Dr Adequate
Banned
- Joined
- Aug 31, 2004
- Messages
- 17,766
Some people have said recently things along the lines of "We know that evolution took place, but need it have been Dawinian" --- offering up "Intelligent Design", as an alternative.
One interesting point to note is that this line of reasoning would make the story of evolution absolutely impregnable. The YEC may ask "What use is half a wing?" and the Darwinian is obliged to answer. The proponent of guided evolution can just say: "Goddidit".
This is by the by. Let's look now at the Darwinian point of view, and see if it could have any holes in it.
To summarize, Darwin accounts for the origin of species "from a few forms or one", as he says, by a process of inheritance, random mutation affecting the genotype and natural selection acting on the phenotype. Of course, Darwin did not know the laws of genetics, and we do: instead of "random mutation" he would have just said "variation" without postulating a mechanism.
I hae already reviewed the evidence that Darwin's mechanism is indeed successful in problem solving. But of course we know of two mechanisms for problem solving --- Darwin's or intelligent design. Which should we suppose accounts for the origin of species?
Well, let's review the three planks of the theory. First off, inheritance: I don't think there's any squabble about intelligence.
Second, random mutation. Now, you might wonder whether mutations are random or directed. For example, it would be possible before the invention of modern genetics to suppose that the devlopmental pathway of a creature and its decendants where all programmed out in advance, so that evolution would really be an "unfolding" of the story told in the genes. This would also have been proof of intelligent design.
But we know now that this is not the case. Indeed, not only hasn't this happenned, but it wouldn't work --- there would be no selective pressure on the genes due to be expessed in the future and so nothing to keep them from degrading.
Then again, we might once have dreamed of Lamarckian inheritance, where acquired adaptive traits are inherited. But again, genetics tells us that this cannot be --- information doesn't pass from the phenotype to the geneotype.
Indeed, there be no way in nature for a gene to "better itself". To do that, it would have to "know" whether it would be a good idea to mutate a C to an A, or whether this would be neutral, or disasterous, at that particular location. But there is no way in nature to get from a genotype to a phenotype --- except by expressing the phenotype.
Similarly, we know the external causes of mutation. In order for them to be non-random, a dumb chemical or radioactive particle would have to aim itself at the place where it would do most good to the descendants of the animal it's tagetting.
Finally, observation does in fact tell us that mutations seem to be non-directed and purposeless.
I conclude: mutations are, in nature, random. Now you may well point out that I have not ruled out divine intervention (or, if you will, ETs with technology in advance of our own) and wasn't that what I was trying to do? I'll return to this point. But first, let's look at natural selection.
Can any other natural force act on the phenotype but natural selection? No: by definition. You might as well ask a physicist: "Couldn't there be some other force acting on the body you're talking about besides the net force acting on the body"? No, that would be part of the net force. The pressure of natural selction is the sum of the selective pressures on the phenotype. Anything which isn't natural selection is artificial selection or unnatural selection.
This leaves us, again, either with Darwin to account for evolution, or some mysterious intervention --- God, aliens, what have you. We may note that such intervention, running as it does counter to natural selection, would make the affected animals less fitted to their environment that would be the case if there wasn't any such tampering.
We seem, then, to have reduced our options to Darwin's laws, or mysterious intelligent intervention by God, Odin, aliens, magic pixies or what-have-you.
But here's the crunch: you could say that about any of the laws of nature. For example, we have the theory of gravity, which accounts, amongst other things for the motions of the planets. Now no-one can deny that in principle, some time before the start of recorded history, some sufficiently powerful being might have made the planets orbit in triangles instead of ellipses for a bit, or indeed played bar billiards with them. But in the absence of any evidence, our default assumption must be that the miracle for which we have no evidence did not take place. When I see a hoofprint, I say "A horse has been here". The mere possibility that it was in fact a unicorn I will acknowledge like a good philosopher --- but I have no reason to believe it, and much reason to believe the "horse" theory.
We should also note that such a supervention of the laws of nature by a miracle would not actually contradict the proposition that they are laws of nature. A miracle means a supervention of the laws of nature --- if they aren't really laws, it isn't a miracle. Hence if anyone discovered that such a thing had happenned, it would mean a big alteration in the story of evolution, but no change to the theory of evolution as it occurs in nature. YECs/IDers have been looking for some example which cannot be explained by natural laws for a hundred and fifty years. The fact that they have now been driven to vague shifty philosophical generalities is in my view a sign that they're beaten and they know it.
In conclusion:
(1) Evolution, in nature, is and must be Darwinian.
(2) Darwin's laws might conceivably have been overridden at some point in the past by a miracle, magic, technology so much in advance of our own that it would seem to be us to be magic --- or by little pixies with fairy dust.
(3) You could say that about any of the laws of nature.
(4) The onus of proof, as with any such claim, is on the person claiming that a law of nature has been violated.
(5) We have no particular reason to suppose that any such thing has taken place.
Biblical literalists, of course, do have a reason --- not a good one, but a reason. The rest of us can look at the fossil record and say "Darwin" with just as much justification as when we see the planets in their courses and say "gravity".
This, indeed, is why the ID/YEC crowd need to attack the whole idea of scientific knowledge and erect another, much stupider concept of knowledge in its place.
One interesting point to note is that this line of reasoning would make the story of evolution absolutely impregnable. The YEC may ask "What use is half a wing?" and the Darwinian is obliged to answer. The proponent of guided evolution can just say: "Goddidit".
This is by the by. Let's look now at the Darwinian point of view, and see if it could have any holes in it.
To summarize, Darwin accounts for the origin of species "from a few forms or one", as he says, by a process of inheritance, random mutation affecting the genotype and natural selection acting on the phenotype. Of course, Darwin did not know the laws of genetics, and we do: instead of "random mutation" he would have just said "variation" without postulating a mechanism.
I hae already reviewed the evidence that Darwin's mechanism is indeed successful in problem solving. But of course we know of two mechanisms for problem solving --- Darwin's or intelligent design. Which should we suppose accounts for the origin of species?
Well, let's review the three planks of the theory. First off, inheritance: I don't think there's any squabble about intelligence.
Second, random mutation. Now, you might wonder whether mutations are random or directed. For example, it would be possible before the invention of modern genetics to suppose that the devlopmental pathway of a creature and its decendants where all programmed out in advance, so that evolution would really be an "unfolding" of the story told in the genes. This would also have been proof of intelligent design.
But we know now that this is not the case. Indeed, not only hasn't this happenned, but it wouldn't work --- there would be no selective pressure on the genes due to be expessed in the future and so nothing to keep them from degrading.
Then again, we might once have dreamed of Lamarckian inheritance, where acquired adaptive traits are inherited. But again, genetics tells us that this cannot be --- information doesn't pass from the phenotype to the geneotype.
Indeed, there be no way in nature for a gene to "better itself". To do that, it would have to "know" whether it would be a good idea to mutate a C to an A, or whether this would be neutral, or disasterous, at that particular location. But there is no way in nature to get from a genotype to a phenotype --- except by expressing the phenotype.
Similarly, we know the external causes of mutation. In order for them to be non-random, a dumb chemical or radioactive particle would have to aim itself at the place where it would do most good to the descendants of the animal it's tagetting.
Finally, observation does in fact tell us that mutations seem to be non-directed and purposeless.
I conclude: mutations are, in nature, random. Now you may well point out that I have not ruled out divine intervention (or, if you will, ETs with technology in advance of our own) and wasn't that what I was trying to do? I'll return to this point. But first, let's look at natural selection.
Can any other natural force act on the phenotype but natural selection? No: by definition. You might as well ask a physicist: "Couldn't there be some other force acting on the body you're talking about besides the net force acting on the body"? No, that would be part of the net force. The pressure of natural selction is the sum of the selective pressures on the phenotype. Anything which isn't natural selection is artificial selection or unnatural selection.
This leaves us, again, either with Darwin to account for evolution, or some mysterious intervention --- God, aliens, what have you. We may note that such intervention, running as it does counter to natural selection, would make the affected animals less fitted to their environment that would be the case if there wasn't any such tampering.
We seem, then, to have reduced our options to Darwin's laws, or mysterious intelligent intervention by God, Odin, aliens, magic pixies or what-have-you.
But here's the crunch: you could say that about any of the laws of nature. For example, we have the theory of gravity, which accounts, amongst other things for the motions of the planets. Now no-one can deny that in principle, some time before the start of recorded history, some sufficiently powerful being might have made the planets orbit in triangles instead of ellipses for a bit, or indeed played bar billiards with them. But in the absence of any evidence, our default assumption must be that the miracle for which we have no evidence did not take place. When I see a hoofprint, I say "A horse has been here". The mere possibility that it was in fact a unicorn I will acknowledge like a good philosopher --- but I have no reason to believe it, and much reason to believe the "horse" theory.
We should also note that such a supervention of the laws of nature by a miracle would not actually contradict the proposition that they are laws of nature. A miracle means a supervention of the laws of nature --- if they aren't really laws, it isn't a miracle. Hence if anyone discovered that such a thing had happenned, it would mean a big alteration in the story of evolution, but no change to the theory of evolution as it occurs in nature. YECs/IDers have been looking for some example which cannot be explained by natural laws for a hundred and fifty years. The fact that they have now been driven to vague shifty philosophical generalities is in my view a sign that they're beaten and they know it.
In conclusion:
(1) Evolution, in nature, is and must be Darwinian.
(2) Darwin's laws might conceivably have been overridden at some point in the past by a miracle, magic, technology so much in advance of our own that it would seem to be us to be magic --- or by little pixies with fairy dust.
(3) You could say that about any of the laws of nature.
(4) The onus of proof, as with any such claim, is on the person claiming that a law of nature has been violated.
(5) We have no particular reason to suppose that any such thing has taken place.
Biblical literalists, of course, do have a reason --- not a good one, but a reason. The rest of us can look at the fossil record and say "Darwin" with just as much justification as when we see the planets in their courses and say "gravity".
This, indeed, is why the ID/YEC crowd need to attack the whole idea of scientific knowledge and erect another, much stupider concept of knowledge in its place.
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