Speciesism is a term that I mostly stay away from in my own work (more for rhetorical reasons rather than philosophical reasons), however it seems to be, I hate to say misunderstood but certainly understood in a very limited way. This post is to unpack this concept a bit and see if it useful. This post is in many ways inspired by this video featuring Kathy Rudy and Tim Morton:
The term itself was coined by Richard Ryder in 1970 in a privately published pamphlet of the same name, but for the most part was popularized by Peter Singer in his Animal Liberation. Speciesism clearly is supposed to be analogous to terms like racism and sexism (indeed, Singer is upfront that the title of the book is to put the animal movement as the next rational movement after something like Women's Liberation). But in what way is the word analogous? Is it that we don't treat people of color well, and we don't treat women well, and we don't treat animals well, so they are all in the same boat? It's a bit more complicated than that.
For Singer racism, sexism, and speciesism is the irrational exclusion of beings from the moral community, or beings that we do not have to give equal consideration of interests (I grant those aren't exactly the same thing). Speciesism isn't just the philosophical insight of Animal Liberation, but underpins the entire rhetorical economy of the book. It was (and continuous) to be the case that those who are concerned for the well being of animals are seen as sentimental and irrational fools while the good rationalist isn't concerned for animals. Look toward the descriptions of Descartes and his followers awful vivisection of animals, or remember your Spinoza, "The law against killing animals is based more on empty superstitions and unmanly sentiment than sound reason." (E4p37s1) Almost all of Animal Liberation can be read as flipping this traditional economy, with irrationality being put on the side of not caring about animals and sound reason being firmly on the side of an equal consideration of interests for animals. Now, sentimentality being connected with women in our culture construct, Singer's original preface has been rightly and largely panned for some sexist and ageist representations (by the way, the most recent edition of Animal Liberation has removed all the prefaces, including the original one, except for the current preface). I also happen to think that sentiment and affect are philosophically more important than Singer does, but that's not the point right now.
So first speciesism serves a certain rhetorical capacity. Moreover, it seeks to displace species as an ethically essential category. Singer performs this function by arguing from marginal cases. In general we have a series of capacities that we claim all and only humans have, and that all other beings do not have. The problem, of course, is that is not really true. First of all, all sorts of animals have amazing capacities (and honestly, the evidence on this one has only gotten more true in the 35 years since Animal Liberation was first published), the ability for tool use, prohibitions on incest, language, denial and disavowal, the ability to paint and dance to a beat, etc. This something I sort of get into in this post. Not only are other animals really incredible, but there is also a great deal of diversity among humans (this tends to be the so-called marginal cases), and that means most capacities that we want to say are definite traits of humans tend to find humans who either never have that power, or at some point in their life have not had these capacities. So, part of what speciesism does is began to contest the boundaries of species. So, species may be real, but they are hardly given and coherent categories, they are not exactly actual. In this sense it might be better to think of species as something like sex. I think we would all agree that there are real and even important differences among the sexes. At the same time, the duality of sexes is kinda bunk. So, there are a multiplicity of sexes, but the coherency of sex, particularly a coherent duality, is a constructed reality (basically see anything by Anne Fausto-Sterling).
In this sense, the critique of speciesism isn't at all about erasing or ignoring differences or about propping up the human/other duality as is implied in the video above, but rather explodes difference. It is actually because of the level of difference (for example, the differences internal to the category of human, and the differences internal to the category of animal). It is actually because of the proliferation of difference that the critique of speciesism has any steam at all. Even in a thinker like Singer we have an explicit discussion of difference in the formulation of equal consideration of interests. This is not a formulation for equal treatment, for the same treatment and the same laws and all of that, but rather the unique interests of beings should be taken account of equally. Of course for many people who espouse a critique of speciesism there emerges certain questions of what allows one in a moral community, and sometimes a support of animal rights in a formal and legal sense. But none of those discussions are necessary to the critique of speciesism (and in this I have a bit of sympathy for Cary Wolfe, who gets criticized in the above video for supporting animal rights--when he doesn't-- and he gets attacked by certain analytic people for not supporting animal rights-- see The Death of the Animal). A critique of speciesism often creates a certain new community, a certain new commonality, but it doesn't do so through a reduction of difference, but rather through an explosion of difference that undermines the coherency of the very category of species. One last thing I want to deal with here is the relationship of speciesism and racism, because that is a central question in Kathy Rudy and Tim Morton's comments above.
There are any number of thinkers that argue that racism's formulation is fundamentally a question of determining who gets to be human. Think here of Foucault in "Society Must Be Defended", Balibar's work on racism, and the decolonial critique of humanism to be found in Frantz Fanon, Aime Cesaire, Sylvia Wynter, among others. Now, none of these thinkers push their work toward including non-humans into the ethical and political community. Indeed, many of them go on to argue for a new and true and real humanism after just a few pages before calling humanism a hitlerism. But for those of us who critique speciesism, I think you can see a certain conclusion. If racism is deeply and obviously tied to a boundary maintenance of this incoherent category of THE human, why try to fight racism by getting the category of the human right? Empirically, we've not been very good at figuring out what gets to count as human (for a more recent example, are Great Apes and dolphins human?). And if a being gets miscounted, placed as an animal or hybrid or pseudo-human or fully human when they are not, what is the big deal? Unless, of course, some of those are beings we are able to exploit, kill, and violate at will and whim. So, why don't we work toward getting rid of speciesism instead of creating a new humanism?
And that last point is a good one, I think. But I want to move away from things I may have argued in the past. It strikes me that racism can still function even in a world without speciesism. I think such racism would be weakened (and vice versa), but I don't think it is as easy as saying that racism is an extension of the logic of speciesism (or vice versa). These ideologies are certainly entwined, but I think it is important to see them as still discrete.