In the wake of the football-and-racism scandals of the last week (yes, the Barça fans did make monkey noises at Roberto Carlos Saturday night; I clearly heard them twice, and I was watching on TV), I sat down and did a little thinking about racism. It seems to me there are several kinds of what we call racism.
First, and most importantly, there's "moral difference" racism. If you think that, say, Polynesians are subhuman--human defined by you as your own group, of course--and therefore don't deserve the same consideration as any other human being regarding basic human rights like life, liberty, property, and equality under the law, I can't see any mitigating aspect whatsoever to your thinking. You are an asshole and your sort of thinking led to the Holocaust and the Atlantic slave trade and every other enslavement and/or expoliation and/or extermination in human history. This is what I'd call pure racism.
Second is "physical difference" racism. I've decided I don't think this is racism after all. Hey, look, Polynesians are mostly really fat if they live in a wealthy society where there's plenty of food. Statistics bear this out; the fattest countries in the world are not the US or UK, but places like Samoa and Tonga. And a lot of them are physically huge. Is it racist to point this out? This is why you see a good few Polynesians who are successful sumo wrestlers and NFL players. (I vaguely knew one of them, Chris Maumalanga, in college; he was one of my students' roommates in the dormitory. Nice guy.) Also, young Polynesian women are often very attractive, certainly much more so than your typical Midwestern white-bread German-Scandinavian-Bohemian heifers. Is it racist to say that?
Third comes "intellectual difference" racism. This is sometimes considered to be the result of a slippery slope--that is, if you admit there are physical differences between racial and ethnic groups, then you're open to charges that you think there might be mental differences, too. But come on. One look at Colin Powell and Condi Rice and Vernon Jordan and Andy Young and Thomas Sowell and Clarence Thomas should demonstrate that, say, African-Americans are just as bright as anybody else. No one sensible thinks any other thing. Yes, African-Americans on average score lower than other Americans on IQ tests, but my guess is that this is an artifact of the tests and the variable is most likely environment--African-Americans on average grow up in poorer households than whites and therefore sometimes do not have the same access to education and culture as wealthier people do.
Fourth would be "social difference" racism. That is, the group in question has certain social habits that make it stand out from the mainstream. For example, Polynesians love pork, and they eat incredible quantities of Spam. In fact, they tend to like canned meat in general; they sure eat a lot of Dinty Moore Beef Stew. I don't know what's racist about saying that. It's kind of like saying that people from Kansas are often overweight and that they eat huge portions of food in restaurants. That's true. (Note: They actually eat a pretty healthy diet. It's just that they eat way too much of it.) But, see, this is tricky. If you're not tolerant of that particular social difference, or if you're conspiracy-minded and you misunderstand it, then this can be just as bad as (or even worse than) "moral difference" racism. For example, Jews tend to place more value on education and high culture than non-Jewish Americans. This means that they tend to be at least middle-class and middle-income (the two things are different, of course). Ignorant and conspiracy-minded people, who are often poorly educated and uncultured, sometimes resent this and libel Jews as scheming, dishonest manipulators. This leads to very unpleasant results.
Conclusion: I don't think "physical difference" racism is really racism. "Intellectual difference" racism is just plain stupid; it's like believing that the world is flat. "Social difference" racism is often not racist at all; it becomes racist when the social difference is stigmatized, and then it is as reprehensible as "moral difference" racism.