"Drawing the Line" by Steven M. Wise

At the summit is abstract symbol manipulation, which in its fullest form results in language. Wise details the famous case of Koko, the gorilla who knows a thousand words in sign language and seems to use them in a complex way. Even Alex the parrot, with a vocabulary of about a hundred words, is remarkably sophisticated -- for instance, he seems to understand the abstract concepts of color and shape.

In the end, Wise weighs the test results and places the animals on a continuum from 0.0 (mere "stimulus-response machines") to 1.0, full autonomy. Anything with a score above .70, he thinks, should be treated as a legal person with at least some rights.

Honeybees rank the lowest, but even Wise is surprised that they come in at a respectable .59, because of their ability to communicate with one another. Dogs don't quite sneak into personhood, just missing at .68, in part because formal intelligence studies of dogs are rare. But, in ascending order, elephants, parrots, dolphins, orangutans, gorillas and bonobos all make the cut.

But what rights, exactly, should these animals have? Suppose new scientific studies nudge the family dog into personhood. Would it be wrong to chain him up outside when he'd rather run free? To feed him dry food when he prefers canned? To neuter him? Would it be legal to "own" a dog at all? Here, Wise gets a little coy. He admits that asking for too many rights for too many animals all at once is bad strategy. At present, he confines himself to saying that animals with rights shouldn't be captured, confined, killed or made to suffer.

Wise is a pragmatist, and he takes a relatively narrow, legalistic route because he thinks it's his best shot at advancing the cause of animal rights. He agrees in principle with critics who argue that animals should be granted rights based on their capacity to suffer. "But the capacity to suffer appears irrelevant to common-law judges in their consideration of who is entitled to basic rights ... And so I present a legal, and not a philosophical, argument for the dignity rights of non-human animals."

I wonder, though, if it's not the philosophical argument that will carry the most weight in the end. It seems unlikely that many judges will extend personhood rights to animals based on these arguments. More likely, they'll stick to the old, comfortable formulation: People are people and animals are things. (They'll have plenty of wiggle room, once opposing expert witnesses detail the scientific uncertainty behind Wise's evidence.)

Throughout "Drawing the Line," Wise compares the situation of non-human animals to that of slaves before emancipation. Slave owners and others stood to lose greatly if slaves were freed, and a tremendous amount of rationalization went into justifying slavery. Today, we live in a society that depends on the use of animals as things, and Wise thinks we make similar rationalizations.

But it was not legal argument that eventually freed the slaves in the United States. It was a complicated and difficult political decision, driven in part by the belief of enough people that slavery was "philosophically" wrong.

Wise's accounts of animals' mental abilities are fascinating and thought-provoking. But in the end, it wasn't their relative autonomy scores that swung my sympathies. It was the description of Koko making a joke; of a mother elephant involving her youngster in a game so she could complete a task. It was the account of Alex, the parrot, left at the vet for surgery, calling after her keeper, "Come here. I love you. I'm sorry. I want to go back."

Call me an animal lover, call me a shameless anthropomorphizer. But I'm most convinced by the animal rights movement when I'm made to consider that animals can suffer and feel emotion. I think most people are the same.

Only if and when enough people decide that it's morally -- "philosophically" -- wrong to treat animals the way we do, and then translate those beliefs into political action, will there be hope for the sort of sweeping change Wise advocates.

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