What is it like to be a bat? Try imagining it. Perhaps you see yourself being very small, bat-shaped, and hanging upside down inside a cave with hundreds of your friends. But that isn't even coming close. What you really seem to be imagining is you inhabiting the body of a bat, not being a bat. Try again.
If you're finding it hard, one reason is that, as a bat, you have no language, or if we are a little more generous, only a primitive language of squeaks and cries. It is not just that you have no public language to articulate your thoughts, you have no inner thoughts—at least not any that employ any linguistic concepts.
Another reason, perhaps the hardest part of all, is that bats find their way around by echolocation. The squeaks they emit work a little like radar, letting them know what objects are in the world by how the sounds rebound off objects and back to them. What is it like to experience the world in this way? It could conceivably be that the perceptions the bat has are just like our visual ones, but that would be very unlikely. A third reason, even more outlandish, is that the bat sees a kind of radar screen, like that in an aeroplane cockpit.
No, the most likely explanation is that to perceive the world through echolocation is to have a kind of sense experience totally different from that of a human being. Can you even begin to imagine that?
Source: "What is it like to be a bat?" by Thomas Nagel, as republished in Mortal Questions, 1979.
Baggini, J., The Pig That Wants to Be Eaten, 2005, p. 217.
If you haven't come across this issue before, a little more explanation from Baggini will help you understand why this question matters at all. Here's how he framed the issues that are brought up by Nagel's bat:
The scientific study of the mind is really still, if not in its infancy, then certainly pre-pubescent. In many ways we now understand a great deal. In particular, there is no doubt that the mind depends upon a functioning brain and we have come a long way in "mapping" the brain: identifying which regions are responsible for which functions of the mind.
But despite this, somthing called the mind-body problem still remains. That is to say, we know there is some kind of very intimate relation between the mind and the brain, but it still seems mysterious how something physical such as the brain can give rise to the subjective experiences of minds.
Nagel's bat helps to crystallize the problem. We could come to understand completely how the bat's brain works and how it perceives through echolocation, but this complete physical and neural explanation would still leave us with no idea of what it feels like to be a bat. Thus in an important sense we would be unable to enter the mind of the bat, even though we understood everything about how its brain worked. But how can this be, if minds depend on nothing more for their existence than functioning brains?
... What does all this show? Is it that the mind will always elude a scientific explanation, because the points of view of consciousness and science are totally different? Or is it that we just haven't yet devised a framework for understanding the world scientifically that captures both first- and third-person points of view? Or is it that the mind simply isn't part of the physical world at all? The first possibility seems prematurely pessimistic; the second leaves us hoping for a way forward we cannot even begin to comprehend; and the third seems to fly in the face of all we know about the close connection of mind and brain. Finding a way forward seems to be as difficult as thinking your way into the mind of a bat.
So what do you think? What does this inability to be a bat say about the mind-body problem? Send me your thoughts by email, or leave them in the comment section below. I'll be back on Friday to share my own thoughts on this, but if you've been reading my blog closely, you can probably already get inside my mind and know what I'm likely to say...