" A moral system based on continuous rather than categorical thinking gives us a biological and evolutionary foundation for the expansion of the moral sphere to include nonhuman animals, based on objective criteria of genetic relatedness, cognitive abilities, emotional capacities, moral development, and especially the capacity to feel pain and suffer. This is, in fact, what it means to be a sentient being, and for this reason I worded the first principle of this science-based moral system as the survival and flourishing of sentient beings. "

― Michael Shermer , The Moral Arc: How Science and Reason Lead Humanity toward Truth, Justice, and Freedom