Wednesday, January 19, 2005

Cells and Sympathy

Charles Hartshorne espoused the view that our cells and our conscious selves feel each other through sympathy. For example, here is a quote from this article:

"Take the case of pain. We have this feeling if certain cells of ours undergo damage. But if the cells have their own feelings, they can hardly enjoy being damaged. So what is our suffering but our participating in their suffering? Hurt certain of my cells and you hurt me."



This view has a lot of intuitive appeal. However, when the physiology of sensation is investigated in more detail, the situation becomes complicated. The experience of a sensation is largely dependent on what area of the brain the nerve fibres (connected to the receptor cells which received the stimulus) go to. For example, the burning, crushing or bending of a pain nerve receptor cell will give rise to the sensation of pain. Similarly, the burning, crushing or bending of a touch nerve receptor cell will give rise to the sensation of touch (not pain). Thus, the experience of the conscious subject may not be "in sympathy" with that of the original cell.

The broader issue here is how what is consciously felt in our subjective experience relates to the feelings of bodily cells and, by extension, aspects of the world external to the body. That is, how are the affects of the body and world correlated with those that humans experience by virtue of the brain?

To exemplify the issue in more aesthetic terms - is the feeling of beauty aroused by looking at a flower or a sunset produced solely by the brain - or do aspects of the flower, the sunset and the sensory organs also partake, in some form or another, in the beauty that is experienced.

For me to explore this issue in full adequacy, my knowledge of the physiology of sensation needs to be further developed. Nevertheless, at this stage I see four possibilities (on the assumption that panexperientialism is true) in relation to how the feelings of our sense receptor cells relate to what is consciously felt:

1). The brain amplifies or attenuates the feelings of the receptor cells.

Thus, while a touch receptor cell may ‘feel’ pain on being crushed, the architecture of the brain and the various neural pathways through which the nerve impulse travels from the receptor cells results in the attenuation of this feeling, so that the person experiences only the sensation of touch. However, the neural architecture means that the crushing of a pain receptor cell leads to amplification of the feelings of pain experienced by the receptor cells, resulting in the person experiencing a sensation of pain. Alternatively, the sensory receptors themselves may only be capable of a limited range of feelings (such as touch or pain), which are then transmitted to the brain for amplification or attenuation.

Note that in this scenario, the nerve impulses transmitted from different receptor cells may be associated with or transmit different feelings, although to the scientific observer there may not be any measurable differences between them.

2). The transmission of some feelings through the body occurs through nonsensory means.

This possibility correlates to some extent with Whitehead’s description of “perception in the mode of causal efficacy”. In this mode of perception, the feelings of bodily cells which contribute to the feelings of the person are not transmitted solely by the nervous and sensory systems, but are also transmitted through the body by direct feeling (in ways in which contemporary science does not recognise).

Thus, in this scenario what is felt by the bodily cells may be correlated with our subjective experience through being felt by nonsensory means. This would also account for parapsychological phenomena (if indeed there are such phenomena). In the case of the damage of a touch receptor cell giving rise to the sensation of touch, it can be deduced that this nonsensory transmission of feelings is not significant. However, other aspects of subjective feeling (for example, the experience of hunger, fatigue, nausea, excitement, fear), may be more significantly correlated with nonsensory transmission.

3). The feelings of bodily cells are re-presented by the brain.

Under this scenario, the actual feelings of receptor cells have no direct relation to what the person feels. Rather, the transmission of nerve impulses and the architecture of the brain “recreates” the feelings felt by the receptor cells. This is similar to representationalist theories of perception, whereby the brain represents data received from the external world to create an image of the external world which is subjectively experienced (for a lucid and easy to read explanation of representationalism click here).

Note that if the bodily feelings we experience are a result of representation by the brain, there is no a priori reason why our subjective feelings would be correlated with what is felt by our receptor cells. Rather, this correlation can be explained on evolutionary grounds. For example, if an animal’s cells are experiencing pain because they are being damaged, it is obviously of survival value for the conscious animal to also experience pain, so that that stimulus of the pain can be avoided. However, it may not necessarily always be evolutionary advantageous for feelings to be represented by the brain in the form in which they are originally experienced by parts of the body.

4). Feelings and sensations are solely produced by the brain.

This option follows from option 3 - If the feelings of the bodily cells are not directly relevant to what is felt by the person then there is no real need to assume that feelings exist anywhere other than when they are produced by the brain. Thus, under this scenario when the receptor cells of the body are damaged, they do not feel anything. It is only the coordination of nervous impulses by the brain that gives rise to sensation. Away from the brain, there is no sentience or feeling.

This option is a somewhat depressing prospect and brings to mind Whitehead’s lament that under this view “the poets are entirely mistaken. They should address their lyrics to themselves, and should turn them into odes of self-congratulation on the excellency of the human mind. Nature is a dull affair, soundless, scentless, colourless, merely the hurrying of material, endlessly, meaninglessly.”

Two factors which count against this option are firstly, if feeling is not ubiquitous in nature and the panexperiential ‘stuff’ has not relation to it, the question arises as to how feeling and sensation is generated by the brain. This is analogous to the problem of the ‘magical emergence’ of sentient properties from the insentient matter of the brain which plagues many forms of materialism (although it is less problematic to get from some form of panexperiential material to feeling and sensation then to get from totally inert matter to the same). Secondly, if the panexperiential material has no relation to feeling or sentience, it is difficult to conceive what it might consist of.

Conclusion

At present I have an open mind on this issue, but favour some sort of combination of options 1 to 3.

These three options are not mutually exclusive and the predominance of each mode in a particular organism could be explained in evolutionary terms. For instance, in prebiotic and unicellular organisms the direct mode of perception (option 2) would be the sole or dominant mode. As the nervous system developed in more complex organisms attenuation and amplification of feelings (option 1) may have concurrently evolved. Finally, in organisms with reasonably sophisticated brains, feelings and affects of the body may often be entirely represented to the perceiving subject through the brain (option 3).

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