I’m currently teaching a course called The Mind-Body Problem, which focuses on neuroscientific approaches to understanding consciousness. Needless to say, it’s not lightweight material for undergraduates, though it does lead to a few dorm-room style philosophical bull-sessions of the type one romantically associates with academia.
The mind-body problem is not particularly easy to even define. In a nutshell, it is this: how does the physical brain give rise to subjective experiences?
That’s it in a nutshell, but the phrase “subjective experiences” doesn’t always convey the problem. Nor does the word “qualia”, nor does the expression “what it is like”, which is more philosophical jargon that attempts to define the issue.
So usually the mind-body problem is described through thought experiments. There’s any number of wonderful ones. Here’s a short list.
Mary The Color Scientist. (Frank Jackson.) We are asked to imagine Mary, a scientist who is raised from birth in a black and white room. She is never exposed to any “color” whatsoever. However, she studies the visual system, and comes to know every relevant fact about the way our eyes and our nervous systems respond to different wavelengths of light. At some point, she is released from the room and experiences color for the first time. We are asked to decide whether this experience comes as any surprise, whether she learns anything new by the experience. Does she think, so this is what red is like? Or does she think, Ah yes, this is just how it is supposed to be. If your intuition is the former, the mind-body relationship becomes a mind-body problem: Mary truly knew everything about the brain’s response to light, but nowhere in that knowledge is the explanation for her experience of red.
The Chinese Room. (John Searle). A man is locked in a room. (Philosophical thought experiments apparently do a lot of locking people in rooms.) People pass slips of paper into the room which are covered in squiggles of ink. The man in the room has a gigantic dictionary in which he can look up the squiggles and receive instructions for a second set of squiggles which he draws on a new sheet of paper and passes back out of the room. In reality, the squiggles are questions written in Chinese, and the man’s book has told him how to answer the questions, also in Chinese. From the outside of the room, the man appears to understand Chinese, but in reality, the man in the room is just performing an automatic task, and has no understanding of Chinese. Searle originated this thought experiment to describe the behavior of a sophisticated computer or robot. Imagine a sophisticated robot that can answer questions posed to it in English. Does the robot understand English in the way we understand it, or is the robot merely executing a program, without any internal flicker of what it is like to have understanding? We seem to be trapped into admitting one of two things: either the robot does understand English (in which case we have to ask how that was built into the robot – which circuit made it conscious?), or we are just machines like the robot executing our own programming.
Zombie Earth. (Thomas Moody.) Imagine an organism exactly like us but without any inner life, no subjective experience. (For some, a robot would fit the bill.) Call it a zombie. This zombie could stop at a red light and zoom through a green light, not because it experienced red or green, but because its visual receptors responded differentially to wavelength and because this response triggered the appropriate operations of the zombie’s foot. It is possible to imagine, goes the thought experiment, that everything we do with a conscious experience could, in principle, be done without it. But now imagine, says Moody, a world full of such zombies. Would this world really be exactly like ours? Our would there be differences in culture, if not in behavior. For example, could we imagine a zombie, born on zombie earth, ever posting a blog about the mind-body problem? Isn’t the mere fact that we think about these issues, when in principle we might not, evidence that consciousness is something that cannot easily be explained without resorting to dualism?
The Star Trek Transporter. One of the first things I try on my students is to ask whether they would be willing to use a Star Trek transporter. In the picture above, Kirk, Spock, and McCoy are about to be dematerialized. They will rematerialize on the surface of a planet several hundred miles away nearly instantaneously.
Presumably the technology works as follows: a sophisticated computer scans the body of a person to be transported. The physical location of each and every atom is registered, and that pattern is stored in a computer. The computer then reassembles that person at a new location. How isn’t ever specified, as far as I know. One possibility is that the atoms, now disassembled from one another, are sent to the new location where the reassembly takes place. This would be akin to taking apart your bed when you move and then reassembling it at a new location, only on a much grander scale and with the extra little troubling detail that disassembling a human, unlike a bed, would normally be expected to kill it. The other possibility is that the atoms that once made up the traveler are discarded, and that the people are recreated using a new bunch of atoms at the new location. The latter method seems to be superior in explaining how the transfer can be instantaneous (you don’t move anything physically), but seems to be inferior from the perspective that it would be a bit awkward if the new location happened not to have the atoms you were looking for.
The difference between these mechanisms already provides an interesting thought experiment. Some of my students are very attached to their atoms. But from a materialist point of view, the great thing about atoms is that they are truly interchangeable. If you’ve seen one hydrogen atom, you’ve seen them all. I sometimes ask my students if they would drink water if they were living on the international space station, given that the only source of water there is water which has been recycled from the urine of astronauts. Most people have an aversion to this idea, but if the filters do their job properly, there’s no difference between the H2O coming from a natural spring on earth and the H2O emerging from the ISS recycler. This is especially obvious when you point out that the H2O coming from the natural spring has, itself, been untold number of horrible places before it tricked down into the crust of the earth.
Then, too, there is the rather obvious fact that “my atoms” are mine only by temporary arrangement. Skin cells slough off, hair falls out, sweat expires, carbon dioxide is exhaled, sodium, calcium, phosphorus, magnesium, potassium, and iron make there way through any number of internal body compartments before eventually being excreted from the body, to be replaced at lunch by different atoms. Atoms that were somebody else’s yesterday.
But this is only one aspect of the thought experiment. Whether you would prefer the same-atoms or the different-atoms mechanism is the minor problem. The major problem is: would you go at all?
Like Searle’s Chinese Room character, I take it as a given that, from the outside, all is well after transport. Just as it doesn’t matter to the people getting their questions answered by the Chinese Room if the man inside understands or not, it doesn’t matter to Starfleet what happened to the original Kirk or Spock or McCoy after they rematerialize. They behave exactly the way they always did, right down to completing a sentence they started before they dematerialized.
(Some students try to evade the question by expressing a fear that everything won’t be the same – that something could go wrong. This is cheating. Something often went wrong on Star Trek because it made for a heck of a plot device, but the point of a thought experiment is to analyze the results of something given certain conditions, and in this case, we are specifying that nothing goes wrong.)
(Some students also try to evade the question by missing the point entirely. The position and identity of atoms can be scanned by a computer, but things like memory and emotion can’t be. But that’s wrong. We have decades of data proving that memory and emotion are made by brains, and brains, we know, are made up of atoms. If memory and emotion depend on the arrangement of the atoms of a brain before transport, they depend on the arrangement of atoms in a brain after transport too.)
The question isn’t are Kirk and Spock and McCoy identical from the outside. In fact, I don’t even think the issue is whether they are identical on the inside. I believe that our subjective states are dependent on the brain too, and so whatever it was like to be Kirk before transport, it is still like that to be him after transport.
The issue is this: is it still the same Kirk? Have we transported Kirk? Or have we killed Kirk, and created a copy of Kirk identical in every physical – and every nonphysical – detail?
Perhaps the most disturbing version of this thought experiment is to point out that the information about the arrangement of Kirk’s atoms is still in the computer. I don’t think this was ever really dealt with in any of the Star Trek series. That is, there were times when rematerialization failed to take place instantaneously, but the characters were eventually recreated because the information was still in the computer. Fine. But what prevents that information being used to create a second Kirk? I suppose this is only possible if you can use any old atoms (not just the ones you started with), so let’s say that’s what happens.
Put it this way. The computer is powerful enough to scan 6 people at once and rematerialize those people hundreds of miles away. Why not then scan just one person, but create 6 copies of that person, each rematerializing a few yards from one another? Created at the same time from the same pattern, the 6 people would be, at least at that very moment, 6 physically and mentally identical people. From that point there would be differences created, but at that first moment, there would be no differences.
It seems to me that if this is possible (possible, that is, in the context of a thought experiment), it is senseless to ask which one of the 6 is the real Kirk. The only conclusion would be that the real Kirk ceased to exist when he was dematerialized. If there is no real Kirk anymore when 6 copies have been transported, then it seems to me that there is also no real Kirk anymore even in the standard case, when there is only one.
Which, it seems to me, leads to yet another problem. What was the real Kirk in the first place? Was the real Kirk the information stored in the computer? Is that what we are – information? Or was the real Kirk only that being which was biological and intact and whose substance can be traced back unbroken to the time of his conception?
But wait – isn’t that another problem? Even though I’ve just talked myself out of believing that the pre-transport Kirk and the post-transport Kirk are the same being, on almost every measure these two Kirks are far more similar to each other than is the Kirk right before the moment of his first-ever transport (say at age 20 at Starfleet Academy) and the 10-year old Kirk helping his dad on an Iowa farm. In the first case, you have two brains identical in every respect, in the second, you have a 10-year old brain and a 20-year old brain which share a history and virtually nothing else.
I would say this is giving me a headache, except that I’m rather at loss to explain how this ineffable, subjective head-hurt could ever have come to be.