As frustrated as I get with the, frankly, anti-reality stance that many a person has when it comes to opposing the rights of certain groups, I am simultaneously fascinated with it. The reason for my fascination is that there is this weird, abstract way in which all of these matters carry striking similarities with often-observed religious and ritual views on purity, and how these views are often tied in with primitive views on infection.
Confused? Yeah, so was I when I first started noticing this.
Look at how we react to marginalized groups within our society. Let's take homosexuals, because they are currently one of the more marginalized groups in the U.S. If one looks at the rhetoric from those opposed to gay rights, we see that notions of pollution, disease, and uncleanliness are common. Consider:
-There is a pervasive notion that gays will recruit others to their ranks, despite the fact that all of the actual accrued scientific evidence shows that an individual has little-to-no control over their sexual orientation. The descriptions of "gay recruitment" bear a strong resemblance to the spread of a disease, with those who are weak falling prey while an epidemic rages (seriously, go to Google and type in "Epidemic Homosexuality", it's surreal). The notion of pollution is pretty strong, though nonsensical given the real nature of sexual orientation.
-There is an obsession with trying to keep physical and social control over where they go. This applies not only to a wish to not allow them to have jobs such as teachers or from serving in positions such as Scout Master (an opposition that, within the rather weird world of those opposed to gay rights at least is consistent with the widely-held beliefs about "sexual deviants", even if it is inconsistent with reality), but also to pushing for legislation that allows an employer to fire someone based on sexual orientation (or opposing legislation that makes sexual orientation a protected status), which really makes very little sense except as a way of controlling where a person goes.
-There is a "one-drop rule" of sexuality very much in effect (at least for men). If a man has sex with another man, then he is likely to be considered gay or bisexual from that point on, even if he does not consider himself so. However, if you flip it around, a gay man who has sex with a woman just once is not necessarily considered straight or bisexual for that. This is similar to the "one drop" rules of race that were common up through the mid-20th century (one ancestor of a non-white race means that you are of that race), and is also consistent with fears of contamination - fears one drop of sewage might ruin a reservoir of water, or that brief exposure to a sick person might destroy one's health.
-The language used by those opposed to gay rights often speaks of visceral disgust, including gagging, wanting to vomit, etc., all of which is also tied in, again, to our bodies reactions to disease and contamination.
-Even the often-shouted cry of "hate the sin, love the sinner" is couched in a Christian sub-culture in which homosexuality is seen as something to be purged from the individual - whether through ineffectual (and often harmful) psychological treatments or through trying to keep them from being symptomatic, that is by not acting on their sexual impulses. Again, this is in keeping with the treatment of diseased people - treat them, or try to control their symptoms so that they can otherwise get on with life.
Now, in case you think that I am making a case specifically for gay rights issues, I want you to look into the rhetoric surrounding the opposition to the civil rights movement of the first half of the 20th century - while it was clearly the case that African-Americans couldn't stop being their ethnicity, there was a very definite fear of the white population being contaminated by everything from culture (both jazz and rock music provoked outrage when they became popular because of their ties to African-American popular music) to physical contact (there's a reason why "white's only" restrooms, drinking fountains, etc. seemed reasonable to people back then, and it was not unusual to hear about "negro diseases" that might be passed on to unwary whites) to sexual contamination (while it was most common to hear about fears of black men with white women, it was also not uncommon for worries about white men with black women to be brought up). Similar issues have faced other ethnic and social minorities throughout U.S. history, as well as Europe.
I first started to think about this when I was an undergraduate taking a course on the ethnography of India. The caste system of Indian was an important subject, obviously, and as such the role of untouchables within Indian society was heavily discussed. Within the caste system, the untouchables are physically and socially controlled to the extent that they are only allowed certain jobs (those considered polluting, sometimes for obvious reasons - such as dealing with sewage - sometimes for more esoteric reasons - such as working as barbers), are constrained as far as who they can socialize with and under what conditions, and being physically touched by one requires purification, often through ritual bathing*. In other words, the untouchables were treated quite literally as diseased, though carrying a "spiritual" disease rather than a physical one. Even the language used to describe them came directly from dealing with disease, as did the notions of pollution and cleansing.
And understand, this isn't a case of some white kid in California misunderstanding the intricacies of India's religions**. The disease/religious purity interpretation is something that most of the participants in the system themselves were aware of and commented on. Indeed, it was often used as a defense of what was, in truth, a system of religiously ordained bigotry.
Over the years after I took the course, I began to think about my own culture's prejudices in a different way. Not every type of prejudice is based on notions of illness or pollution - anti-Mexican bigotries are generally based on over-simplifications of immigration and population dynamics, for example (though some of these same notions do get pulled in at times). But, very often, the issue of fear of pollution tended to fuel bigotries.
In fact, in the last two decades psychologists have begun to analyse prejudices with an eye towards the tendency for people to express their bigotries by describing the targets in what amount to disease terms. So, it's not just me that has noticed this.
This is both dispiriting, and paradoxically somewhat hopeful. On the downside, the fact that this gets applied across cultures and across time indicates that it is something hard-wired into us, and therefore would be difficult to rid ourselves of. On the other hand, there is clearly no actual connection between the groups of people who are targeted by bigotry and disease-causing agents. So, if you can show this to people and get them to understand what they are doing, it might (and note that I say might...I'm not optimistic enough to say "will") help to dismantle some of those prejudices.
*It should be noted that, since the 1940s, India has been changing radically, and many of the rules regarding caste are not as strongly enforced or held as they once were.
**Unlike the douche bags from affluent areas who go to India "because it's so spiritual, man!"