In a fascinating opinion piece in the New York Times this past weekend, neuroeconomist Gregory Berns writes: “For the past two years, my colleagues and I have been training dogs to go in an M.R.I. scanner — completely awake and unrestrained. Our goal has been to determine how dogs’ brains work and, even more important, what they think of us humans. Now, after training and scanning a dozen dogs, my one inescapable conclusion is this: dogs are people, too.”
As Berns explains, his research found a striking similarity between dogs and humans in the structure and function of a part of the brain known as “the caudate nucleus.” It was previously known that in humans, the caudate plays a key role in positive emotions, including the anticipation of things we enjoy, such as food, love, and money. What Berns and his colleagues discovered is that in dogs, the caudate is activated when they are exposed to hand signals indicating food, the smells of familiar humans, or the return of their owners. While Berns emphasizes that these findings do not “prove that dogs love us,” he concludes that “using the M.R.I. to push away the limitations of behaviorism” suggests that dogs have “emotions just like us.”
There is much thought-provoking material to write about in this opinion piece (including the fact that they “treated the dogs as persons,” with consent forms, the right to withdrawal, etc.), but what I want to focus on in this post is the premise that neuroscience can resolve contested questions about the existence of mental states—in animals, or even in humans.
The allure of this use of neuroscience is that it seems to work around a classic philosophical problem known as “the problem of other minds,” which refers to the puzzle of how one knows whether someone or something, other than oneself, has a mind. Arriving at a philosophically satisfying answer to this question is more difficult than it might seem. The core difficulty is that the behavioral criteria that we use to infer the existence of mental states can be misleading. For example, someone may behave as though he is experiencing positive emotions because he really is experiencing them, because he is pretending to do so, or (perhaps in the future) because he is a sophisticated form of artificial intelligence designed to do so. The problem, in short, is that mental states and behavior are only contingently related.
Neuroscience seems to provide a solution to this problem by allowing us to look at a relationship that is not contingent: the relationship between mental states and brain states. For example, in Berns research, the idea is that if a dog’s caudate nucleus is activated when it is exposed to emotion-inducing stimuli (i.e., the brain state is present), this constitutes evidence that it is experiencing emotions (i.e., the mental state is present). As Berns writes: “By looking directly at their brains and bypassing the constraints of behaviorism, M.R.I.’s can tell us about dogs’ internal states.”
Yet I wonder whether the neuroscientific approach really provides a solution to the core problem of relying on behavioral observation. After all, the only way in which we can infer the existence of the connection between brain states and mental states in the first instance is by reference to behavior. For example, we believe that activation of the caudate nucleus is associated with positive emotions in humans because humans are able to report or behave as though they are feeling these emotions. Thus, it seems that the strength of neuroscientific claims about animal minds rely in part on the strength of the behavioral observations that underlie them.
This is not to suggest that neuroscience cannot provide valuable insights into mental states, but rather that it is a mistake to think that neuroscience provides a solution to the problems associated with relying on behavioral observation. The mistake is thinking that when neuroscience allows us to observe the brain, it is also allowing us to observe the mind.