Note: This is Part III, in case you didn't read the title. Read Part I for links to the rest of the series.
The second argument for affirmative action is that it provides role models for people in underrepresented groups. If young black students see a black physics professor, they'll more likely see that physics is "for black people" instead of just thinking of it as white, and the racial disparity among physics professors will decrease. If having black physics professors takes going out of your way to encourage black physics professors by being more willing to hire a professor who is black, if it takes being more willing to accept a black student to a Ph.D. program in physics, if it takes being more willing to accept black undergraduates interested in science, then affirmative action can play a role in providing physics professor role models to young black students.
Additionally, a black professor has some sort of role model effect on white students. If white students see a black professor who is really good at abstract math, it will help overcome a stereotype that black people aren't good at that sort of thing. If white students see a black professor of ancient Greek, they'll come to see that black people are not just isolative separatists who are only interested in a subject because of immediate practical concerns but can be interested in a subject simply because it's interesting. Mostly, though, having a black professor means having a black person in an authority relationship. It's always important when a group is overcoming being viewed as lower on some hierarchy of social relationships to have people in positions that are higher on the social hierarchy. It means having a reversal of the more common relationship many white middle-class Americans have with many black people they have any relation with. It means a different dynamic of affirmation and respect from what some people are used to, and it transforms how they view people. Those are all excellent effects of choices to go out of our way to select underrepresented people for positions they would less likely be chosen for otherwise.
I can't see how providing more role-models for underrepresented minorities can be a bad thing. That's why I think it's good that President Bush went way out of his way to find qualified people for his top positions who came from underrepresented groups. Some see it as pandering, and ultimately whether it is depends on his own motivations. Given his family background (his brother is married to a Latina woman, and his nephew looks pretty much standard Latino), I have a hard time believing that he doesn't care at all about minority groups. He does seem to me to have a color-blind ideal of some sort, though I'm not sure if it's an ignorant naive ideal or a more careful and balanced ideal. He's not one of the best people in public life at making careful distinctions, but I do think he usually has good motivations for the policies he supports and seeks to enact. Even if he did have the wrong motivations, one could argue that the action itself is good even if he wasn't right in doing it.
One problem with this argument for affirmative action is that too often people placed in positions by affirmative action aren't seen as role models for their minority group but rather as sell-outs. I discussed this in my separatism post (about Colin Powell and Condoleeza Rice). The attitudes leading to this view of such people are, in my view, extremely bad ones, and I don't think that we should give in to such views, so this isn't a serious objection, but it's worth mentioning. It does undermine to some degree this argument for affirmative action if the groups these people are supposed to be role models for are seeing anyone successful within their group as a sell-out to white ideals. They're therefore not role models at all to people with that kind of attitude. That's an important consideration, but I can't really think it could undermine so convincingly any good that could come of role models who are in their place because of affirmative action. I don't think it could completely undermine it on its own, anyway. We should be open to seeing if other considerations could enter in to do so jointly with this. Therefore a choice of someone based on race for the purpose of selecting role models (or future role models) can be a good thing, at least in principle, even if it doesn't always have that effect.
This general argument can work the same way at the college level. Admitting more underrepresented minorities can lead to more graduates, who can go on to higher positions in society and therefore serve as role models. The problem in standard college admissions cases is that the standards are lowered enough that to meet the unspecified and supposedly nonexistent quotas for underrepresented minorities at the top schools, the best students more qualified for intermediate schools get pulled up to the best schools. Then the intermediate schools don't have as many students who qualify for their criteria, and they have to take students from lower tier schools. The result is that people are getting into and going to schools they're not prepared for. They don't do as well, and they often don't even graduate. They would do much better and would have a higher graduation rate if they went to schools they were prepared for. As it is, not as many students are graduating and going on to positions that will allow them to serve as good role models. The numbers really do reflect this. At schools with a wider racial gap in SAT scores and grades, there's a lower retention rate among those racial groups that have the lower scores and grades. Some of them drop out of college altogether. Others end up at a college in the next lowest rank, where they'll do fine. I think the objection here is a lot more convincing, because without affirmative action there's more likelihood of the people who would be future role models to actually graduate college with better preparation to get a good job and be a role model.
The biggest problem I have with this overall line of reasoning as an argument for affirmative action is that it's silly to think someone has to be of your ethnic or racial group to be a good role model for you. It's true that seeing someone like Frederick Douglass succeed in the ways that he did could do so much more for a freed slave than seeing white men achieve the same thing, but that's because no examples of black men successful before that time existed before that, and someone might be tempted to think it's not possible. We now know otherwise. We have historical examples as well as current examples. Having more helps, so it's not as if I'm saying there's no argument here, but it's not as strong as it would have been in the time of Douglass. It did have an important psychological effect for many black people in the 1960s to see Nichelle Nichols, an attractive black woman, in as big a role as she had on the original Star Trek series. However, is such a role model absolutely necessary for black people to succeed? Apparently it wasn't necessary for her, since she was the first.
So the force of this argument is mitigated a bit if the idea was that black people (or whatever other underrepresented group you have in mind) can't succeed without these role models put in place via affirmative action (as I think some people really would try to argue). If you merely see it as a good-making factor, then that's different. A good-making factor can be counterbalanced by bad-making factors, however, as we'll see (and as I've already suggested a little bit in that direction already). This isn't an absolute argument, which is going to be true about many of these arguments.