Is social justice an empirical characteristic of a set of social arrangements? And can social justice be a causal factor in processes of social change or social stability?
Before justice could be considered an empirical feature of a set of social arrangements, we would need to have a more specific understanding of what we mean by the term. And we would need to be able to "operationalize" this complex concept in order to be able to apply it to different social arrangements. But neither of these tasks is insurmountable; certainly not more so than defining and applying the ideas of fascism, liberal democracy, or welfare state to specific societies.
So let's begin with a simple, applicable definition of justice. Let's focus on just three dimensions of a society's functioning: distribution of access to society's wealth; the degree of abuse of power and its contrary, reliable legal protections of the person; and the extent of individual freedoms. Injustice involves --
- exploitation and inequality
- unwarranted coercion by the state or private organizations
- the abuse of people's freedoms.
But immediately a problem arises. Each of these features requires a key normative judgement. Exploitation is the unfair division of the fruits of productive activity among the participants. The qualifier "unwarranted" requires that we supply a normative theory of the state. And "abuse" of freedom isn't simply restriction on freedom; it is the unjustified or unequal restriction on freedom. So in order to measure any of these characteristics in a particular social context it isn't enough to know who gets what or who does what to whom; we need a background set of normative ideas that allow us to judge which kinds of treatment and inequality count as exploitation, coercion, or the abuse of freedom.
This is where Amartya Sen's ideas about capabilities, realizations, and freedoms are practical and useful. We might substitute "capabilities realization deficit" for exploitation. Here we might argue that a society that leaves a significant portion of its population in material conditions where they cannot fulfill most of their basic human capabilities is for that reason unjust. We might measure the gap in human development between the top quintile and the bottom quintile as an estimate of the degree of exploitation that is prevalent in a given society. We may not know in detail how the system of distribution works, but the severity of the gap gives reason to believe that a portion of the society is being treated unfairly. The Human Development Index provides a basis for beginning to assess different countries along these lines (link).
Second, we might measure coercion and legality by the estimating the degree to which a society has effectively implemented a working system of law that is applied equally. The World Bank has made some efforts in this direction through its Worldwide Governance Indicators (link; working paper here). This gives us an empirical measure of the degree of lawlessness and unchecked state power that exists in various societies.
We might measure freedoms by aggregating observable features of democratic participation in various societies. The Economist has constructed a Democracy Index that was first implemented in 2006 (link). This gives us an empirical way of assessing the rough degree of involvement citizens can have in public decision-making; or in other words, it is a measure of the degree to which it is possible for citizens to exercise their freedoms in a public space.
So we might imagine a "justice index" for a society that aggregates measures like these into an overall assessment of the degree of justice the society currently demonstrates. It would then be interesting to see how societies differ in this measure, and how other important social characteristics may be correlated with this measure. I haven't done this experiment, but here's what we might expect: higher injustice ratings correspond to greater likelihood of social conflict, lower productivity, and lower community and civic engagement.
What mechanisms might be hypothesized that would originate in these core aspects of a society's justice profile and its various outcomes? Here we can identify a couple of factors that would support a causal interpretation. For example, absolute or relative deprivation can cause people to rebel as they struggle to create social changes that protect their interests. Further, as Barrington Moore demonstrated in Injustice, the conviction that basic social arrangements are unfair can also move people to activism and resistance -- as we seem to be seeing in the Occupy Wall Street movement. These factors derive from the distributive arrangements of a society: injustice can provoke resistance. Similar statements can be made about state violence and lawlessness. We have seen in Libya, Syria, and Morocco that state violence against protesters can actually have the effect of strengthening and broadening resistance.
So these aspects of injustice can have effects on mobilization and resistance by a population. Are there other effects that injustice can have? As noted earlier (link), Pickett and Wilkinson argue in The Spirit Level: Why Greater Equality Makes Societies Stronger that inequalities of income have surprisingly strong associations with a variety of social ills. This could be developed into an argument that social justice and injustice lead to behaviors that either promote or undermine social welfare.
Finally, it seems plausible to imagine that the intangibles that accompany a harmonious society -- a population of people who generally feel that they are fairly treated by their basic institutions and their fellow citizens -- will lead to a variety of other social goods, including cooperation, civic engagement, and economic productivity. Conversely, it is plausible to suppose that a dis-harmonious society would give rise to the negatives of these qualities: less cooperation, less civic involvement, and less economic productivity.
So two things seem true. First, it does seem possible to "measure" injustice (supported, of course, by a normative theory of why various kinds of inequality are illegitimate). And second, it does seem plausible that the features of a society that constitute its injustice may also have causal consequences for social unrest, social wellbeing, and social cooperation. And these are certainly significant social consequences.
(Perhaps there is an analogous set of questions at the individual level: Is "virtue" a specific empirical characteristic of a person's character? And can virtue be a causal factor in the individual's life outcomes and level of happiness?)