I am not a critic of Intelligent Design. When it comes right down to it, I generally accept the principles of intelligent design. But intelligent design is NOT science and if one buys intelligent design, one is accepting evolution. I find it odd that people should be such enthusiastic stompers of evolution (a scientific theory) and endorsers of intelligent design (a philosophical construct.)
Scientists who attack intelligent design as "not science" are not being entirely true to themselves. It would be equally valid to attack neo-darwinism. Neo-darwinism is the philosophical construct that grew up around Darwin's original proposal of evolutionary theory. While neodarwinism added some aspects to the theory as a whole (for example allopatric speciation), it also set on top of evolution an interpretive framework. Although the scientists using it would probably think of it as value neutral, it is not. Neo-darwinism assumes as its underpinning the absolute randomness of everything that happens in the natural world and in the mixing of genes. But absolute randomness is, in fact, an axiom, an expectation and it is improvable. Moreover, it is loaded with a philosophical bias that makes the theory including it untestable.
I think it is safe to say that those of us who are not creationists can buy the fact that through the distribution of genetic material animals change slowly over time. We know this is true because selective breeding gives us different kinds of dogs, cats, horses, and even drosophila. Now science can tell us that this gradual change is the result of a shift in the gene pool and science can propose reasons for the shift--allopatric speciation, island biogeography, temperature variation, "survival of the fittest," evolutionary morphospace and baupläne, etc. All of this so far is valid and scientifically testable. You can do experiments for a great many of these things and see if they cause genotype shifts in populations. What is untestable is that the mechanisms behind all of this are random. For example, when we do our experiments, we are using controlled conditions and the happenings are not at all random. The mixture of genes might be to some extent, but we cannot even say that for certain---brownian motion is not a truly random event--it is shown to be weakly deterministic.
Thus the assumption of randomness and unquideness is the philosophical bias that underpins science. Science is the pursuit of explanations of phenomena in the natural world apart from those factors that cannot be observed by science. In other words, science has an underlying "neutral" hypothesis that implicitly assumes atheism. The atheism is not antagonistic (in most cases) it is simply the condition required to try to determine what happens in the natural world. If scientists always had recourse to "the a miracle occurs" their explanations would amount to nothing.
Now, intelligent design comes along with various problems that have been observed before in evolutionary theory. For example, what good is half an eye? Gould proposed an odd little theory called exaption in which he proposed that an organ or body part that had previously served some other function is co-opted to become an eye or ear or something else. Now, as with a number of Gouldian notions, this is not a testable hypothesis it is a speculation. The same is true of his theory of contingency. Contingency is a marxist overlay employing Hegelian dialectical materialism to suggest that if everything did not occur precisely as it occurred in evolutionary history then we must perforce wind up at a different place in the present day. Such a speculation precludes scientific knowledge that the DNA of nearly all species is multiply redundant--that is there are a great many copies of genes that code for certain things that can be turned on and off by regulator genes. Right here we have a mechanism for redundancy. In Wonderful Life Gould speculates that if Pikaia had not assumed its place in the Cambrian Burgess pantheon then vertebrates would not have developed or would have been very, very different creatures. Perhaps. But how do you prove this scientifically? How do you experiment with it? What observational set can you propose that would isolate the appropriate factors and leave us with only the conditions required by Dr. Gould. In fact, there probably aren't any. Contingency is a philosophical speculation supported by a great deal of reasoning but no evidence whatsoever. It is the marxist class struggle imposed on the history of life.
I have demonstrated amply by this point that science has its share of nonscientific thinking. Intelligent Design is part and parcel of this. It is a philosophical lens through which to examine data. It sees what Behe calls "irreducible complexity" and leaps to the causal conclusion, "intelligent design." But it begs the question--we have labeled the thing irreducibly complex, but is it really, and is there some other mechanism to produce this. Obviously Behe does not think so, but Behe is also looking at it through a biased lens. I honestly don't know enough about the biochemical pathways that Behe speaks of to pronounce intelligently on the question of irreducible complexity, but others have suggested that the words themselves entail the bias of the philosophy.
Intelligent design is evolution in theistic garb. That's the first thing everyone should understand. They propose no new mechanisms, they basically accept the Darwinian lines of massive overproduction of offspring, natural struggles, development of species. What intelligent design does is it defies the implicit atheistic assumption of naturalist science and says that all of this is guided by a designer. Now, it may come as a big surprise to you, but this still implies that humans had ape-like ancestors (NOT as is so often stated humans evolved from chimps). The paradigm hasn't shifted. What has shifted is the philosophy through which the paradigm is interpreted. Now we have determinism laid on top of the natural world.
I happen to think that this is the correct explanation of things. God can cause through whatever mechanism He wishes any changes in the natural world. Knowing as He does His own rules and laws, He can easily cause to happen whatever needs to happen to lead to the end. What I reject is that proving this statement falls into the realm of science. It does not. It falls into the realm of religion, belief, and philosophy. God cannot be proven from these mechanisms. Because of its implicit bias, science can only be surprised by God, it cannot find Him in the data. Now, a scientist looking at the data may see God--that is the work of the Holy Spirit communicating through the data--but using that data to "prove" God is simply not viable.
The objection to intelligent design is not that it is bad science (although this is what scientists might tell you) it is that it contravenes a necessary assumption of science and the way science works to make a special exception for a sensitive case. The objection to intelligent design is that it is a philosophical assumption that poses as a theory. It offers nothing that evolution does not offer already. It is simply the theistic side of the coin. Atheists (Dawkins among them) argue that evolution proceeds in a random fashion (a point they cannot prove with any evidence whatsoever) and theists say that it proceeds by design. In either case the mechanism is as Darwin originally suggested--natural occurrences acting upon a population.
So, intelligent design is not a scientific theory, it is a philosophical construct. Evolution IS a scientific theory that must carefully be teased apart from a philosophical assumption of "no intervention." Proper teaching of evolution would require a very careful statement that we can assume nothing about how the mechanism proceeds. What appears random may be random but we cannot prove randomness. What we assume to be guided could be guided, but we can even less assume that.
Intelligent design is a philosophy attempting to disguise itself as a new scientific theory. It offers nothing in the way of evidence or proof of its propositions. It has discovered nothing new and it offers no insight that those of us who were believing Christians didn't have before its formal statement. Through my entire career as paleontologist, I believed and I still believe that everything that happens is guided and determined, watched over and supported by a God who cares and who has an end in mind. But I wouldn't dare propose this as a startlingly new theory of science or faith. Intelligent designers should have the intellectual honesty to examine their underpinnings and admit that what they are teaching is a philosophy--a different slant on the same data. Now, we can debate a different issue which is whether or not public schools should offer this understanding as a philosophical alternative to neo-darwinism; however, that is an entirely different issue and one that requires different "rules of engagement." For the time being I merely wanted to make clear what intelligent design is and what it is not. It is a philosophical construct, it is NOT a scientific theory that can be acted on according to the rules of science. That is why most scientists object to it. How do you disprove "then a miracle occurs?" It is entirely possible that just our use of terms--"irreducible complexity"--presents a barrier to other hypotheses and explanations for those who embrace the terminology.
We need to keep in mind Gödel's theorem, which reduced to a non-mathematical statement boils down to--within any given closed system there are propositions that can be made that cannot be proven using the axioms of the system. Intelligent design is one of these (as is atheistic evolution) neither is provable under the rules of order for scientific investigation.