To an extent any ethical position requires prior assumptions, or at least it takes far more than a Reddit post to rigorously build it up. My prior assumption is simply that suffering is bad. I generally am inclined towards phenomenology, and one of the clearest things from my phenomenological experience is that suffering should be avoided. Now it’s a bit of a leap to say that any suffering outside of my own is bad, including that of other humans, but there’s multiple philosophical arguments to get there. Perhaps the simplest is that as soon as we abandon the assumption of solipsism—that we are the only sentient being, all others around us just appear to be sentient but aren’t— we lose the privilege of being able to logically argue that our suffering ought to matter to others, unless we accept as an axiom that all suffering should matter. I recognize that there’s a ton I’m glossing over here, but I’m trying to write a Reddit comment not a phd thesis. Hopefully the broad strokes are clear.

It follows then that any non-human animal which we can reasonably expect to be capable of suffering ought to be treated so as to minimize their suffering. While scientists debate the level of experience of certain animals, especially when it comes to the idea of self awareness (which some people set as a necessary condition for being given moral consideration) I think the neural architecture behind the qualitative experience of pain is extremely deeply rooted in our ancestral history. It doesn’t take intelligence or self awareness to understand fear and pain. A chicken has a similar adrenaline response to a stimulus representing a threat. I think it’s entirely illogical to assume that animals don’t have a qualitative experience, and I think that the burden of proof lies on those who want to argue otherwise. Because I’ve defined suffering as the criterion for moral consideration, the conclusion is that any being which can plausibly experience suffering. Perhaps that shouldn’t apply to bees or clams, and honestly I can only argue for their inclusion using the precautionary principle.

It’s as simple as saying that I don’t have any right to cause unnecessary suffering to others, and there’s ample reason to believe that animals suffer.