John Maynard Keynes once observed that the â??ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly believed. Indeed, the world is ruled by little elseâ?¦. Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back.â? People seldom know where those ideas have come from, however, to the chagrin of professional philosophers. Polls regularly show that a significant percentage of Americans believe that “From each according to his ability, to each acording to his needs,” is in the Declaration of Independence or the Constitution.

John Rawls, the grand don of modern political philosophy who died last month, did live long enough to see his central ideas percolate into the broader culture. But as is inevitably the case when a rich and complex philosophical theory noted for its rigor is translated into sound-bite-sized bits for popular consumption, quite a bit is lost in the process. Ripped from its context, Rawls’s most famous principle — which even in its orignal form would find few supporters among libertarians — seems to have found perverse applications that would horrify the great liberal thinker.

If you know exactly one thing about John Rawls, it’s probably his Difference Principle, the idea that inequalities between members of a society are only justified if they’re to the benefit of the worst off group. That is, people can be paid more as an incetive to produce more, but if after all that, a system of redistribution will, over the long term, tend to improve the condition of the worst off in society, then redistribution is required. This, he believed, was a rule of justice people would choose to organize a society from behind a “Veil of Ignorance,” where they didn’t know which particular place in the society they’d occupy. Hayek famously thought that Rawls was basically correct, and that laissez faire satisfied his criteria, but most — including most libertarians — have not.

Now, it would be surprising if this had been the only thing if Rawls said in a book as thick as his A Theory of Justice, and in fact, he said quite a lot more. The Difference Principle, also known as “maximin,” is the second of two Rawls says would be chosen from behind the Veil, and not the whole principle at that. His first principle, which takes priority over the second, is that the society is to enforce the most extensive (later revised to “a fully adequate”) set of mutually compatible “basic liberties,” which include classic liberal standbys like freedom of speech, of movement and association, of worship, and of personal bodily integrity. The first part of the second principle, also prior to the Difference Principle, insists that there be “fair equality of opportunity” in competition for jobs and other positions to which benefits are attached. And finally, the Difference Principle is only supposed to apply to certain “primary goods” — things like income and wealth, or the availability of healthcare and education — rather than any sort of inequality in how happy people are, or how well off they feel themselves to be on the whole. These nuances, alas, have not joined the Difference Princple in the popular consciousness so readily.

I mention all this by way of introduction, because it seems as though many people now apply the Difference Principle (whether or not they call it that, or have even heard of Rawls) much more broadly. If you suggest doing away with a centralized pay-as-you-go Social Security system already collapsing under its own weight, and allowing people to invest as they choose for their retirements, many will worry that some few will lose out on bad investments, even if they concede most would do better. If you suggest ending a catastrophic policy of drug prohibition, almost nobody worries that they will be seduced down a poppy-strewn path to hell, but quite a few will voice concern for those with less self control. Almost by definition, when people are able to choose to take a risk, some will be worse of for it: that’s what makes it a risk, rather than a guarantee. Some people are, at least in a narrow sense, better off for paternalism.

Obviously, though, it would be very much at variance with Rawls’s other liberal principles to curtail any freedom that might leave the worst off in a less attractive position But as Rawls’s great intellectual opponent, Robert Nozick, pointed out, it is the paternalists, and not Rawls, who drew the right lesson from the framework of the Veil. If, in the end, people are chosing between static states of affairs, between roles in life that they happen to occupy, why would they give freedom the special priority Rawls assigns it? Wouldn’t it be just one more good, like healthcare or income, to be weighed in with the rest, with any particular liberty valued only to the precise extent that it increased the probability of making the life one happened to occupy a happier one? Why not, then, curtail everyone’s liberty if the worst off — or at least the average person — is apt to make poor use of that freedom?

This seems (to me, anyway) as though it must be wrong, yet I don’t think it’s immediately obvious just why. When I struggle to put my finger on the problem, it seems that it is something like this: the choice situation of the Veil bleaches out an important part of what it is to be a moral agent, rather than just some locus of experience, to which things happen. From the outside perspective of an observer choosing between people to be, “what I do” is just an input into how I feel, and moreover, just a function of my arbitrary biology and the arbitrary things that happen to me from birth onwards. Yet from the inside, what I do — what I choose to do — is constitutive of who I am. Being just this person means making just these choices, pursuing just these ends. If that’s centrally important, though, then a framework for thinking about justice that privileges outcomes over process, that makes what I get rather than what I may do the key thing, is always going to miss the mark. That’s true whether we’re talking about Rawls’s system, one of the many flavors of utilitarianism, or indeed, any stricly consequentialist theory.

I’ve rehearsed these arguments, not for the sake of taking unanswerable potshots at a recently deceased man, but rather in honor of the late professor. Something I learned from Nozick, and an idea that’s influenced me strongly, is that a genuinely great philosopher is more illuminating, more interesting when she’s mistaken — and prepared to risk being mistaken — than even a pretty good one is when she’s right. Seeing where a deep theory falls apart reveals more than being satisfied with an easy certainty in a shallow one. So I’m grateful to Rawls, not just for what I think I’ve learned about political philosophy from his writing, but for this credo, or mantra, or little secular prayer: Let me often be wrong, but never complacent.