Darwinism not testable

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Popper's claim:

Popper said:
I now wish to give some reasons why I regard Darwinism as metaphysical, and as a research programme.

It is metaphysical because it is not testable. One might think that it is. It seems to assert that, if ever on some planet we find life which satisfies conditions (a) [i.e. Heredity] and (b) [i.e. Variation], then (c) [i.e. Natural Selection] will come into play and bring about in time a rich variety of distinct forms. Darwinism, however, does not assert as much as this. For assume that we find life on Mars consisting of exactly three species of bacteria with a genetic outfit similar to that of terrestial species. Is Darwinism refuted? By no means. We shall say that these three species were the only forms among the many mutants which were sufficiently well adjusted to survive. And we shall say the same if there is only one species (or none). Thus Darwinism does not really predict the evolution of variety. It therefore cannot really explain it. At best, it can predict the evolution of variety under "favourable conditions". But it is hardly possible to describe in general terms what favourable conditions are - except that, in their presence, a variety of forms will emerge.

Any thoughts?
 

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Tsunami said:
Any thoughts?
He recanted that position a few years later:

...I have changed my mind about the testability and the logical status of the theory of natural selection; and I am glad to have an opportunity to make a recantation.

Popper, K.R., 1987. Natural selection and the emergence of mind. Dialectica 32: 339—355.
 
  • #3
russ_watters
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My reaction to Popper's complaint (prior to the recanting) is a big "so what?" So what if it has a domain of applicability that is limited to the specific conditions of Earth? That doesn't make it any less of a theory.

There is a lot about the universe that we don't know, but the fact that we don't know everything doesn't mean we don't know anything.
 
  • #4
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Tsunami said:
Popper's claim:

Originally Posted by Popper
I now wish to give some reasons why I regard Darwinism as metaphysical, and as a research programme.

It is metaphysical because it is not testable. One might think that it is. It seems to assert that, if ever on some planet we find life which satisfies conditions (a) [i.e. Heredity] and (b) [i.e. Variation], then (c) [i.e. Natural Selection] will come into play and bring about in time a rich variety of distinct forms. Darwinism, however, does not assert as much as this. For assume that we find life on Mars consisting of exactly three species of bacteria with a genetic outfit similar to that of terrestial species. Is Darwinism refuted? By no means. We shall say that these three species were the only forms among the many mutants which were sufficiently well adjusted to survive. And we shall say the same if there is only one species (or none). Thus Darwinism does not really predict the evolution of variety. It therefore cannot really explain it. At best, it can predict the evolution of variety under "favourable conditions". But it is hardly possible to describe in general terms what favourable conditions are - except that, in their presence, a variety of forms will emerge.

Any thoughts?
At best, it can predict the evolution of variety under "favourable conditions". But it is hardly possible to describe in general terms what favourable conditions are - except that, in their presence, a variety of forms will emerge.
Favourable conditions can not choose but a program might get it right. Crick in the 70's had a theory that the Earth was intentionally infected.
 
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russ_watters said:
My reaction to Popper's complaint (prior to the recanting) is a big "so what?" So what if it has a domain of applicability that is limited to the specific conditions of Earth? That doesn't make it any less of a theory.

There is a lot about the universe that we don't know, but the fact that we don't know everything doesn't mean we don't know anything.
Actually, I took his statement to mean that we can ad hoc incorporate everything in Darwinism. Whether there are three species or one species on Mars, it doesn't shake Darwinism; Darwinism can even explain why there are two species which live in symbiosis.

wave,

can you by any chance elaborate on Popper's new position? I wonder what made him change his mind..
 
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Tsunami said:
Actually, I took his statement to mean that we can ad hoc incorporate everything in Darwinism. Whether there are three species or one species on Mars, it doesn't shake Darwinism; Darwinism can even explain why there are two species which live in symbiosis.
I think this view illustrates Feyeabend's criticism of popperism, that it is not really possible to hold all the implications of a theory in our head and therefore to rationally come up with meaningful counterexamples. So Feyerabend says Popper's criterion is an unacceptable idealization.

Why is prediction of number of species considered a critical case for evolution? We have not yet penetrated to the fundamental core of the relationship between existing species. It has just recently been proposed for example that the nucleus of the eukaryiotic cell may have originated as a DNA virus absorbed as an organel.
 
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Ok, Feyerabend's critique makes sense. However, it would be nice to get something of a criterion.

I mean, it should be possible to distinguish between theories like most in physics, and a theory like evolution. Or am I wrong in thinking there is something different here?

When Popper says that evolution is not a typical scientific theory, but more like a metaphysical theory, a research programme, especially that final part of the statement makes sense to me. Evolution seems to be something that works when you link it to an hypothesis about some concrete life situation.

Maybe this is just an emotional response, and I should regard evolution theory as no more metaphysical than the basis equations of fluid dynamics (which also are 'something that works' linked to an hypothesis of the present conditions).

However, I can't get the idea of a loose end difference dangling somewhere out of my head.
 
  • #8
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Tsunami said:
wave,

can you by any chance elaborate on Popper's new position? I wonder what made him change his mind..
Popper thought neo-Darwinism was a tautology and hence "not a testable scientific theory". For example, "survival of the fittest" is a tautology if we define "the fittest" to mean "those who survive". It is not testable and it has no explanatory power whatsoever.

His argument is flawed because scientists routinely make testable/falsifiable hypothesis about natural selection. For example, we can predict which phenotypes are most likely to be advantageous in a given environment. We can predict how allele frequencies vary in a population over time. Popper changed his mind when he realized that Darwinism is "difficult to test", and not unlike some theories in physics and astronomy.
 
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Another interesting point is the debate between creationists and natural evolutionists. What makes a magic assignment of the creation by a god more or less miraculous or incredible then a sequence of causes and effects that lead to the same result ? They can both be seen as totally miraculous and incredible or normal everyday phenomena. The reason why a magic assignment by a god seems so incredible is simply because we are not used to seeing it everyday. It is something too rare for our mind, it is something we are not used to experiencing or that is too far outside the way our mind decodes reality. But then for the creationists, the fact that matter can evolve automatically into a human seems just as incredible, it is something they are not used to experiencing etc.

So both explanations at a deeper level are equivalent, only that the creationist finds self evolving matter too impossible to be true and the scientist finds magic assignments too impossible to be true. It is more a debate on aesthetics, more on how things look, are they pretty or ugly, incredible or boring, etc. If we lived at the quantum size level, particles would pop in and out of existence every moment, we could easily accept magic assignments, or if we lived in a computer simulation where very complex things just appeared and dissapeared without cause and effect, we would easily embrace creationism. What is incredible and what isn't ?
 
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