Saturday, February 14, 2015

Define. Clarify. Repeat.

Being A New Post for Marco to Hook Comments On

Like most people with an interest in the historical sciences, Alfred Wegener is one of my heroes. He marshalled an overwhelmingly convincing mass of evidence of the need for continental drift, argued his case coherently and courageously against monolithic opposition, and was eventually vindicated long after he disappeared on a macho scientific expedition across the Greenland ice cap.

Like most people who have thought about it seriously, the pillars of the scientific establishment who mocked Alfred Wegener are also my heroes. Because no matter how much evidence there is of the need for a new theory, you can’t throw out the old theory until you have a new theory. And for a new theory to be science, it needs to have a plausible mechanism. And in the case of continental drift, there was no proposal for how it could possibly have happened that was not obviously wrong until the mid-ocean ridges were discovered, long after Wegener’s death.

To generalise: if you are an iconoclast who wants to convince me to change my mind about something scientific, you need to do two things. (1) Present an overwhelming mass of evidence that the existing models are inadequate: there has to be something that needs to be explained. (2) Present some vaguely plausible model, consistent with the other things we know, that explains this stuff that needs to be explained.

 The rest of this post is just going to be me arguing with Marco, so I’ll see the rest of you later. :)

From the most recent comment of Marco down on the ‘Yes,  Natural Selection on Random Mutations is Sufficient’ post:

I'm just going to summarise what I believe to be the source of our differences.

It does not make sense to talk about the source of our differences. You have not yet clarified your model sufficiently for it to be meaningful to talk about the differences between us. As the iconoclast, you need to present overwhelming evidence that the existing model needs to be changed, and some plausible mechanism for an alternative model. These are both necessary. Reiterating that you see the need for a change, and advancing very vague mechanisms that are not linked to the known facts of molecular biology, are never going to convince me. Of course there is no need for you to convince me; but if you want to convince anyone in the scientific community, these are the two things that you need to do. 

1) Experimental basis - your mentioning that a synthesis cannot be experimentally derived by definition, is to me an admission that it is not strictly science. You do believe it to be science by a reasoning I do not accept.

The only way I can construe this statement is that the historical sciences in toto are not science. To me, this is an unreasonable limitation of the meaning of ‘science’. It impacts all possible mechanisms of evolution.

2) expanding informatics principles to genetics - genes as a store of information and instructions analogous to a computer algorithm. To me it is obvious and valid - to you (and biologists in general) it is a big no-no.

This is because biologists know more than you do. The relationship of genes to computer algorithms is only an analogy, and it is a very weak analogy.

3) definition of randomness - Ditching a statistically valid definition of random in favour of a statutory functional one makes the synthesis *not falsifiable* in the statistical sense. One should be able to verify that a simulation based on statistical randomness would come to the same probability distribution.
4) Dismissal of trivial non-randomness. You appear to do this equally for biochemical reasons that mutations would happen in certain areas more than others that are not proportional in any way to the function, but also it appears for things like horizontal gene transfer and epigenetics effects. To me it is an admission that random is incorrect even in your functional description. For instance, I think it is as reasonable a synthesis that horizontal gene transfer explains the spread of all beneficial mutations. I do not think that it is the whole story, but the standard evolutionary synthesis crowds out other ideas as if it had been experimentally verified.

I am absolutely sure that a simulation based on statistical randomness  could show natural selection on random variations was sufficient to account for biological change. I am absolutely sure that a simulation based on trival non-randomness could show natural selection on what I call trivially non-random variations was sufficient to account for biological change. Alternatively, I am sure that a simulation based on statistical randomness could show natural selection on random variations was not sufficient to account for biological change. None of these simulations would necessarily tell us anything about reality. The real system that we are trying to simulate is too complicated. Modelling is not experiment. All models are only as good as their assumptions. This quibbling about definitions of randomness is, to me, irrelevant and uninteresting. It does not get us one step closer towards identifying a deficiency in the standard model, nor clarifying a plausible mechanism for directed evolution.