During the environmental movements of the 1970s, philosophers began pushing boundaries. In 1975, Australian philosopher Peter Singer published Animal Liberation . While Singer actually identifies as a preference utilitarian (a welfare position for sentient beings), his work argued that the capacity to suffer—not intelligence—is the prerequisite for moral consideration. He coined the term "speciesism," comparing discrimination against animals to racism or sexism.

Pragmatists argue that waiting for the world to go vegan is a luxury the animals in the slaughterhouse today cannot afford. They argue for Proposition 12 style legislation (like California’s ban on extreme confinement). This improves millions of lives immediately, even if it doesn't end ownership.

History shows that welfare reforms are the gateway to rights. As the public grows uncomfortable with factory farms, they switch to "cage-free." As they realize cage-free still involves debeaking and high mortality, they switch to "pasture-raised." Eventually, they realize the logical endpoint is plant-based. Conclusion: The Moral Universe The arc of the moral universe is long, but it bends toward inclusion. Two centuries ago, the law allowed the torture of cats and dogs for entertainment. One century ago, laboratory animals were considered "animated tools" with no legal standing. Today, several countries have recognized animal sentience in their constitutions.