I divide slurs into two categories:
- Offensive because they have unacceptable connotations (resentment, demonization, denigration, etc.), and
- Words that are offensive because they categorization they imply is wrong.
The first category includes most of the popular ethnic slurs, and have in common that even the people being insulted generally accept the validity of the categories being applied. Plenty of people are offended by slurs for groups like women or African-Americans even as they agree with the person doing the slurring on which people those terms include. For many English speakers in Japan, gaijin and haafu are examples of this – illegitimate terms for legitimate categories (“foreigners” and “biracials”, for those not in the know). Of course, some don’t mind these terms, and in my experience tend to like the experience of being permanent outsiders or see themselves as reclaiming those terms. By the way, Louis CK is wrong though about “Jews” being the only group for which the slur is the same as the neutral term – Muslims have the same problem among certain demographics, and Chinese in Japan do too.
The second type of slur, that of incorrect categorization, takes a bit more effort to think of examples for. According to one of the plenary speakers at JALT 2014, all non-whites were categorized “black” in her part of the US during her childhood, which sadly was not in the 1800s. Many minorities face belligerent grouping by members of the majority, who use catch-all terms almost as if to say they don’t care if El Salvador and Guatemala are different places; they’re all the same as far as they care. I see the terms gaijin and haafu as examples of slurs by incorrect categorization too. And because it’s the categorization rather than the particular term for that group that is wrong, gaikokujin (which many consider more polite than gaijin) and daburu (“double”) are not significantly better.
Quick aside: I once saw a poster for the boy band EXILE that gave one member’s background as ダブル（ハーフ）. At least the math works out.
As for why I consider gaikokujin/gaijin an illegitimate category, first imagine from what kind of perspective that category makes sense to keep in your daily vocabulary. If you believe that all the non-Japanese people of the world have more in common with each other than they have with anyone Japanese, having a single word for all those other people is probably useful. You might find yourself using people’s national/ethnic backgrounds as reasons for doing or not doing some things to or around them, like offering them menus at the restaurant you work at or cheering for them as they play your national sport. You might also assume that anything true about you can’t also be true of one of them – that they might eat fish, live with their grandparents, or display hospitality, which without that category marking them off you might just assume many people do everywhere. The fact that these two words gaikokujin and nihonjin are defined against each other implies the two groups have very little in common. If you were educated after the 1950s, there should be many salient characteristics of people that should occur to you before thinking to mention that they’re not Japanese. Someone’s being Japanese or not is almost never a reason to think anything else about them. In other words, if you use the word gaikokujin often and you don’t work at an airport, you’re probably unduly ignorant and parochial for someone living in 2016. And people who are not Japanese and call other people gaijin are borrowing this backward parochialism and making it their own. I understand the impulse to show affinity for the culture you live in, but this part is probably a huge step back from your home culture.
In order to believe in the correctness of the terms haafu or biracial, you have to believe that other people are monoracial. Other people have 1, and you have 1/2 of each (or 2, which seems like cheating). Of course, nobody is monoracial. Even people who believe themselves to be so can only honestly say that they don’t remember their last ancestor who didn’t fit in the same racial category that they do – and if you go back more than 2000 years in Japan everyone’s ancestors were somewhere else. It’s mistaking a lack of records for purity. The fairest definition of monoracial is “what other self-described monoracials are willing to accept”. Not exactly firm foundation on which to stake one’s (or one’s children’s) identity. The group of people that multiracials (or haafu, biracial, bicultural, etc.) comprises is everybody or nobody – not just the Japanese folks with one English-speaking parent. And of course homogeneity is as much a myth as the monoracial.
One of the most memorable phrases I’ve read in the last few years is “those who imagine themselves to be white”, from Ta-Nehisi Coates’ Between the World and Me. This is his term for what are normally called just “white people”. I don’t see why the implications of the phrase can’t be expanded to all people – after all, if there’s anything every liberal college graduate learns, it’s that all races are social clubs that have a phenotypic minimum requirement; they are not phenotypes themselves. Using the terms gaijin/gaikokujin or haafu says some uncomplimentary things about how you imagine yourself and what characteristics you find important in other people. It’s better not to use them, but not because they’re slurs in the usual sense of being inherently insulting – they just make you sound like you got your view of humanity from pre-World War 2 social studies textbooks.