Friday, April 24, 2009

Can consciousness be explained by science? -I

Part I: Can the mind exist without matter?

In the first part of this two part blog entry I would try to argue that all our conscious activity must correspond to definite physical changes in the brain. In other words if neuroscience were to ever reach a stage such that all physical changes in the brain could be observed and monitored (a goal that may be practically unattainable) we should be able to tell what a person is seeing, hearing, feeling and thinking by simply observing her brain.

Neuroscience may be far from reaching such a stage but discoveries already made in the field strengthen the case for the above proposition.

In a 2002 study British neuroscientists asked subjects to look at photographs of real faces and objects. Using fMRI, a technique which uses MRI scans to locate active regions of the brain by detecting increased blood flow, they identified regions of the brain (see figure on the right) that are active when a person looks at a face (marked fg) and the regions which are active when he looks at an object (marked pg).

The subjects were then shown Rubin's famous Vase-Face illusion (see figure on left). By simply looking at which regions were active in the MRI scans the scientists could predict whether the subject was perceiving the image as two faces or as a vase!

You may be thinking that while discoveries like this (see V S Ramachandran's BBC Reith lectures for many other equally fascinating examples) are definitely suggestive, my initial proposition is still a big extrapolation if it is based only on such findings.

There is in fact a more fundamental reason for my belief, a reason that I have learnt to appreciate because of my training in physics. A physicist would view the brain and its functioning as an extremely complex natural process. Physicists have a simple approach when they try to understand complex natural phenomena. Just as any change in the picture on your computer screen is brought about by a change in the colour and intensity of each of the pixels, any process that we observe in nature is the result of a change of the arrangement of smaller particles like atoms that constitute everything. As there are billions and billions of them in even a small object, simply by moving from one place to another, these particles can accomplish wonderful things- the rusting of iron, the burning of paper, the discolouration of leaves in autumn, lightning, tornadoes, in short everything you see around you! All the complexity in natural phenomena is because of the large numbers of these particles involved in these processes (a screen can generate a far more complex picture if there are thousands of pixels instead of say twelve). The movement of these particles is governed by precise, empirically tested laws. Based on the present state of a system of particles these laws tell us how the system will evolve in time.

The functioning of our brain is undoubtedly more complex than the phenomena mentioned above but our bodies and brains are made of exactly the same atoms that physicists and chemists study in the lab everyday. How these atoms evolve with time is governed by the same laws. Therefore it follows that what we will do in the next moment depends on the physical behavior of the atoms in our brains at the present moment (which might correspond for example to a high level of activity or increased blood flow in a certain region of our brain or may be an unusually large number of neurons firing in another region). But we also know that what we will do in the next moment depends on what we are thinking and how we are feeling at the present moment- if you are angry you might yell at someone, if you are depressed you might call a friend etc. Consider the two italicized statements in this paragraph. As an effect cannot have two different causes these statements suggest that what we subjectively feel as an emotion like anger or sadness corresponds to a definite behavior of atoms, i.e. a definite physical process in the brain that can be, in principle, objectively observed.

So at the end of this part the partial answer to the question posed in the title seems to be that any mental activity must correspond to definite physical processes in our brain and these physical processes can be analyzed using the usual methods of science. I will argue in the next part of this post that a scientific description of the objective process that a thought, emotion or sensation is related to is, however, inadequate in capturing all aspects of our consciousness.

The concept of consciousness not tethered to a body is obviously meaningless from this point of view. Thus from this perspective the idea of ghosts or spirits or a soul that leaves the body after death is absurd! The same thing can be said about a nirakar (formless) God having conscious attributes like mercy and forgiveness. But then rules need not apply to God!


  1. I am a bit confused. Are you telling that every physical phenomena, however complex, can be described starting from the constituent atoms and their interactions? Or are you just trying to convey that complex phenomena can also be explained in some way or the other?

  2. I think you are missing the fact that even deterministic systems can be probabilistic. Isn't that what classical chaos is? So considering that you discuss something as complex as the human brain, I think its a fair assumption if I say the case in point is also probabilistic.

    So I don't really follow how you can assert your conclusions so firmly. Although your final reasoning discrediting claims of supernatural phenomena seems to be in order to me. The argument that conciousness is a physical realisation of a certain combination of physical processes is probably accurate, just as some computer programs actually show signs of "intelligence" from time to time but without the hardware that just wouldn't be realisable.

  3. @sourav, suvayu

    I do not think I am assuming that the laws need to be deterministic at any point. Let me rephrase my basic argument. The physical state of all the particles in our brain (which may be given by the product of all the individual wavefunctions in a quantum theory) has all the information we are allowed to have in order know what might happen in the future. This information may not be accessible to us and it does not completely determine everything about the future (may be we can extract only probabilities) but I think you will agree that this information places a limit on what we can know about the future from the present. Thus if, as it seems, our present thoughts and feelings also have information about what we might do in the future, this information has to be present in the combined state of the particles. This seems to suggest that our thoughts and feelings must correspond to some physical process.

    I am not suggesting that it is practically possible for anyone else to actually extract this information. I am also not suggesting that this is how we should try to understand brain function as studying what neurons are doing may be much more useful than studying what each and every proton, neutron and electron is doing.


    I think what you are saying is that it is practically impossible to do such an analysis most of the time which I of course accept, but I never assumed in my argument that it is.

  4. I would like to raise a question: According to you, all the information for the time evolution of each of the physical units is obtainable at any point of time. Thus, the complete exhaustive set of all possible paths is available, though it is probabilistic which one it actually follows.

    Now suppose,there is an external event. Say,a Bomb explodes, the news of which you hear on TV. How do you suppose this additional information (through what physical medium, interact with our basis (the physical composition of our brains)???

    As in the point I am trying to make is that,to interact with matter, you need some physical medium. How is information, traveling in the form of EM waves of a definite frequency(coming from the TV) have a specific interaction with our basis? How is it that, the same frequency EM wave showing a Sports channel not cause the same pattern change in our basis? How is it possible that this sort of abstract information is coded in matter???

    Since, all the possible probabilistic paths are available to us, you would definitely need some interaction to change that. Say, it was a first of a kind event. Of which, humans have no knowledge. Thus the information could not have been there already in our basis. Thus, do you mean to say that in spite of something extraordinary happening, we will all not react in the same way because the information is not pre-coded in our brain basis???

  5. @ dip

    First of all I think it was a bit misleading for me to say that the present physical state of our brain or our present mental state has all the information we are allowed to have about what we do in the future. What happens around us will obviously affect us too at some later time. So may be I should replace 'future' by 'the next moment' everywhere (I already made that correction in the post but could not change the my comment above).

    I really do not know much about how information about external events influences the brain, for example how an image we see is interpreted by the brain and how it is then stored in our memory etc. I am sure there are neuroscientists who know much more than I do but even they probably do not know a lot of things about how the brain works.

    Are you suggesting that it is not possible to have a physical mechanism to process all this information? I do not see why that should be the case. We cannot make computers that can recognize images today but there is no reason why we will never be able to do so or why it is in principle impossible to do so.

    Now let me try my best to answer your last question. For a new born baby everything that it sees or hears is new. But the baby learns to recognize things and react to new situations etc. I think I read somewhere that we start with a few basic instincts and acquire other instincts by association but again I am sure there are experts who know a lot more. I think your main concern is- how is it possible for us to learn new things and to learn from experience if we are just machines programmed to react to a finite number of "pre-coded" situations? Suvayu probably knows much more about this than we do but I think we already have softwares and programs that can "learn". Our learning of things is of course far more sophisticated than what these programs do but I mention these only to show that, although it may seem so, it is not logically incosistent to have machines which can learn.

  6. Yes, at a macro, human level, it is fairly easy to comprehend association, learning etc. But given,that the physical basis in us, itself is changing every minute, with newer atoms joining every moment, it is very hard to conceive the basis storing the information.

    However, the point of the question was, how do you suppose, 'news' as humanly perceived, causes a change in the pattern? How, is it possible for similar frequency, EM and sound waves, to interact and change the pattern in different ways???

  7. @dip

    When we see anything whether it is a TV screen or something else the light entering our eyes carries the information about the distance, color, brightness of the various objects (or in this case the various points on the screen) in our field of vision. For two different pictures the information carried is of course very different. Even a video camera can record this information. I do not see how the original transmission frequency of the TV waves is of any relevance.

    As I said earlier I do not know much about how this information is processed in the brain but you can have a look at this link.