What's your most important possession? Your phone, your laptop? I'd argue that your most important possession is your mind. Your mind lets you both think and feel. Without your mind, you wouldn't even be you. Your mind allows you to think through problems, to make decisions, to appreciate the color of the sunset and to feel the rush of a kiss. Your mind may be indispensable to you, but it's actually invisible, and insubstantial. If we cut open your head, we would see your brain but wouldn't see any thoughts or feelings. And that's because thoughts and feelings arise at the interconnections of millions of neurons. As an analogy, when you look at this computer screen, you see thousands of rich colors. Now let's suppose you tore open your computer to find these colors. You'd find only a bunch of electronic transistors. That's because colors and icons and videos and word documents, are all products of the interactions between these little transistors. Your mind works the same way, just with interactions between neurons. Now, because thoughts and feelings aren't physical things like brains or microchips, it's difficult to know exactly what people are thinking or feeling. Sure someone can tell you that they're sad, and maybe even back it up with some tears. But how do you know they're not just a really good actor? If someone says they love you, how can you ever really know that they do? You can't, because people's minds are ultimately inaccessible. Philosophy calls this "The Problem of Other Minds". This problem not only makes it hard to know whether people are telling the truth about their feelings, but it also means you can't be sure whether people even have feelings. This uncertainty on other minds isn't such a big deal with friends and family. You can be pretty sure that your mom and your best friend have thoughts and feelings. But what about a cow or a corporation or a computer. Can they think and feel? Do they belong in the mind club with you and me? What about your pet dog or cat, do they have a mind? You might immediately say yes, but how can you be sure? And would anyone else agree with you? Your neighbors or your cousins might just see your pet as a furry machine that converts kibble into poop. Questions of mind and pets can be funny, but they're deadly serious when they concern other people. A doctor might see a vegetative patient as gone and recommend pulling the plug. But the family, instead, might see them as somewhere still in there, and want to keep them on life support. The fact that people can disagree about the minds of others suggests that, in many cases, minds are a matter of perception. And so because thoughts and feelings of others are invisible, it's up to each of us to perceive them, or not. Now, mind perception is immensely important. Because entities with mind are afforded moral status, whereas entities without minds are treated as merely things. Historically, when people argued in favor of slavery or religious war or sexism. They argued that people of different races, religions or genders had different minds, less minds than themselves. As a more everyday example, consider how vegetarians and meat eaters see the minds of pigs. If you see pigs, like Wilbur from Charlotte's Web, as smart and sensitive and caring, then the thought of eating bacon is likely repulsive. But if you see pigs as mindless meat machines, then the thought of eating bacon is instead delicious. A similar difference in mind perception underlies abortion. For those who are pro-choice, they see fetuses as a mindless mass of cells. Whereas those who are pro-life see fetuses as tiny babies with legitimate human minds. So if mind perception is so important, you may wonder how exactly we see the minds of others. Until recently, it was thought that mind was perceived along a single dimension. On the low end were things that were clearly mindless, like turnips and tables. And on the upper end were things that clearly had a mind, like people and God. Now in between these two extremes, were things like plants and insects and animals and babies and children. And together this formed what we historically called "The Great Chain of Being.", a single dimension. But is this true, do we actually see minds like this? I wanted to test this scientifically. So my colleagues and I conducted a study with thousands of people. We introduced people, these participants, to 13 different characters, including an adult man and woman, a baby, a fetus, God, a dog, a robot, a dead person, among many others. We then had them rate each characters on a variety of mental capacities. Capacities like the ability to feel pain or pleasure or fear, to remember things or to plan for the future or to have consciousness. We then looked to see which mental capacities clump together. Now if mind perception progresses along single dimension, this great chain of being, then all of the capacities should hang together. And this would mean that characters seen as highly capable of pain and fear, having ability to feel, should also be seen as highly capable planning head and remembering things. But that's not what we found. Contradicting centuries of thought, we found that minds were perceived along two dimensions. This first dimension was what we called experience. It's the ability to sense and to feel and to really have inputs from the world. It's the ability to feel pain and pleasure and fear. The second dimension, we called agency. It's able to act, and to think, and to do, to remember and to plan for the future. It's really the ability to act upon the world. So you can think of experience as inputs, and agency is kind of outputs. Now we can use these two dimensions of agency and experience to make a graph, or a map, of different minds. Now here in the top right corner you have adult humans, entities like you and me, perceived to have both agency and experience,to be able to both think and to feel. Over here, you've animals and babies, perceived to have experience, but less agency, to have feelings, but less ability to think and plan. Now in the opposite corner down here, we have got incorporations like Google, who are perceived to have lots of agency, lots of capacity to act and do, but generally seen to have little experience. We seldom think of God, or Google, as feeling pain or being hungry or feeling embarrassed. Finally, in this corner, we have the dead person, perceived to have both little agency or experience. But note that they're not at zero, people still think that the dead still have some amount of mind. So, mind is perceived along two dimensions. Now you may wonder, why does it matter? Well, as I mentioned earlier, mind is the key to moral status. And so, if mind is perceived along two dimensions, then so too should morality. And this turns out to be true. Our research also reveals that moral status splits into two. And each of these two senses of moral status maps onto the two dimensions of mind perception. And so, when we see someone as having experience, the capacity for feeling, we give them more moral rights, and we seek to protect them. So for instance, babies have experience, and we seek to protect them and see it as wrong to harm them. On the other hand, when we see someone as having agency, the capacity for thinking, we give them moral responsibility. And we hold them accountable for their deeds, and prosecute them if they do something wrong. For example, corporations have agency and we punish them when they harm their customers. So not only did our mind survey show that minds are perceived along two dimensions, it also predicts moral status. Now this two dimensions of minds and morality will become the basis of our discussion in the next section. But for right now, the important point to remember is that minds are perceived. Now because of the problem of other minds, whether a dog or a coma patient can think or feel, is less a matter of fact and more a matter of perception. Understanding that minds are ambiguous and a matter of perception, actually gives us the key to helping to bridge moral disagreement. We often think of those who disagree with us, in a moral sense, as monsters, whether it concerns issues of abortion or euthanasia. However, it's important to understand that everyone cares about protecting the thoughts and feelings of other people. Everyone knows that babies and animals deserve some kind of moral rights. But what the key is, is that we often disagree about who or what actually has thoughts and feelings, about who or what has a mind.
