The IDists are spreading a fallacy. Scientists do look critically at evolutionary theory. IDists seem to think that they’re all indoctrinated in grad school and never actually think. The truth is, the evidence supporting it is so overwhelming that it doesn’t admit any alternative hypotheses worth thinking about, and any biologist that does any critical thinking will come to the same conclusion.
There’s a pseudoscientific theory that evolution occurs by “morphogenetic fields”; sort of a weird variation of Larmarkism IIRC.
I think Hoyle’s support of the steady state theory long after the preponderance of evidence supported the Big Bang theory had more to do with that.
Darwin of course did not know how traits propagated, so in the Origin he proposed a Lamarckian type of mechanism. As mentioned above, the strength of his theory is demonstrated by the fact that the discovery of the real mechanism supported it even better than the mechanism he proposed.
I thought someone should probably mention that despite the numerous revisions and changes over the last 150 years, the Theory of Evolution is still essentially Darwinian in character (hence the name Neo-Darwinian), and even Punctuated Equilibrium, Kin Selection, and other modifications are just that: modifications rather than refutations of Darwin’s thinking. Often Creationists mischaracterize modification and changes to the theory as a rejection of Darwin by mainstream science.
Perhaps the biggest scientific challenge to Darwin’s thinking is lateral transfer of genes between lineages, but to this day no-one really knows how important that is.
And yet, without evolution, no disease resistant organisms could ever happen.
From Discworld we have the force of Narrative, carried by a material called Narrativium. Narativium constrains life to form itself to fit really good stories.
In the discussion of evolutionary theory, we must always remember just what question Darwin was answering:
How did the world come to sport such a wide diversity of life forms, given that some are widely different in form, and some are nearly identical but can not mate?
Darwin, taking into account the established fact that species are malleable, and after performing careful breeding experiments where, for example, he took one existing variety of pigeon and, through several generations of careful selective breeding, generated another established variety of pigeon, came to the conclusion that changing physical environments unconsciously create conditions where some members of a species are favored over another prior to breeding, the same way a breeder might consciously select or reject potential mating partners. Not really all that controversial sounding, when you come to think of it.
Darwin’s Theory has much evidence to back it up, such as the case of the pepper moth in great Britain. Genetics was later revealed to be a mechanism by which traits were passed on to subsequent generations so that evolution could happen.
So an alternative theory would have to explain the pepper moth and many other cases without the feature of natural selection. Can’t think of any, myself.
Now the “irreducible complexity” argument is somewhat interesting, in that there are structures, such as the eye in higher animals, and bat wings, where we can not see how rudimentary forms of these had a reason to evolve in the first place, much less provide an advantage that allowed them to take on their currrent forms. However, rudimentary eyes, for example, only present a problem if they spell out such a survival disadvantage that the continued existence of the creature can not be explained. Which is why IDer’s, and not scientists, are obsessing about it.
There are a number of philosophical/religious alternatives, for example, that the physical universe is an illusion (and so requires no explanation of how it works).
Or that it came into existence last Thursday, complete with fake provenance (and so examining it cannot reveal the truth of it’s last-Thursday origin).
This is news to me! Have you any cites?
There is some evidence as one of the posters above mentioned that organisms can modify their DNA in response to external events and pass that on to their offspring. This involves switching off (or possibly on) certain genes in response to famine or such like. These genes remain switched off in the next generation. This is part of a new field called epigenetics
It’s worth critical examination in the same respect that it’s worth being open to the idea that the earth doesn’t revolve around the sun. Evolution is as about as well-proven as that; it’s certainly not valid to teach other alternatives as significant possibilities without pointing out that there are no scientific alternatives and that the evidence firmly demonstrates the validity of evolution.
You imply that Creationism and Intelligent Design are “scientific theories”, which is incorrect, as they don’t produce testable hypotheses. There’s no way to prove an Intelligent Designer, as the “irreducible complexity” posited by IDers simply means that we haven’t found an exact evolutionary mechanism to explain some feature. In most of the examples IDers cite, there are of course possible mechanisms that have been suggested; logically, it’s nonsensical to claim just because we don’t know exactly the process that led to some anatomical structure that we therefore have to resort to supernatural explanations. Intelligent Design doesn’t produce any testable claims - there is no way to find positive evidence that demonstrates the involvement of a “Designer”; the gaps in lineage (the instances of “irreducible complexity”) are simply spots where we haven’t figured out the exact sequence of events that occurred, and these are getting smaller all the time.
I figured that someone would bring that up. I am in the middle of reading Brian Greene’s latest book (whose name I have forgotten, but it is a survey of modern physics). In his discussion of time, he makes the point that not only is it possible that the universe was created last Thursday, it is overwhelmingly more likely than an earlier date (and less likely than a later one). The reason is entropy. Entropy is always increasing and a state of lower entropy is always less likely than one of higher entropy. And the big bang, if any, was the state of least entropy and therefore the least likely. Since I don’t believe any of this (and neither, I assume, does Greene), this leaves our belief in the usual cosmological stories something like a religious belief!
As for ID, the main difficulty in putting in a science course is that there is no scientific theory there. It has no testable consequence and suggests no research program.
The eye is actually very easy to explain by evolutionary theory. Much harder are the criticisms the ID people make of blood clotting. As it stands it is hard to come up with an evolutionary story, since it involves something like 19 (IIRC) enzymes without which there is no clotting at all. Assuming the facts are correct, that requires an explanation. Such an explanation will likely take the form of showing all these enzymes had other uses and then were adapted to clotting. But I would like to see what an evolutionary biologist would say.
I find it interesting that not a single doper has defended ID.
The horrifying thing is that the Kansas Board of education has redefined “science” to include supernatural explanation. Reminds me of Lincoln’s dog story. (Lincoln was asked that if you call a dog’s tail a leg, how many legs does a dog have? “Four” was his answer. Let us redefine “Kansas” as a state of ignorance.
Why? What problem do you see with evolutionary theory that needs an alternative hypothesis to resolve?
What’s the formal name for the “you’re really a brain in a vat” theory of existance?
I don’t know that I am personally convinced that evolution is solely a matter of random mutations + survival of the fittest, rinse and repeat. My subconcious is able to control my breathing, blood pumping, T-cell routing, etc., etc. without my ever realising it is doing it. If when my body starts creating happy spermlings it does some subconscious figuring and chooses particular mutations to add and test, I see no reason to be surprised. Whether such a thing is actually occuring, I have no idea of course. But you could test it simply by subjecting a few (particularly higher-intelligence) species to adverse conditions and seeing if the amount of variation in the offspring is greater than in a control group, and then whether there is a pattern to it (e.g. more hostile predators = wider variety of coloration, hotter temperature = less fur, etc.)
I don’t think such a theory would be in conflict with Darwinism, as originally 100% Darwinist evolution would have been necessary. But once the organisms passed the stage from a random self-replicating chemical reaction into an autonomous being, I see no reason to believe that some amount of rational (if limitted) logic isn’t being included in the process of breeding beyond “hey he’s hot,” and rather down the level of trying to improve the inner workings of particular organs and internal chemical reactions.
The very essence of good science is to always be questioning and always examining alternatives.
If you have Theory A which adequately explains the data (ie is not in need of an alternative) that is no reason of itself to stop looking at Theory A critically, and stop thinking about whether Theory B might not be a good theory too.
That is not a contradiction: there could quite easily be two theories about a given phenomenon, either of which fit the data.
Evolution is a fabulous Theory A. There is no good Theory B. But as a matter of principle, that does not mean we should not continue to look critically at Theory A, and stop considering Theory B’s.
Furthermore, as a matter of politics, your comment has a whiff of dogma about it and there is nothing ID’ers like better than to accuse evolution as being that.
Split infinitives be damned.