Far from presenting any threat to human dignity, animals and their moral claims upon us — the basic obligation never to be cruel, not just the option to be kind when it suits our purposes — are a constant hindrance to human presumption. What is the mark of that special status of ours, anyway, if not precisely the ability to be just instead of merely dominant, to be the creature of conscience and bring mercy into the world? A loving concern for humanity that stops there, instead of spreading outward in a sense of fellowship and active respect toward “our companions in creation,” to borrow a lovely phrase from Pope Benedict, is too close to self-worship, and bad things come of it.

Animals are always getting in the way of prideful and willful people, who act as if all things exist for their pleasure and expect everything to yield to their designs and appetites, no matter how base or disordered. In that way, a dutiful regard for animal welfare helps keep us humble, as a natural check against all of mankind’s own endless fiats, much as the duty to put the interests of children first can steer adults and entire societies away from all kinds of destructive self-indulgence. No group bears a heavier duty of self-restraint toward other creatures than the people who farm them, and John Paul II, in a 2000 address, had a message specifically for modern agriculture: “Resist the temptations of productivity and profit that work to the detriment of nature. When you forget this principle, becoming tyrants and not custodians of the Earth, sooner or later the Earth rebels.”

Cruelty is less a vice in its own right than it is a cost exacted by other vices — greed and arrogance, just to start with. Victims of cruelty are the wreckage left by selfish desire. So often the easiest, most helpless victims are children and animals. Cruel people often quite sincerely protest a feeling of innocence, expecting to be judged by intention rather than by objective consequences — by what they prefer to think they’re doing, instead of what they are doing in reality. Wrongs get endlessly rationalized, power turns to tyranny, so that even Kermit Gosnell, somewhere in the back of his mind as he was killing infants who had survived abortion attempts, may have felt himself to be a faithful servant of Progress and Reproductive Choice, doing work the world approved of even if it preferred not to know all the details.