One argument made against affirmative action is voiced by African Americans themselves. These are usually older people who had to achieve--even overachieve--in order to earn scholarships or find good jobs. With Affirmative Action, they observe, younger African-Americans have become more complacent, knowing that they will be given an edge on scholarships and jobs.
Not too many years ago a young Caucasian woman from Michigan took her appeal on a discrimination case all the way to the Supreme Court. She had been denied entrance into the School of Law of a Michigan University even though she had higher scores on the LSAT entrance exam than many minority applicants [this story is in the Time archives]. Because minorities received as much as 40 points for being minorities, they were admitted with lower scores after these 40 points and other points for different categories open only to minority applicants were given to them.
Like so many political policies made in the US, the pendulum swings either one way or the other. In accord with post #3, at this point opportunities are pretty well available to everyone and all "bonus points" should be eliminated.
After all this time, there is no such thing as "justifiable discrimination" because the younger generation must not be made to pay for the faults of previous ones.