It’s common to list racism, classism, sexism, homophobia, and xenophobia together. These are all important and bad phenomena, but they have different logics, and I’m not sure it’s helpful to put them in a single category. Here I explore the differences by focusing on racism and classism.

Older meanings of racism were, I think, always attitudinal. To be a racist was to have negative attitudes toward a racial group, even if those attitudes were unconscious. We now speak of structural racism, which can exist even in the absence of racist attitudes. I sort of wish that we just called that problem “racial injustice,” because the “-ism” suffix connotes an attitude or mindset. But I can accept the linguistic evolution, and I certainly believe that both interpersonal racism and structural racial injustice persist and are destructive.

Classism can be made analogous to the older meaning of racism. You’re a classist if you hold someone in lower regard because of the status of her job, her working-class accent, her neighborhood of birth, or her parents’ social role. Classism of that kind is evident and harmful.

Structural classism would then mean some kind of advantage enjoyed by people due to their class. But this is where the analogy breaks down. Classes are differences in status, power, and advantage. If a society has classes at all, then it gives people different advantages. Put a different way: if a society differentiates among social roles, then it has classes, and that’s structural classism.

Racism is never justifiable, and it’s possible to envision a society that has racial diversity yet no racism. Indeed, I hope that’s where we are headed. In contrast, it’s impossible to imagine a society with classes that doesn’t have “structural classism,” if that means different levels of status, power, or money for different social roles. In theory, we could pay everyone the same salaries, but I’m not sure that would work in practice, and even if it did, it wouldn’t eliminate differences in the quality of work or the status of professions.

Further, classes may be justifiable or even good. Some argue that a classless society is the ideal. We haven’t seen one, however: communist societies produced powerful, detached social strata–the nomenklatura, etc. John Rawls argued that it’s right to pay heart surgeons more than carpenters if (and only if) that is necessary to serve the interests of cardiac patients–who would want highly skilled doctors. Rawls was not perfectly egalitarian, but he was more egalitarian than many Americans, who would make principled and sincere arguments in favor of different pay and status for jobs of different difficulty and complexity.

To say that structural racism exists is to make a critique. To say that classes exist raises the question of whether they are good or bad, and that is worthy of discussion.

One can see the analogy break down in educational settings. A university, for example, ought to be free of both interpersonal and structural racism. It should strive to be a place where your race doesn’t affect how well anyone else treats you or how you flourish. A university cannot, however, be free of class if it exists to provide the education that people need to enter certain desirable professions. If a university prepares people to be teachers, doctors, accountants, and poets, then it is producing a certain class. They could theoretically be paid the same as domestic workers and laborers; they would nevertheless form an advantaged group. A university can strive to reduce interpersonal classism, in the form of prejudice against first-generation students and its own blue-collar employees. But as long as it has blue-collar employees at all, it has classes; and as long as it promises good jobs for its graduates, it generates the class structure. Again, this may be necessary, justifiable, or even good–but it’s no use pretending that an advanced educational institution could be class-free.

Ending racism is theoretically possible and compatible with everyone’s legitimate best interests. You have no right to any advantage conferred by your race, and the very existence of such differences is caustic for all. In contrast, ending class differences might be just, if it’s possible, but it is not compatible with everyone’s interests. We like to talk about “social mobility,” because then we can focus on happy upward trajectories from poor to rich. But for everyone who moves up, someone else must go down. For instance, if the children of domestic workers have a decent chance of growing up to be doctors, then the children of doctors must have a good chance of cleaning houses for a living. Again, we could reduce the disparities in after-tax income and political power, but there will still be winners and losers as long as some people diagnose patients while others clean homes for a living.

Finally, the causation seems to be different. Presumably, interpersonal racism was an original cause (although maybe not the only original cause) of structural racism. We wouldn’t have had slavery, Jim Crow, or redlining if most white people had held most black people in high regard. But today the causal link may be weakened, for structural racism can persist even in the absence of interpersonal racism. For instance, assume that white college grads come to feel benignly and respectfully toward all other races. Still, if each college grad succeeds in getting his own children into a desirable college, those colleges will enroll mostly white students. As long as the distribution of goods in a society is racially unjust, you don’t need interpersonal racism to replicate the inequality; you just need unequal resources plus self-interest.

Meanwhile, interpersonal classism is mainly a consequence of objective differences in income, status, and power. It’s not that middle-class people are prejudiced against working-class people and give them bad jobs. It’s rather that people with bad jobs get treated worse. That pattern can turn into class prejudice, as when a person who has a working-class accent but plenty of money gets treated rudely at a snooty restaurant. But classism of that sort is not the main problem. The main problem is the real distribution of status, wealth, and power in the society. To change that is not a matter of improving attitudes but of redesigning institutions.