The principle of equal consideration of interests—according to which similar interests deserve similar weights in our moral deliberations, regardless of whose interests they are—appears to have uncomfortable implications. If, for instance, humans and hens have equally strong interests in continued existence, then in lifeboat cases where we have to choose between saving humans and saving equal numbers of hens, it could work out that, according to some moral theories, we ought to flip a coin.
Many philosophers have wanted to avoid such implications. Some have argued that humans and many nonhuman animals have different capacities for welfare—that things can go better and worse for humans than for many nonhuman animals and, therefore, that humans often have more at stake in difficult tradeoff cases.
Tatjana Višak disagrees: her new book offers one of the few sustained defenses of the idea that all welfare subjects have the same capacity for welfare....
