Speciesism Hurts Humans Too
It's generally accepted that speciesism benefits humans -- it gives us the psychological benefit of being able to feel exalted above other beings, as well as the physical benefits that come from exploiting animals for various purposes, particularly food. What's more, speciesism can specifically benefit those humans whose status within humanity is lower. People of color, women, disabled people, etc. can all demand an end to their oppression by pointing to the fact that they are just as much Homo sapiens as whites, men, and non-disabled people.
But it seems to me that speciesism hurts at least some humans, as well. (I should caution here that I'm not positing "speciesism hurts humans too" as a primary reason to oppose it, any more than "patriarchy hurts men too" is a primary reason to oppose sexism -- indeed, to treat oppression's negative effects on the oppressor as particularly important seems to reproduce that oppression by continuing to make the oppressor's interests and perspective central. This conclusion is mitigated somewhat when the hurt hits different members of the oppressor group in different ways, because then it has as one effect relieving sub-oppressions within the larger oppressor group. So we can contrast the argument that sexism hurts all men by reducing their ability to love (less important) with the argument that sexism hurts men because effeminate men are mistreated (more important, although still not as important as the greater level of mistreatment that sexism causes toward women).)
In order to uphold a moral hierarchy between species, speciesism must homogenize within species. Rather than thinking in terms of individual creatures, speciesism tells us to treat each individual in accordance with the archetype for that species. Thus the "marginal cases" of individuals that deviate from the species norm, on which so many animal rights arguments rest, are ruled morally irrelevant.
Setting up this single archetype of humanness is detrimental to those humans who do not, or do not want to, fit it. They are simultaneously assured of their rights and reminded that they only get them by proxy since they are not individually deserving of them.
This homogenizing aspect of speciesism can persist even when animal rights are granted. For example, Martha Nussbaum advocates greater rights for animals than Western society allows currently. But she also defends speciesism. She asks us to imagine a person with a case of Down's syndrome whose severity places that person's mental functioning on the same level as that of an adult chimpanzee*. She says the human's case is tragic in a way that the chimp's is not, because the human is deprived by the disease of the higher functionings that normal humans have, whereas the chimp has the normal functionings that you would expect from a chimp. The human is thus entitled to interventions that would improve their functioning (such as intensive therapy and classes), whereas the chimp is not.
Nussbaum's conclusion seems wrong to me. In choosing a person with Down's syndrome as her example (as opposed to, say, a person who sustained brain damage in a car crash), she actually weakened her argument. Down's syndrome is a genetic condition, which the person has had since conception. Being a normal human or a normal chimpanzee are, likewise, genetic conditions. So it's unclear how you would support, in a non-question-begging way, the idea that Down's syndrome is a tragic deviation whereas chimp-ness is normal. Indeed, given the huge population of humans as compared to apes, one could say that chimpanzees are tragic deviations from the norm for members of Family Hominidae.
Speciesism is often analogized to racism, but I think an instructive parallel can be drawn with sex. In most cases, having either male or female physical sex characteristics is not tragic, and no-one would think of wanting to change those characteristics. But in some cases -- both male and female -- those sex characteristics are tragic and there is consequently a reason to change them. I'm talking, of course, about the difference between cissexual and transexual people. The point to note here is that the difference between trans and cis is a subject-centered one made by the person themselves ("I feel comfortable/uncomfortable with the sex organs my body has"), not an objective one based on whether their physical condition is deviant or normal for their category.
To take the trans/cis idea back to the Down's syndrome human versus normal chimp scenario, we have to imagine four cases. A person with Down's syndrome who sees themselves as deviant and wants to be normal is tragic, just as Nussbaum says. But imagine if we were dealing with a person with Down's syndrome who is quite happy with their condition, and has found a form of flourishing consistent with it, and would not want to be made normal. What sense would it make to insist to this person that they are deviant and tragic? On the other side, I would assume most chimpanzees don't aspire to normal-human-ness, and thus having a chimp brain is not tragic for them. But we can imagine a creature who is some sort of "chimp-to-human transspeciesist," saddled with a chimp's brain but wanting to be a normal human**. Such a case would be tragic despite the "normalness" of this creature's brain, and I think we would have a prima facie reason to fulfil the desire to be human if it were possible.
* I have no idea whether this would be a normal, severe, or mild case of Down's syndrome, but my future references in the post to Down's syndrome are meant to apply to this particular chimpanzee-type-functioning level of the condition.
** Perhaps because they were raised in a human home, and thus identify with their human foster parents. I seem to recall reading some things that suggest that apes that have been taught language sometimes prefer the company of humans to that of other apes. This raises some potentially interesting ethical issues about pets that "think they're people."