It’s okay to kill animals because they aren’t sentient/sapient
Animals can sense the world around them just like we can, feel pain just like we can, and they most definitely can suffer, just like we can. Just because animals are not self-aware (sapient) does not give us the right to cause them suffering and death.
The famous quote from Jeremy Bentham is appropriate here:
What else is it that should trace the insuperable line [between those afforded protection by the law and those that are not]? Is it the faculty of reason, or perhaps the faculty of discourse? But a full grown horse or dog is beyond comparison a more rational, as well as a more conversable animal, than an infant of a day, or a week, or even a month, old But suppose the case were otherwise, what would it avail? [T]he question is not, Can they reason? nor Can they talk? but Can they suffer?
- Jeremy Bentham – An Introduction to the Principles of Morals and Legislation - 1789 - p311
Detail - Analytic
Sapience vs Sentience
First let’s clear up some common confusion around the world ‘sentience’.
A sentient being is capable of experiencing things through its senses.
- Collins English Dictionary
So animals are clearly sentient because they have ears and eyes and noses through which to sense the world.
[Sentience vs Sapience] is the distinction between being aware in the sense of being merely awake (which we share with nondiscursive animals - those that do not grasp concepts), on the one hand, and, on the other hand, being aware in a sense that involves knowledge either by being a kind of knowledge, or as potentially serving to justify judgments that so qualify.
- Robert Brandom’s Study Guide to Wilfrid Sellars’ Empricism and the Philosophy of Mind - Harvard University Press - 1997 - p121-122
Sapience is what most people are thinking of when they mean sentience. The ability to know things and reason with that knowledge.
Sapience Matters - Suffering is worse with sapience
It’s okay to eat animals because they are not sapient. The suffering of animals is less because they cannot anticipate their death, or understand that they are going to be slaughtered.
Even if this were true (it’s not, animals at slaughterhouses know full well what’s going to happen to them!) the idea that a hypothetical human’s existential dread while being ‘raised’ for slaughter would be that much greater suffering than an animal’s experience does not diminish the animal’s suffering in any way. It is wrong to cause suffering, it is wrong to take someone’s life away even if they are unable to anticipate it.
- Robert Brandom’s Study Guide to Wilfrid Sellars’ Empricism and the Philosophy of Mind - Harvard University Press - 1997
- Jeremy Bentham – An Introduction to the Principles of Morals and Legislation - 1789