You make a lot of good points, but there are five that you should rework.

(1) You have to be really careful arguing that disliking a culture is "racist". Otherwise, anyone (e.g. white people) can correctly claim that if you don't like how they do things, and those things are part of some culture, you're racist. (I think this is a completely unhelpful way to use the word, but it's the logical inference from your arguments as they stand.)

(2) If you think that simply believing that (some) black people have a problematic culture is going to make it impossible for people not to be biased against black people, don't you have to also believe that simply believing that black people are more likely to commit murder (statistics are very clear that they have done so in the past) will also make it impossible? I don't understand what you're getting at with this argument. I don't think it's particularly true (maybe it does have some truth to it), but it's super-depressing if it is true. Are you sure that we can't learn to treat people as individuals even if they belong to some group whose averages show some trend in some direction? Aren't we supposed to judge people by the content of their character?

(3) With your marathon analogy, and several others, you completely neglect social mobility. Perfect social mobility is running a new race every generation. Zero social mobility is running a continual race since 350 years ago. Actual social mobility is in between. It's a good analogy, but it needs to be tempered a little.

(4) The point about personal responsibility is surpassingly weak. "You are responsible for all the actions of your ancestors that still have consequence today" is an untenable, unbearable burden. It also strongly contradicts the "personal" part: that people should act and be judged by who they are, not by the tide of history that they happen to find themselves in. For instance, do we demand that the decendents of African kings who sold other Africans into slavery are now responsible for the conditions of the decendants of the slaves? Do we hold the ancestors of Cortez and his men responsible for the destruction of the Aztec empire and any poor conditions of the decendants of the Aztecs? Do we hold the Assyrians responsible for the brutalization and murder of so many of their neighbors, including the deaths of many Jews? You need to clarify what is a reasonable expectation, or use arguments not from personal responsibility but from compassion and justice. That is, if things remain unjust _now_, it is the duty of those here _now_ to seek greater justice, regardless of history.

(5) Question 20 uses a silly analogy. Human society is not a simple physical system. Newton's First Law isn't even intuitive, or Aristotle would have gotten it right. Just use something else. Anyone who believes that Newton's First Law applies to the socioeconomic universe is utterly deluded...so you're making exactly the opposite point that you want to. (That is, you're arguing that people who think there are lingering problems are so hopelessly clueless about the distinction between the motion of physical objects and the propagation and development of culture and society that their views should be completely ignored as irrelevant.) If you want to use the analogy, at least use it loosely ("inertia"), not strongly ("Newton's First Law").