Planet of the Apes and Philosophy (3 page)

In 2011, philosopher Peter Singer published “A Planet for All Apes,” a review essay of two movies that had come out a week apart: the documentary
Project Nim
and Amanda Silver and Rick Jaffa's
Rise of the Planet of the Apes
. Singer's essay was a catalyst for this book, and we thank him for his encouragement and help in the early stages of outreach to authors.

K
RISTIN
A
NDREWS

O
ne day, your dog starts to speak in what sounds like some kind of Scandinavian language. She looks at you, cocks her head, and says, “Getum við farið í göngutúr?”

All of a sudden, the familiar has become monstrous. You knew your dog well enough up till now; you looked into her eyes every day and saw her loyalty and affection. But now you look at her in horror. Animals aren't supposed to talk! Worse yet, what is she thinking? What is her
plan
?

We usually feel as though we understand our friends, parents, co-workers, and partners. But when our friends act out of character, we tend to be temporarily baffled. We wonder why they're behaving that way. At least with such people we have recourse to a shared language, which serves as a tool to try to come back to a point of understanding. Without the luxury of a common tongue, gaining understanding of people's unexpected acts is all the more difficult.

This problem is especially salient in the
Planet of the Apes
movies. In the original film, for example, Charlton Heston's Taylor tries to make friends with the mute humans, but in response to Taylor's friendly greeting, they shrink back in terror. Humans aren't supposed to talk! Or in
Rise of the Planet of the Apes
, after Caesar exposes the apes in the San Bruno Primate Shelter to ALZ 113, remember how they gather together in a kind of conference, systematically grunting to one another, planning their uprising? John Landon, the boss of the facility, looks on bewildered. In our world, other apes aren't supposed to plot against us!

When individuals act as they're supposed to act, we feel as if we can understand them even without language. You understand your dog's desire to go for a walk when she ambles up to the door, cocks her head at you, and barks. But when she asks for a walk in Icelandic, that's when you start to worry. New parents carefully study subtle distinctions in the tonality of cries to figure out whether their babies want food, a diaper change, or sleep. Or they download the Baby Cry Translator app. Even with an iPhone, dealing with crying babies can be frustrating, but it is rarely scary. Talking babies, like babies with revolving heads, are another matter all together.

Just as we can understand babies and dogs who can't talk, little children can come to understand us. In this sense, human children can mindread—they can predict what others are going to do, and think about what others want and how others feel. Mindreading is especially handy when someone acts in a way we wouldn't expect, because a developed mindreading ability allows us to figure out people's reasons for acting. Why does Nova touch Taylor's neck, the bruise on her own arm, and then the bruise on Taylor's arm? Zira explains Nova's pantomime by reading Nova's mind: she remarks that Nova remembers the blood transfusion.

A lack of shared language is not the only impediment to our cross-species mindreading success. We also often suffer from a lack of familiarity with the normal behavior of the mindreadee in question. Cornelius first scoffs at Zira's interpretation of Nova's pantomime, and many of our attempts to mindread other species are likewise controversial. For example, when visiting Samboja Lestari Orangutan Rehabilitation Center in Borneo, I got to know a young orphan male orangutan named Cecep, who spent his days in a forest school so he could learn the skills he needed to live in the wild.

Cecep liked to play in the dirt, and the babysitters who took care of the orangutans would often use leaves to wipe the dirt off his fur. One day I watched Cecep sit in front of Anne Russon, a psychologist who studies orangutan cognition. Cecep had dirt on top of his head, and he picked up a leaf and handed it to Anne. She cleaned the dirt off his head with the leaf, just like the babysitters often did. Then Anne dropped the leaf so Cecep gave her another. But this time Anne played dumb, and didn't clean Cecep's head. After a few seconds, Cecep took the leaf
back from Anne, rubbed it on his own head, and then gave it back to her. Anne got the message, so she cleaned Cecep's head again. Anne and I interpreted Cecep's act of handing Anne the leaf as a request to clean his head; he was assuming that there was a shared expectation about what to do with the leaf. When he didn't get what he wanted, Cecep had to elaborate, and pantomime what he wanted Anne to do with the leaf. Anne and I later wrote about this and other instances of orangutan pantomime in the journal
Biology Letters
.

Some scientists think we are unjustified in our interpretation of Cecep's behavior. They do not think that Cecep truly understands the interaction; his behavior is mere mimicry, or coincidence. Without controlled experimental studies, some scientists object, we can't be sure what Cecep is thinking. (We can't even be sure
that
he is thinking.) While some scientists think the problem of interpretation is an empirical problem that could be investigated by different kinds of studies, it is perhaps more accurately described as a philosophical problem. This philosophical problem is that science alone cannot answer the question of what Cecep is thinking, because animal cognition research — like human psychology research — is grounded in folk psychology.

When philosophers speak of
folk psychology
, they mean our understanding of others as people who act for reasons, who have feelings and plans and moods and personalities. Folk psychology is the commonsense understanding of other minds that emerges (in part) from mindreading. But how accurate is folk psychology in the interpretation of other species? Are we right to think that our dog is happy to see us, or that our cat thinks it is time for lunch? What exactly are we doing to other animals when we try to read their minds? And what makes us want to mindread another species in the first place?

One answer to the last question is that we want to mindread other animals because we think they have minds. Philosophers like René Descartes (1596–1650) and Donald Davidson (1917–2003) were never interested in asking what an animal thinks, because they believed that animals can't think. Both philosophers argued that language is necessary for having
thoughts. After all, if someone doesn't have words, how can we characterize what they are thinking using words? What are they thinking in, if not in language?

There are a number of reasons to be unconvinced by this line of thought. For one, some philosophers, such as Jerry Fodor, argue that animals might think in a language of thought, while lacking an external language. We shouldn't assume that because they don't have the kind of language that results in blabber, animals don't have language at all. Alternatively, it may be that animals—and humans—might sometimes think in images, or diagrams, or some other medium altogether; the assumption that humans think only in language might actually be false, too. Indeed, if we accept that babies can think before they're very good at using language, we have to accept that thought without language is possible. At the end of the day, the arguments that language is required for mind often come off as arguments from ignorance—I can't imagine how someone can think without language, so it must be impossible, the critic seems to say.

Sometimes we feel sure that someone has a mind even though they don't talk. Consider how Taylor tries to show Zira that he has a mind. Because he can't talk at first, he has to mouth words in response to her questions. Zira is amazed by his actions, and says to Dr. Zaius “Can you believe it? It looks like he's talking. . . . I could have sworn he was answering you.” Dr. Zaius, ever the good scientist, dismisses Taylor's movements as nothing more than clever mimicry. Then when Zira wonders aloud how Taylor would do on the Hopkins manual dexterity test, and Taylor wiggles his fingers, she is astonished. . . . “Perhaps he understood.”

In this scene, Zira is trying to discern Taylor's mind through his behavior; she's mired in the problem of other minds. Philosophers have long grappled with the other minds problem, which is a question about how we know that other humans have minds. I know that I have a mind, because I directly experience it—I feel my own pain and taste the food that goes into my own mouth. I think my own thoughts. But I can't taste the food you eat, or feel your pain, or think your thoughts. At least not directly. Sure, you can tell me what you're thinking, but maybe you're just a cleverly designed robot. Your speech isn't direct evidence that you have a mind.

There are a couple ways philosophers have addressed the other minds problem. John Stuart Mill (1806–1873) claimed that he knows others have minds because he knows that he has a mind, and that other people are like him in relevant ways. But for each similarity we find between two people, we can find a difference. I'm similar to you because I speak English. But I might be different from you because I have a bad memory, or enjoy eating fried tempeh, or am female. My physical body is probably very similar to yours in a lot of ways, but there are subtle differences between our bodies, including our brains. Because we might be different in important ways, we can't use the argument from analogy to defend our belief in other human minds, much less other animal minds.

Another strategy for defending the existence of other minds is to infer mind in order to explain behavior. If you don't have a mind, I really don't have a good explanation for why you're reading this chapter right now. Just as Zira doesn't have a good alternative explanation for why Taylor is engaged in a conversational sort of give and take, or why he wiggles his fingers when she wonders aloud about his manual dexterity. Why does he do these things? He must understand! Nothing else makes sense of his actions! The apes who want to figure out Taylor finally conclude that he has a mind, because it's the best way to explain the sorts of things he does. Of course, once Taylor starts talking, Caesar starts signing, and Koba writes Jacobs's name on her tablet, others immediately accept that they have minds, totally convinced by their use of language.

But before Taylor uses language, not everyone is convinced by Zira's reasoning. What one person explains by appeal to mind, others explain in other terms. Dr. Zaius, for example, explains that Taylor, “shows a definite gift for mimicry” and he at least pretends to conclude that his explanation of Taylor's tricks is better than Zira's.

To decide whether Zira is justified in her interpretation of Taylor's behavior, or whether Anne and I were justified in our interpretation of Cecep's, we have to do a little philosophy of science. When we explain something a human does (in the enterprise of either folk psychology or contemporary scientific
psychology), we often talk about what she thinks, or what she wants, or her emotions, moods, or personality traits. For most of the twentieth century, the dominant way of thinking in psychology was behaviorism. Behaviorism avoided all talk about unobservable thinking processes or states of mind. For the behaviorists, the idea that scientists could explain behavior in terms of mental states such as
wanting
,
hoping
, or
wondering
was heresy.

Though behaviorism started losing traction for human psychology in the 1960s, it was still going strong in animal psychology. In the 1970s, the biologist Donald Griffin (1915–2003) challenged the behaviorist way of thinking in animal cognition, arguing that we need to talk about animals' mental states to explain some animal behavior. Today, while some use of folk psychology is the norm in animal cognition research, there remain questions about how far we can go.

Scientists are generally happy to say that many animal species do things because of what they perceive and what they remember. Some animal species are thought to learn new things by building associations, and can classify objects in ways that make some scientists think that they have concepts, even if they don't have words. Psychologist Sara Shettleworth, in her 2013 book
Fundamentals of Comparative Cognition
, reviews evidence for learning, concepts, mental maps, tool construction and use, problem solving, numerical understanding, and other interesting capacities in different species. But many scientists deny that non-human animals, despite all of these capacities, are folk psychologists at all.

If these scientists are right, this would make all non-human animals radically unlike humans. From birth, human infants respond to social stimuli such as faces, and engage in the give and take of social imitation. And by four years old, they're already thinking about what other people are thinking! But it's unclear whether other animals understand that there are other minds, or minds at all! Knowing that there are other minds may be important for being able to communicate—after all, why communicate if there isn't a mind to communicate to? So perhaps when Zira thinks Taylor is trying to speak, and when Anne and I think that Cecep was requesting to be cleaned, we're thinking that our respective communicators are also able to mindread. And maybe that assumption is really the problem.

Why do we think young children can mindread? Developmental psychologists usually point to their ability to attribute a false belief to a character in a story. The original false belief task, invented by developmental psychologists Heinz Wimmer and Josef Perner, involves giving the child a puppet show: Maxi the puppet is holding a piece of chocolate, but he wants to save it for later, so he hides it in a box and then leaves the room. While Maxi is out, his mother finds the chocolate in the box and moves it to a cupboard. Maxi returns to the scene, the show is stopped, and children are asked to predict where Maxi will go to look for his chocolate. Children who are able to say that Maxi will look for the chocolate in the box, where he left it, are said to be mindreaders. But most children younger than four predict that Maxi will look for the chocolate in the cupboard, where it is now. The idea is that the children who predict that Maxi will look for the chocolate in the box know that Maxi has a false belief, and in order to be a folk psychologist, you need to know that others have beliefs that can be true or false.