I'm fairly skeptical of any of the social sciences per issues with the demarcation problem and reproduction of results. I'm even more so of studies with any ideological, political, or religious bend to them. That said, with the world as clearly unjust as it is at present, I do wonder who (beyond perhaps the most sheltered and naive of individuals) would still believe that the world itself is innately just? Most Western and Eastern religions teach that it is after we pass on that we are judged, not in this world. Class struggle based secular left philosophy is downright obsessed with the notion of injustice. Perhaps only secular, right, Darwinian philosophies could lead one down this road, and as a formerly right-wing atheist, I can tell you that it's not a very common world view in the least. So I'm guessing this is largely a selection bias for people who haven't thought too deeply about their views or values and are niave to how the world works.
I assume you're talking about social Darwinism when referring to Darwinian philosophies? You might want to specify that to distinguish it from the application of Darwinian thinking to the social sciences, which I think is the right way forward scientifically and has nothing to do with moral judgements.
