Thought experiments are often useful at revealing hidden biases and inconsistencies in our reasoning. Here’s one to consider.
Imagine a child is born. This child has a rare genetic defect, such that his cognitive capabilities are severely diminished. His parents, being of poor financial means, put him up for adoption. Due to recent legislation, the couple who adopts him can claim a hefty tax exemption. They adopt the child for this reason and this reason only – not out of a desire to care for a less fortunate child.
As the child matures, the specifics of his impairment become more obvious to the parents. While he’s able to communicate in some form, he definitely cannot learn any real language. All he can do is, on occasion, express desires via non-language sounds. He’s also unable to learn any higher reasoning skills, such as counting. He can, however, learn (with some difficulty) the locations of a few important objects around the house. He can feed himself, but not cook or use silverware (and when he does feed himself, things can get pretty messy). Finally, he can express some basic emotions – most notably, happiness and fear. Higher-level emotions though, such as love or anticipation, seem completely foreign to him.
Now imagine that these parents, finally getting fed up with the difficulties of raising this childs, bring him over to your house. “Here, take him!”, they say. They don’t want anything to do with him anymore, and if they’re being honest, they don’t much care what happens.
Now, you have a choice. You could care for the child yourself, or you could find someone else to care for him. Or, you think in a moment of wild speculation, you could just knock him unconscious, slit his throat, and throw him in the oven.
If you’re like me, that last option horrifies you. It would horrify any rational person. But this thought experiment is strongly analogous to how society treats animals raised for food every day; and the child, with his severely diminished cognitive capacity, is strongly analogous to a pig.
The disabled child and the pig may seem very different at first glance, but consider carefully what exactly those differences are. They’re both alive, in the sense that they’re both biological organisms with metabolic processes. But this isn’t morally relevant – plants and bacteria also have this trait. They also both have similar cognitive capacities.
There are differences, but these differences aren’t ones that are morally relevant. For example, the pig and the child look different – but so what? Furthermore, they have different DNA; but again, so what? Whether something has human DNA isn’t relevant to how we should treat them. A corpse, a skin flake, and a blastocyst also have human DNA, and we don’t think we should treat them in the same way we treat adult humans (some people will disagree with me on that last one, but oh well. that’s a different debate).
In these cases, the morally relevant feature is nothing but cognitive capacity. We don’t strive to treat corpses and skin flakes as moral agents or moral patients whose rights need to be respected, because they don’t have any cognitive capacity at all. Likewise, we do strive to respect the rights of the other members of our society – because they have cognitive capacity.
In the case of the child, we do in fact think there are rights that need to be respected – and perhaps, since the child is so unfortunate as to have cognitive capacities, but ones far less than our own, we might even go above and beyond in caring for this child. We wouldn’t ever dream of killing and eating this child, even humanely, simply to satisfy our own desires – desires which can be satisfied rather easily by other means.
But if that’s the case, then we should treat animals the same way. Unless, of course, you think it’s permissible to eat the child.