You're attacking what is a common argument by black conservatives to attack Bachmann and it is pathetic.
Actually, that is not the point that Walter Williams is making. He is making the point that in 1925, 85% of black families had two parents. Those parents were likely born at the turn of the century to people born just after slavery to people born during slavery. So those families in 1925 were 3 generations away from slavery.
The point he is making is that black families were better off (having 2 parents) in the 1st quarter of the century than are are now. None of his argument suggests that they were better off during slavery, and he is actually suggesting that current black race hustlers stop blaming slavery, because the black families were able to overcome it within 3 generations, just to fall back into it after the welfare state.
No where does he say that “slavery didn’t harm the black family as measured by the census after it occurred....”