Many political philosophers overestimate the importance of abstract principles for the design of institutions. Most issues of the day cannot be resolved by a sole appeal to basic principles. Whether we talk about healthcare, the economy, poverty alleviation, crime control, and even foreign policy, philosophical principles at best underdetermine results, and at worst are irrelevant. Yet many philosophers think that if they can just make the right conceptual distinctions and identify the right political principles they can select the best institutions, laws, and policies. Not so. Abstract moral principles are insufficient to explain the differences between good and bad laws. An adequate theory requires an appeal to consequences in terms of human welfare.  A couple of examples will show what I mean. From Rawls’s difference principle (institutions should be arranged for the benefit of the worst-off) it does not follow that the state should force transfer payments to the poor:  if a free market improves the poor as a class, then the free market is superior to transfer payments. From Ronald Dworkin’s principle of equal concern and respect it does not follow that we should have government-run universal healthcare:  if a different system better realizes equal concern and respect, then that system would be superior. Yet many philosophers illegitimately jump from abstract principles to concrete institutional proposals. I think the reason for this fallacy is the anti-utilitarian bias of modern political philosophy. It is one thing to claim, plausibly, that maximizing aggregate welfare cannot be a paramount goal. It is a very different thing to claim, implausibly, that nonconsequentialist principles alone provide the answer to social and political problems. To be sure, abstract principles provide some important answers. For example, abstract principles alone tell us that torture is wrong, or that the government should not censor the press or kill people without due process of law. But most social issues are not like that. They require a careful calibration of competing interests and goals. In particular, they require accepting the kinds of trade-offs that abstract principles usually do not tolerate well. Suppose the government believes that everyone has a right to food and shelter, but it cannot provide both at the same time to everyone. The government perforce denies shelter to some in order to feed others. The proclamation of the right to shelter is empty; there is no right to shelter. Rather, the government addresses the incidents of poverty by making trade-offs between the various competing needs of the poor.

Such disdain for the utility principle leads many philosophers to a general disdain for things empirical. They get bored with economics, political science, and empirical studies (part of the reason is that they are not particularly good at it.) For example, when discussing trade, some philosophers don’t want to hear about the law of comparative advantages. They think that the general principle that we owe a duty of solidarity to all fellow citizens settles the issue.  Related to this bias is the belief, held by influential philosophers, that the main problem in society is moral disagreement among the citizens (Rawls in Political Liberalism.) I think this is wrong: while of course there are genuine moral disagreements (abortion and euthanasia come to mind) most disagreements in society are empirical. I don’t know anyone who says that poverty is a good thing. Everyone believes that society must do something to alleviate poverty. The disagreement is about how to do this. Progressives think that coerced transfers are essential; classical liberals think that unhampered markets are better. To put the point in more technical terms:  a particular moral principle can only yield a concrete institutional proposal in conjunction with an empirical premise. If the empirical premise turns out to be false, so will be the proposal