The Reductionist fallacy

Ard: I remember when I first learned basic statistical mechanics and how to calculate ideal gas law from the interaction between the atoms, and then I began to calculate more complicated gas laws and then equations of states. It’s a very powerful and beautiful thing.

GE: Yeah, it’s beautiful.

Ard: And so it’s not so surprising, sometimes, that if you’ve had that experience, you think this is the best way of understanding the world.

GE: Yeah. And in my view, the scientifically legitimate thing is to try and extend that as far as you can, so you can see the widest domain that you can explain by it. The problem comes if you try to say this is the only thing which is happening; it’s the only kind of causation that is possible. That’s where the problem comes.

And so I have this definition of a fundamentalist. My definition of a fundamentalist is someone who takes a partial truth and claims it’s the total truth, and that’s exactly the problem here.

If you say that statistical physics explains a lot of stuff, there’s absolutely no problem. If you claim it explains everything, including life, it’s simply not true. And I think a lot of the problem here is that the people who are wanting to say that all we’ve got is the bottom-up causation... they are just… one should pursue bottom-up causation as far as one can, and it’s very powerful, but it’s not the only thing in existence.

In fact I make quite a strong claim there. If you want to create life, there’s a level, a ceiling that you can reach by bottom-up assembly of molecules and so on, and you can’t get any further for one very simple reason: after a certain time, adaptive selection has to come and you’ve got to start adapting to your environment. Now when that happens, the environment has to feed in signals to this organism which will change either its structure, or its behaviour, or both.

Now, that’s top-down causation from the environment into the structure of the organism at the macro level in your organism and down to the electrons and protons in the organism. If that top-down causation does not come into existence, you can’t get life, and so I make a strong statement that purely bottom-up causation will not bring life into existence.

David: Ah, that’s very interesting. Because you are saying it feeds information in, and you have said that before: information is the new thing.

GE: Yeah, what’s DNA about?

David: Life is information: it’s coding. And information is a real thing, but it’s not physically real is it?

GE: No.

David: Because the information is different from the way that it’s encoded.

Ard: And the information is coming in from the environment.

David: That’s fantastic.

GE: The whole point of DNA, the wonderful discovery of DNA, is that it can, like a Turing machine, it can encode any protein structure you like, any one at all, and the physics doesn’t determine which comes out. So if you’re a tele-physicist, predict for me what the DNA sequence is going to be. You’ll shrug and say, ’I can’t do it’, because this ain’t physics, it’s biology. It’s a different logic, as it were.

David: So is that an emergent level then?

GE: Yes, absolutely. But why people believe in reductionism is the unbelievable success. And you experience it, as you were saying, with the kinetic theory of gases. It works absolutely beautifully. The atomic structure of matter has been a huge success. Then there was the physical structure of chemistry. The wonderful, wonderful discoveries of Linus Pauling and all these people of how chemical structure emerged, the quantum physics. Wonderful success.

Then there was the molecular biology revolution with Crick and Watson and so on, and life is molecules interacting with each other, and there’s this DNA coding and so on. Wonderful.

And then there was the whole thing of neurons and how you could understand the mechanism of the brain in terms of electronic impulses going down axons and dendrites according to laws which are perfectly understandable in terms of the underlying physics.

And so the reason people pursue it is because it’s been so incredibly successful in a most extraordinary kind of way. But, in each of these areas, there’s always been a counter-reductionist thing, like in the case of statistical physics. The arrow of time is still a worm at the bottom of the thing in the case of statistical physics. In the case of chemistry, chemistry is a success in principle but not in practice.

In the case of the genes there’s been the whole epigenetic thing coming back and saying causation is not only bottom up. Epigenetics is the solid statement there’s a mass of top-down causation. And in terms of the mind, you find you cannot understand the mind in bottom-up terms only.