In an earlier post, I gave the following generic definition of social justice:

Social justice is a moral standard by which some people judge political and economic institutions. Advocates of social justice believe the moral justification of our institutions depends on how well these institutions serve the interests of the poor and least advantaged. The basic institutions of society must sufficiently benefit all, including the least advantaged and most vulnerable members of society.

I doubt we can define the term “social justice” precisely, by necessary and sufficient conditions. Almost no words in the English language can be defined so precisely. Instead, the definition above captures in a broad way what people have in mind when they discuss social justice. There are various possible conceptions of social justice. This definition characterizes most of them. It does so without being empty. Murray Rothbard doesn’t have any concern for social justice, so defined, as far as I can tell.

Note that I am not trying to tell you what I think the true principle of social justice is or how it fits into the correct theory of justice. I am trying instead trying to describe what different theories of social justice have in common. All theorists who advocate social justice believe something like this:

• If under favorable conditions, an political-economic regime systematically causes many innocent people, through no fault of their own, to live in poverty, without much opportunity, and without much ability to enjoy their freedom, and if there is some alternative regime that, under those same conditions, would eliminate these problems, this provides a strong presumption in favor of that alternative regime.
• If our basic institutions systematically fail to benefit innocent people, or systematically tend to harm them, then it is unreasonable to ask them to observe those institutions. For instance, if through no fault of my own, some property rights regime causes me to starve, and if this isn’t just a result of bad luck but is a systematic effect of that regime, then the rest of you can’t demand I play along with the regime.

David Friedman and Bryan Caplan both worry that this is all too inexact. People who advocate social justice believe the justification of our institutions depends upon those institutions ability to serve the interests of the poor and least advantaged. But just how strong is this dependency relation? Do utilitarians qualify as having concern for social justice, since utilitarians counts the interests of the poor?

Any particular theory of social justice might give an exact answer. But I am here trying to talk about what the different theories of social justice have in common, and so I cannot give an exact answer. Or, rather, if I give an exact answer, it will be artificial. I’ll exclude some theories that others reasonably think should be included and/or include some theories that others reasonably think should be excluded.

There are clear cases where someone’s commitment to the poor is too weak for him to count as advocating social justice. There are clear cases where the commitment is strong enough to count as a commitment to social justice. And then there are in-between cases where’s it’s not clear. No big deal–most of our language works this way.

The crudest forms of utilitarianism won’t qualify as having a real concern for social justice, because they don’t give the interests of the poor (or any individuals’ interests) the right kind of consideration. Utilitarianism attaches no intrinsic importance to the distribution of utility. Imagine the following situation:

Malevolent Utility Monsters: Suppose the top 1% of people are malevolent utility monsters, with a nearly unlimited ability to feel enjoyment/pleasure/happiness. Suppose these utility monsters enjoy watching other people suffer. If they see or know that a person suffers from X disutility, this causes them to experience X^2 utility. Now, suppose there is an economic system Y that causes the bottom 99% to starve. Suppose that as a result Y causes more overall utility than any other economic system.

If the crudest forms of utilitarianism were true, then we would be morally obligated to instantiate economy system Y under those specified conditions. It would be silly to say that these forms of utilitarianism show a concern for social justice–they “count” the interests of the worst off, but they allow the poor to be exploited and tortured in order to benefit others. That has to be too weak of a dependency relation.

Utilitarianism tells us to treat the poor as potential containers for utility, and it requires us to treat them as mere instruments for producing utility in others if doing so would maximize utility. Crude utilitarianism is too weakly committed to helping the poor to count as a concern for social justice.