The Root Cause?

So I am currently reading The Better Angels of our Nature by Steven Pinker. In a nutshell this is a book that wishes to explain that today's world, particularly the "western world" is far less violent than the world of antiquity (including the old "West") or even the recent past. While I will reserve commentary on the overall summary until I've finished reading the entire 1007 page tome, I will take the time to comment on one aspect that I've noticed from the first 200 pages.

Pinker generally asserts that as humanity moved from "nature" to settled civilizations with stable governments which featured a monopoly on violence, the levels of violence in those societies (measured in the book by the rates of homicide expressed as x per 100,000 persons) decreased. His data shows that Western Europe enjoys the lowest levels of violence (less that 1/100,000) and America, while relatively safe is at a "shocking" 10/100,000 or thereabouts.

When we look closer at the American data presented we are shown that in early American history violence by European-Americans and African-Americans (blacks) were about equal but as you moved through time the levels of violence among African-Americans increased (or failed to decrease) while that of European-Americans declined. Of note was that both Southern blacks and whites were and are both more violent than their northern counterparts but that is not the focus of this entry. So what is the focus? If Pinker's data is correct then the violence seen by the African in America cannot be explained by culture or lack thereof. Nor can it be explained by "inherent" predispositions on the part of the African. Clearly the "fact" that Europeans and Africans of America's early history exhibited the same level of violence means something else is at fault. We are forced to ask why Black violence in America is so high. Pinker, prior to disclosing the data explains that the success of the Leviathan lies in the ability of the state to not only foster an environment where people can conduct profitable business but where the state is trusted to mete out fair justice to all parties. The ability to provide justice (and protection) would be the means by which interpersonal violence is prevented in a society. Any somewhat bright person would see that in the case of the African in America the state totally failed on both grounds.

While we can agree that the American state became very efficient at creating a safe environment for it's white subjects, It is clear that it did not do so for it's African ones. While the state encouraged business creation and ownership among it's European citizenry as well as providing "justice" and "safety"; when it was not making it's black subjects into property, it was allowing African persons to be killed with impunity and stripping them of so called "god given rights of man".

If Pinker is correct that the reduction in violence among white citizens of the United States was a result of a more effective and "fair" state apparatus, then it can also be argued that the 500+ years of a state apparatus that acted to dispossess the African and clearly disfavor him in the courts is directly responsible for the levels of violence seen in African-American communities.

If we cannot make this argument then Pinker's entire thesis is worthless, no?