a guest post by Regina Rini
There is, undeniably, such a thing as a science of consciousness. People use brain scanners and clever experimental techniques to figure out the neural processes correlated with conscious experience. I don’t wish to challenge the value of this research. However, I think there is something odd about consciousness as a scientific subject, something I’ll call the privileged sample problem. If I’m right, then consciousness is importantly unlike anything else science claims to study.
To see the problem, imagine this: you are one of the world’s pre-eminent neuroscientists. You know as much about the cutting-edge science of consciousness as anyone else. Unfortunately, you are in a car crash and suffer serious head injury. For several weeks you are in a coma, but gradually you emerge into consciousness again. Unfortunately, you quickly realize that you have no control over any part of your body. You are an extreme victim of locked-in syndrome: though you are conscious and aware of your surroundings, you cannot move or speak or indicate your awareness to the outside world. (Unlike Jean-Dominique Bauby, the author of The Diving Bell and the Butterfly, you can’t even control your eyelids, so you can’t communicate by blinking.) As far as anyone else can tell, you are just as you were in coma: lying there in bed, eyes open and unfixed, unable to respond to anyone.
As it happens, your neuroscientist colleagues have been keeping vigil at your bedside. They are always arguing with each other, and of course they want to know whether you are conscious. Eventually they arrange to have your brain scanned, using the most sophisticated existing techniques for consciousness-detection. But the tests come back negative! And here’s the important part: when they gather around your bedside to discuss the data, you listen. You understand the science just as well as they do, and you realize that, given the data they have and the best existing scientific theory of consciousness, you agree that they are right to conclude that you are not conscious. If you were out there with them and had the same data, you’d think so too. But because you are in here, in your own mind, you know they are wrong. You are conscious. And so now you know that the best existing scientific theory of consciousness is wrong.
In this story, you are in a position to refute the best existing science based upon a single sample of the phenomenon being studied. This is not a normal feature of science. Science is inductive. Normally, if we discover a single sample which seems to defy our best scientific theory, we first check to see if we have made a mistake in measuring the sample. If we rule that out, we start looking for other samples that replicate the finding. If we can’t find any others – that is, if all other samples remain consistent with the best existing theory – then we will very likely conclude that the single inconsistent sample is a fluke. Our observation about the sample has gone wrong in some way, even if we can’t figure out exactly how it has gone wrong. What we will not do is overturn the best existing theory simply because it fails to cohere with a single sample.
But things are different when it comes to consciousness. Your own conscious experience is, for you, a privileged sample. It is reasonable for you to conclude that the best existing theory is false if the best existing theory predicts that you are not conscious. It doesn’t matter whether the best existing theory continues to correctly predict all other cases you know about - your own case is special. This is nothing other than Descartes’ famous point: your own consciousness is the last thing you can doubt. You are right to doubt anything else, including the best existing scientific theory, before you doubt that you are conscious.
Of course, your case is not special for anyone else. This is the other puzzling features of a privileged sample. You and only you have a certain type of access to this sample. Your grounds for employing it to refute the best existing theory are not publicly confirmable. Public confirmation is a cardinal feature of science, yet the science of consciousness is (in principle) constrained by observations that are not publicly confirmable. There exist possible observations that reasonably refute the best existing scientific theory on the basis of a single sample that is not available to public confirmation. That is the privileged sample problem.
What does the privileged sample problem imply about the nature of consciousness? Well, it doesn’t obviously imply anything radical about the ontology of the conscious mind. We can still be fully-committed physicalists even if we accept that there is something odd about the science of consciousness. But I think it does imply that we should be suspicious of any attempt to treat consciousness as a target of physicalist reduction. Really all I am doing here is find another way to express a point made by Thomas Nagel a long time ago: we have subjective and objective ways of thinking about our own minds, and one cannot be reduced to the other. We should not try to entirely replace conscious-subjectivity talk with physicalist-science talk, because the privileged sample problem shows that the science of consciousness is not a science like any other.
I got the idea for the privileged sample problem while formulating a question at the ‘Measuring Borderline States of Consciousness’ conference at NYU. Thanks in particular to Adrian Owen and Tim Bayne, whose fascinating talks on detecting consciousness provoked my question.
image credit: 'Sub Conscious' by Gregg Jaden