Reductionism does not succeed even for simple physical phenomena

Here is a great anti-reductionist paper, in which the author demonstrates that:

* Temperature is not equivalent to the particular mean molecular kinetic energy of a collection of molecules, since any collection will always have such a mean but it still may not have a temperature:

“The appearance of the temperature as an argument in the Boltzmann distribution function
ni = n0e-Ui/kT
is therefore precisely what it seems to be, a macroscopic determinant of a microscopic condition without which a gas does not have a temperature.”

* Water is only a collection of H2O molecules in its gas phase. Even the purest of liquid water will contain many hydrogen and hydroxyl ions. So even such a simple substance as water does not reduce to H2O.

The situation is worse with more complex molecules:

"For example, methyl ether and ethanol share a Hamiltonian, the quantum mechanical description of their energetic properties. Nevertheless, they are very different molecules. Ethanol is extremely soluble in water, whereas dimethyl ether is only partially soluble in water. Ethanol boils at 78.4°C, while dimethyl ether boils at 34.6°C. Drinking ethanol leads to intoxication, while drinking dimethyl ether has no such effect. Given that quantum mechanics cannot tell us why a given collection of atoms will adopt one molecular structure (and set of chemical properties) or the other, Hendry argues that chemical properties cannot be recovered from quantum mechanical properties (1998, 2006b, 2010a)."

There are still reductionists who argue that chemistry in principle could be reduced to quantum mechanics. But if someone tells you the chemistry has been reduced to quantum mechanics, they have no idea what they are talking about.

2 comments:

  1. It took me several days to figure out what that part about dimethyl ether and ethanol meant.

    Once I did, I realized he makes a good point, but it seems a very strange way to say it (i.e., that the Schrodinger equation cannot tell you what compound will form from the various particles which go into the equation because there are multiple metastable configurations which are legitimate 'solutions' to the equation.) Seems like there would be a more straightforward way to say that -- like maybe what I just said. 'Sharing a Hamiltonian' seems very obtuse to me.

    Seems like a really interesting topic, but I couldn't bring myself to read that whole thing. I feel like someone is drilling into my head very slowly with a corkscrew when I read something like that. Chemistry is supposed to be fun and exciting, not painful. Personally, I will always fall back on the notion that abstraction = simplification, which seems so incredibly simple and irrefutable to me. Once you see that, all this other stuff immediately seems so obviously silly.

    Reality => abstraction => mathematical expression

    Given that everything to the right of the first arrow is intrinsically 'not reality,' (in that A != not A, or whatever) and further that it encompasses science (I could have substituted 'science' for abstraction) it should be immediately clear that reductionism is wrong -- science can never quite describe reality just because it isn't reality, if for no other reason. Science is a special sort of make-believe, with special rules. Like mythology, or a good novel, or a painting, maybe -- a make-believe for the purpose of expressing truth.

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    1. "Given that everything to the right of the first arrow is intrinsically 'not reality,' (in that A != not A, or whatever) and further that it encompasses science (I could have substituted 'science' for abstraction) it should be immediately clear that reductionism is wrong..."

      Well put, Scott.

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