Peter Singer, the Princeton philosopher who maintains that humans have no right to kill animals even for medical experiments, is a bad guy. He makes bad arguments, and he harbors a profound animus against capitalism and Western civilization that induces him to make bad arguments. But they are serious arguments, they must be answered seriously, and the blogosphere has failed, collectively, to answer them seriously.

Singer says, simply, that anything that feels pain has rights. Animals feel pain, therefore animals have rights. So we can’t experiment on them, or eat them, or make coats and shoes out of them.

Richard Posner argued in his dialogue with Singer last year in Slate that Singer’s views are so far at variance with ordinary moral intuitions that we are not obliged to take them seriously. This is of a piece with Dr. Johnson kicking the stone to refute Bishop Berkeley, and is no more impressive from Posner than it was from Johnson. I would find Susanna Cornett’s argument that animals don’t have rights because animals don’t have souls more convincing if I understood exactly what a soul was. (Insert joke here.) And to infer, as Jan Arild Snoen does, the falsity of the animal rights position from its intimate historical relations with fascism and reprehensible behavior of its exponents is a flagrant argumentum ad baculum.

But at least these are arguments. The more typical reaction has been invective. I sympathize, I really do, but this sort of thing gets us nowhere. (I thank Susanna for most of these links, even if I am giving her a hard time.)

Singer is wrong because sentience is not the standard for rights: moral agency is. Rights are the conditions that reasoning beings require to flourish. They are reciprocal because other reasoning beings require these same conditions. Animals have no rights because animals respect no rights, because nature is red in tooth and claw. This is why human beings who violate others’ rights forfeit their own: usually some of them, by imprisonment, or sometimes all of them, by execution, depending on the severity of the offense. A species will acquire rights when its representative asks for them — not because language is the standard, but because it’s as good a proxy as we have for the time being.

Minors and morons have some, but limited rights for the same reasons. They do not fully understand moral agency. When children reach a certain somewhat arbitrary age, they graduate as full moral agents, with concommitant obligations and privileges. Mental defectives have rights exactly as far as they are able to understand the rights of others and act as moral agents. They had to shoot Lenny in Of Mice and Men, remember?

Finally, many people who despise Singer rush to defend the laws against animal cruelty as a way of proving their bona fides. Folks, these laws are a baaad idea. Experiments on animals are cruel, there’s no getting around it — useful, indispensable, but cruel. Today the animal cruelty laws are used against people who turn pit bulls into killers, tomorrow they’ll be used against animal researchers; just as RICO was first used against mobsters, then against stockbrokers. It’s just as cruel to test cosmetics on a lab animal as it is to test them on my pet cat. The only principled, legally sustainable distinction is that my pet cat belongs to me, and the lab cats belong to the lab.