In an otherwise interesting review of recent books on animal ethics, philosopher Lorna Finlayson writes:
Singer more than once claims that his arguments are binding on anyone receptive to evidence and basic logic (resistance can only result from ignorance, speciesist prejudice and self-interest). But it seems odd for him to say, as he does towards the end of the book, that the claims of Animal Liberation Now ‘at no point ... require acceptance of utilitarianism’. His arguments often look like utilitarian arguments; they are certainly not, for example, religious or Kantian ones. But for most people ethical questions are not settled by a simple utility count.
This is quite extraordinary. Imagine a parent telling their child not to torment a stray animal. “Why not?” the child asks. “Because you’re hurting it!” the parent replies. They might add: “And you shouldn’t cause pain without a really good reason.”
Is the parent thereby a utilitarian? The reasons they’re pointing to “are certainly not, for example, religious or Kantian ones.” They’re reasons that utilitarians recognize: reasons of beneficence, or non-maleficence. But that doesn’t make them exclusively utilitarian reasons. Every sane moral view recognizes reasons of beneficence and non-maleficence. If you don’t, you aren’t just a non-utilitarian: you’re a psychopath.
What’s distinctive about utilitarianism is not that it recognizes reasons of beneficence and non-maleficence, but that it recognizes no others. A Rossian pluralist also recognizes reasons (or “prima facie duties”) of beneficence and non-maleficence, but adds further reasons of fidelity, gratitude, and so on. But those further “deontological” reasons don’t conflict with our obvious reasons of non-maleficence to not torture animals. So that’s why Singer says, 100% correctly, that his arguments in animal ethics in no way depend upon acceptance of utilitarianism. You can be a Rossian pluralist, or a minimally decent person of any other theoretical stripe, and you should still agree with the utilitarian that we have decisive moral reasons to not cause suffering without sufficiently good reason.
(If anything, these reasons are likely to be stronger for deontologists, since they give extra weight to causing harm relative to either allowing it or to granting benefits. For utilitarians, by contrast, there’s nothing special about causing harm. The strength of my reason to avoid hurting an animal is equal to that of my reason to positively benefit it by a comparable amount, all else equal.)
Conclusion: Utilitarianism as a moral theory can be broken down into a commonsense core and a very controversial exterior. The commonsense core is beneficentrism: the claim that we have strong moral reasons of beneficence (and non-maleficence) to help others and make the world a better place. The controversial exterior is the rejection of all other reasons, especially:
The rejection of deontic constraints, e.g. against harming as a means.
The rejection of special obligations and reasons of partiality.
Non-utilitarians think that utilitarianism goes wrong in these two ways. Pluralists should (like W.D. Ross) instead build upon the beneficentric core of utilitarianism by adding the other reasons that they think utilitarianism is missing. But for goodness’ sake, don’t go the psychopathic route of denying that we’ve any reason to help others, or to reduce suffering, at all.
I like to poke people in the eye for no reason because claims that one shouldn't assume a controversial utilitarianism.
Even Kantians accept or ought to accept a wide duty to promote other people's well being.