On the impossibility of explaining chemistry by physics, and the even greater impossibility of explaining consciousness by physicality

Wavefunction has a great post on this subject.  Here's the link: http://wavefunction.fieldofscience.com/2011/02/difference-between-chemistry-and.html

Here’s a particularly fine passage of his on the subject:

“An example more familiar to chemists which is stated by Hoffmann also vividly illustrates the problem with reducing chemistry to physics. Consider the carbonyl functional group, a workhorse of chemistry. The most important reaction that this group undergoes is nucleophilic addition. How does physics explain this process? By essentially pitching electrostatics. Physics will tell us that the carbonyl carbon has a partial positive charge and the oxygen has a partial negative one, thus attracting nucleophiles to the carbon. But a chemist would find this simple explanation deeply unsatisfying. There is much complexity associated with addition to carbonyls which goes beyond merely electrostatic attraction. There’s the angle of attack of the nucleophile- the well-known Burgi-Dunitz trajectory- which maximizes orbital overlap. There’s coordination of positively charged counterions with the oxygen which can dictate the stereochemistry. There’s also the size of groups on the attacking nucleophile which can sharply tip the distribution of products through steric effects. Then there’s the gradation of reactivity of various nucleophiles based on their size and charge. And finally, there’s the all-pervasive solvent which can drastically change product ratios and stereochemistry through solvation effects.

Now note that the truly fundamental underlying basis for all these factors (and indeed, virtually everything in daily life) is the electromagnetic force, and so yes, physics can purport to actually ‘explain’ all these factors by saying that they are all mediated
through electromagnetism. Even steric effects are essentially electromagnetic in nature.”
In an earlier post –http://wavefunction.fieldofscience.com/2011/01/deepak-chopra-misrepresents-factsagain.html, Wavefunction essentially wastes his time preaching to the choir about Chopra, half truths, pseudoscience etc. etc.  He would have been driven crazy if he’d practiced medicine.  The world is full of people who love this sort of thing, and who in fact have a need to believe it. Can you say alternative medicine?  It is the doc’s remit to take care of these people when they get sick.  This entails not antagonizing them and attempting to keep them out of trouble, and then caring for them when it happens.  This means going in to the ER to care for a patient in status epilepticus who stopped her anticonvulsants because her chiropractor told her his manipulation of her neck had cured her.
Even more interesting are the comments on the Chopra post many of which involve the possibility or impossibility of finding a physical basis of consciousness.  Wavefunction seems to think we might be able to do this and refers his readers to Ramachandran’s work.  Some of the comments get fairly testy (which is why I blog anonymously).
Years of neurology in the ER, the ICU, the office rubs your nose in the fact that without a functioning brain you are not conscious. So physicality is a necessary condition of consciousness, but is it sufficient to explain it?  Well, perhaps if we had the entire wiring diagram of the brain — which neuron was connected to which neuron, we could.  We’d need a bit more than that, as we’d need to know what part of a neuron was being connected to (some neurons have over 10,000 connections from other neurons to them). Even that wouldn’t be enough, as most neurons are affected by neurotransmitters released generally into the brain — these happen to be the ones involved in mood (dopamine, norepinephrine, serotonin). Can you say psychopharmacology?
Even worse, it now appears that the connection diagram isn’t fixed like the connections between the transistors in a CPU, but is actively changing. Believe it or not, the technology now exists to watch this happening (e.g. new synapse formation) in the brain of an active behaving animal — for details see Nature vol. 462 pp. 859 – 861 ’09 (or better Neuron vol. 69 pp. 273 – 286 ’11). I’d have said you were smoking something if you told me this would be possible when I was starting out in neurology in the 60’s.
Certainly, the more we study the brain, the more we will know about it. We have a huge amount to learn about it.  Will we ever be able to explain consciousness on a physical basis?  As Clinton would say, “that depends on what you mean by explain”.  My guess is that we will not and the best argument that we won’t is (perhaps unintentionally) given by Wavefunction in the long quotation which starts this post.  The laws of electromagnetism are absolutely solid, and have been used to predict a variety of phenomena (remember Hertz predicted radio waves using nothing more than Maxwell’s equations).
We are still figuring out how neurons work and how they are affected by other neurons.  To go from this level of explanation (which we don’t have yet) to consciousness is a far greater jump than from electromagnetism to chemistry.
There’s a lot more to say about what constitutes an explanation at a given level, and the various levels at which phenomena arise, but that’s for another post (or posts).
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  • Wavefunction  On February 14, 2011 at 7:16 pm

    Usually I would not bother with people like Chopra. But one has to vent sometime, especially when every statement appears so dense with fallacies…

    I don’t know if we can ultimately explain the brain on a physical or chemical level. But there do seem to be tantalizing clues; functional selectivity which I wrote about before seems to promise striking insights into the causative interaction between simple ligands and complex behavioral responses. But yes, reductionism will get us only so far.

    The future is upon us.

  • Wavefunction  On February 14, 2011 at 7:17 pm

    Thanks for the plug

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