Wednesday 14 March 2012

Is natural selection open-ended, or constrained by forms?


One key question about Natural Selection is the potential scope of change it may cause.

It is relatively uncontroversial that selection processes can change organism within their basic form - so that different breeds and sub-species of dogs, cats or sheep - with different appearances and functional characteristics - can be bred by selection.

And such selection could be human or natural, as when sheep which bred on Northern Hills for many generations will be hardier than those bred in Southern Valleys.

What is uncertain is whether Natural Selection can create new forms.


I know that it is assumed that Natural Selection can lead to new forms, but this is an assumption; especially so because there is no answer in modern biology as to where forms come from in the first place.


Once there are forms, then selection can potentially change them by selection, absorption and combination of forms (for example) - but evolutionary theory typically does not recognise forms as qualitatively distinct - yet it is the reality of form which is assumed whenever we assert that evolution by natural selection has occurred.

Such forms might be a species, or a functional organ such as the eye, or something which is regarded as homologous across evolutionary history - such as the human anterior pituitary gland having evolved (by many steps) from a chemo-sensitive 'nose' in primitive chordates.

Natural selection has to assume the reality of such forms before it can theorise about them evolving - therefore it lacks the basis for explaining how forms arise and in what order and how to identify forms.


On this basis, it seems that it may be coherent to use natural selection only as an explanation of modification within the scope of a form which has already been assumed - and to look elsewhere for explanations of the creation of qualitatively new forms.

So, the scope of natural selection is therefore restricted to suggested explanations for modification of existing forms.


Of course, this leaves open arguments about when a form is indeed novel: for example is the bird a qualitatively new form compared with the reptile or merely a quantitative modification?

Is the chimpanzee a new form compared with the amphibian or merely a quantitative modification?

Is the human a new form compared with the amoeba or merely a quantitative modification?

Is there just one species modified tens of millions of times (hence tens of millions of forms), or tens of millions of qualitatively distinct species, each with a different form?


Forms are therefore assumed, not explained, by Natural Selection; and selection ought no to be used to explain novel forms.




The Crow said...

I become ever more aware of the human desire to always know the why and how of things. Or to seek this information from others who may 'know' it.
Science is the main offender, here, if such a thing can be called an offense.

Imagine humans being able to detect what is in front of them, and dealing with it, as-is, without standing back from whatever it is and analyzing it, first.
It is probably very useful to be able to do this thing that humans do, but as a default way of operating?

There is madness, inherent, in this automatic analysis/judgment/disconnectedness. Only now are we witnessing the scale of this madness. Where once we may have found the idea of the 'Mad Scientist' amusing, now we have an entire society of Mad Scientists. See how well it works.

If you ever wondered what happened to Christianity, maybe there is your answer. Eat that apple and die a lingering death.

Thursday said...

One of the main complaints about ID is that it is god of the gaps thinking, which leaves room for future discoveries to fill those gaps, which they often do. This is a perfectly reasonable point to make, but you are right that it isn’t anything like proof.

The real problem with this kind of thinking is what it implies about God. John Derbyshire, back when he was a Christian, nailed it:

“ID is not just lousy science, but lousy religion. I dislike it at least
as much for religious as for scientific reasons. I dislike it, in fact, for
the same reasons, or at least the same KINDS of reasons, that I dislike the
“Left Behind” books & movies, and unbelievers telling me that natural
disasters like the recent tsunami “prove” the non-existence of God.
All that kind of thinking trivializes God. It belongs to the category of
thinking that A.N. Whitehead called “misplaced concreteness.” It shows a
dismal poverty of imagination — reducing the divine to science fiction (or
in the case of the “Left Behind” books, to a combination of sci-fi and spy
thriller). The ID-ers’ God is a sort of scientist himself, sticking his
finger in to make things work when natural laws — His laws! — can’t do the

“Their God is a science-fiction God, a high-I.Q. space alien plodding along a decade or two ahead of our understanding.”

The sort of theorizing about God always needing to intervene in the evolutionary process tends to turn God into a capricious and incompetent tinkerer, what with all the poor design we find in nature.

On a more general level, this illustrates the dangers of combining modern and pre-modern ways of thinking. Usually, you get ideas that have the worst of both worlds.

Bruce Charlton said...


Sorry, but I wondered what in my posting you focused on to make your comment on Intelligent Design. From my perspective the comment looks like a non sequitur - could you spell out the connection please?

(I'm not a proponent of ID, mostly because I regard this as a matter of metaphysics not biological evidence; but I could see how you might think I was from the posting.)

BTW are you the same blogger Thursday (The man who was) who used to comment on HBD blogs and write about arty matters (and I left a few comments on your blog). Or are you someone else?

Thursday said...

Same person. On Wordpress blogs and some other blogs I comment as The Man Who Was . . .

Doesn't ID include the idea that there couldn't be a transition from one species to another without special divine intervention? It certainly does include the idea that certain organs could not evolve from predecessors without special intervention, and, more generally, that the evolutionary process could not continue without special intervention.

I don't see how your thoughts here are different, but perhaps you could explain why they are.

Bruce Charlton said...

@ Thursday - Oh good, I'm glad you are the same person, because I had been assuming you were.

The main difference is as follows: as I understand ID, they are saying that certain specific instances cannot be explained by Natural Selection, therefore imply ID.

But I am saying that NS is a metaphysical assumption, therefore *everything* can be explained by NS simply because the prior assumption is that everything can be explained by NS; and if it can't yet be explained by NS then this will happen at some point in the future.

For example there is no good NS explanation for the existence of sexes, but most biologists *assume* that some adequate expanation will emerge in the future. The failure to explain the evolution of sexes is no challenge to NS.

No conceivable observation can challenge NS, because science cannot challenge metaphysics, metaphysics is above, prior to, science.

What I am saying, or asking, is that all the common sense obviosu evidence for natural selection is of a broadly 'within species' type - and all the evidence of between specieis evolution is based upon many layers or steps of scientific inference.

How do we know that scientific inference is correct? We don't - except in so far as we trust scientists to be truth seekers and truth speakers as well as dedicated to studing problems - and insofar as scientists will link their theories to common sense and common experience - so they can be tested by such means.

But do we trust scientists? Are they trying to do this linking?

No and no.

Al. said...

No conceivable observation can challenge NS [...]

Dr Charlton, how do you view Sir Karl Popper's recantation of his initial negative stance on general evolutionary theory in the framework of science and his later change of mind that natural selection is indeed falsifiable ? I'm sorry if this is obvious in this context ...

Bruce Charlton said...

@Al. - I don't know - I'm too busy trying to work out my own position without worrying about KP! I'm not even sure whether KP understood Natural selection as deeply as I did (obviously others understood NS more deeply than I did, but I was pretty deep into it, thought about it a lot for several years!)

Al. said...

Hm ... this is a topic I happened to exchange lengthly emails on with an "atheist" friend in the past few days. What might be interesting to consider is the proverbial precambrian rabbit ( as well the criteria that Darwin himself put up under which he would regard his theories falsified (like "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down."), although I'm no sure how helpful they are outside the original science setting. I find it very difficult to have a opinion on the classification of Natural Selection myself. Even going back to the writings of KP did not prove as fruitful as it had previously appeared since the context of his research changed quite a bit over the years.

Thursday said...

I see how you get to where you are through a more philosphical method than the IDers, but you seem to end up in a similar place. Since common descent does have a lot of evidence behind it, the only plausible way to get from one species to another or one organ to another would seem to be natural selection or else direct divine intervention. And the latter still suffers from the theological problems outlined by Derbyshire.

Bruce Charlton said...


I would say, from working in the field, that Natural Selection cannot be falsified: it is an assumption...

but...@Thursday - this is not specific to Natural Selection. NS is just a typical science in this respect.

My belief is that real science must be anchored to common experience as interpreted by common sense - otherwise it stops being science (for example, modern medical research, which includes its own evaluation criteria and rules out the validity of individual experience).

So, science is (ought to be) validated in terms of obvious differences it makes in the real world. The technical, professional science needs to be linked firmly to these obvious differences.

NS is linked to a few obvious differences, but mainly serves as a professional research program by unifying biology (but the professional structure must ultimately be linked back to common sense evaluations, which isn't happening) - AND as a philosophy, but a very bad philosophy.

NS as a philosophy is not refutable, but as such it is arbitrary, and from a Christian perspective it is intrinsically evil because it excludes all Good/s.