Here is a thought experiment.  It’s intended especially for libertarians, and even more so for natural rights libertarians of the Lockean/Nozickian/Rothbardian sort.  But the rest of you should feel free to play along at home.

Suppose a genie gives you the power to snap your fingers and instantly implement your preferred theory of political justice. 

-          By “theory of political justice” I mean, very roughly, your theory about the basic moral constraints that govern what states (or, if you prefer, the “basic structure of society”) ought to do or refrain from doing – whether and to what extent taxation is permissible, whether some form of social safety net is mandatory, whether the government can prohibit or regulate food and drugs, and so on. 

-          By “implement” I mean that the relevant agents of the government (or other institutions within the basic structure) will make reasonable efforts to put your theory into practice.  Human nature will not change, and so we can still expect some “normal” amount of corruption, disobedience, and so on.

You, of course, believe that your theory of justice is correct.  You also believe (correctly) that most other people do not. 

Does the fact that others disagree give you any moral reason not to use the power you’ve been given – beyond reasons of a merely pragmatic sort?

One way of thinking about this question is to see it as a question about legitimacy, not justice.  Up until relatively recently, it was common for political philosophers not to draw a distinction between these concepts.  John Rawls’ 1971 book, A Theory of Justice, for instance, was simply about justice: about the moral principles that he thought should govern the basic structure of society.  After writing that book, however, Rawls realized that … surprise!  Not everyone agreed with him.  Other people had their own theories of justice, and not simply because they were stupid or malicious.  Justice, it seems, is something about which reasonable people can disagree, and will likely to continue to disagree for the foreseeable future.

And that gives rise to the problem of legitimacy: how can any particular principles of justice be imposed on citizens who reasonably believe those principles to be incorrect?  The answer to this question was the subject of Rawls’ 1993 book, Political Liberalism.  Rawls’ argument in this book is far too sophisticated and complex to accurately convey in a short blog post.  See here for a very good summary.  But the essence of his solution to the problem of political legitimacy was that political power could be legitimate by being based on what he called a political conception of justice.  And what makes a conception of justice political is that it is based, not on any particular philosophical theory about the nature of justice or the good life, but on the ideas common to a society’s public political culture – ideas that different persons with their different philosophical and religious worldviews could converge in endorsing.

There’s a lot more to say about Rawls’ approach to the issue of legitimacy, of course.  But rather than diving into that here, I just want to draw a few connections and pose some questions for us to think about.

First, taking the issue of legitimacy seriously gives us another very important reason to look for what Danny earlier described as overlapping consensus arguments.  Those arguments are nice not just because they give us a rhetorical tool to persuade people who do not share our fundamental moral commitments.  They are arguably necessary if we seek to establish the moral legitimacy of our proposals in a world of reasonable evaluative diversity.

Second, an obvious worry about Rawls’ strategy is that, given the extreme diversity of people’s worldviews and theories of justice, we will not be able to find any principles on which we can all converge.  Rawls tries to avoid this problem by insisting that we need only consider those views that are “reasonable.”  But the meaning of this term is notoriously unclear, and we might very well worry that Rawls achieves what consensus he does only by ruling out far too many competing views as “unreasonable.”  Interested readers should look at the work of Gerald Gaus, especially his newest opus, The Order of Public Reason.  Gaus shares many of Rawls’ views about reasonable evaluative diversity and public justification, but is concerned that Rawls fails to take real-world diversity seriously enough.  If he were to do so, Gaus argues, many fewer policies would pass the justificatory hurdle and the resulting state would look much more like a classical liberal one than anything Rawls ever envisioned.  (For shorter bite-sized presentations of this view, take a look at this paper or this one.)

Third, it’s worth thinking about the extent to which this might be a special problem for libertarians.  Libertarianism, as Loren Lomasky noted in his “Libertarianism as if (the Other 99% of) People Mattered,” is a view that makes very strong claims that most people think are flat-out wrong.  If this is true, what relevance does it have?  Does it show that libertarianism is unsuitable as a public morality? Isn’t there something anti-individualistic about imposing libertarian institutions by force on a population that reasonably believes them to be profoundly immoral?

Finally, might it be an even more pressing problem for bleeding heart libertarians?  If legitimacy requires justifying policies to everyone, including the poor, might this affect the kind of libertarianism that can be justified?  Might the only kind of libertarianism that can be universally justified be one that includes some form of government provided safety net?  Perhaps it’s no coincidence that the two libertarians who are most notable for pursuing this kind of approach – Loren Lomasky (in his Persons, Rights, and the Moral Community) and Gerald Gaus (in the works referred to above) endorse such a deviation from strict laissez faire?