Me and this mexican boy had an argument and...?

Honestly, it seems to me that the argument had nothing to do with supposed "races" or anything...since you said you forgot the subject anyway. However, as for your point, I doubt that many white people are really scheming over how the other "races" can be oppressed and held down. Mostly, I think people put themselves down and blame it on others because it's easier. If you were arguing, is there no possibility that you were to blame rather than "the white man"? Therefore, people should be willing to accept responsibility for their own actions instead of jumping to conclusions. What you say is possible, but it seems to be lacking in probability.