conceptions of the core political values.