As a devout evolutionist and Darwinian, I have often struggled with friends who are enthusiasts about so called Intelligent Design Theory. Often I remind them that the theory is not science because it does not follow the scientific method and is more of a philosophical than a scientific argument. Second, it is abundantly evident that the so-called Intelligent Designers are basically just a bunch of Christians who want to get a form of creationism into the scientific curriculum. I have had the discussion enough that I thought I would eventually write a book about it. Luckily, I do not have too.
Historian of Science Michael Shermer in his book Why Darwin Matters: The Case Against Intelligent Design masterfully and amusingly takes the Intelligent Design theorists to task and shows how, in large measure, the Intelligent Designers do not have a case and how religious people can both believe in God and also accept scientific evidence.
The book begins with Shermer and a colleague exploring the Galapagos Isles; the same Isle's that Charles Darwin explored before authoring On the Origin of Species. He notes that the Isle's are difficult to get around, and are very threatening to certain kinds of life, and that over time he saw how animals that were on the Isle's during Darwin's journey there had changed and adapted to be better suited to survive. As he puts it "There can be no doubt: evolution happened."
Shermer then goes on the defensive, showing that evolution is a historical science; you don't see it while it is occurring as much as you do after it has occurred. He also points out that not only biology gives us evidence of evolution, but paleontology, geology, anthropology, and so forth. So, we can have a strong conviction of evolution and it is because various sciences and studies converge to the exact same conclusion. If evolution did not happen, it would be very odd for people of many disciplines to all converge to the same general framework.
Next, Shermer gives the various reasons people don't believe in the theory, and shows they are ill founded or have been countered. In large measure, part of the problem is about words, which as an analytic philosopher I would say most problems come from. When people hear the word theory, generally they take that to mean that this is someones idea that their acceptance or non-acceptance of will be of little difference. In science, a theory is based on empirical evidence, and is used to interpret the evidence. So, evolution is a theory based on evidence, and is able to explain life and complexity more than satisfactorily. For this reason, it is universally accepted in the scientific community, but people outside of it do not understand the meaning of the term, so they feel that Darwin's theories are of no more importance than those of Mary Baker Eddy. Newsflash: Darwin was right and Eddy was... well I don't want to go there but you get my point.
After explaining Darwin's theory, Shermer gives the arguments from the Intelligent Design side. He points out that most of them are just asking a question rather than making an argument. For instance, Intelligent Design theorist Stephen C. Meyer points out that the Cambrian Explosion is incompatible with Darwinism because these animals just appeared rather than descending from prior known forms of life, and states that even Darwin himself was perplexed by this. Shermer then points out that the current fossil record shows that the Cambrian Explosion was not really an explosion and that it is explainable by natural selection and random mutation. I must say, for a Cambridge philosophy graduate, Meyer makes me ashamed to be a philosopher. Yikes!
Shermer concludes by talking about the conflict between science and religion (which is not a conflict at all as far as I am concerned), and invokes the late paleontologist Stephen Jay Gould's idea of non-overlapping magisteria; which is that science and religion are about two different things, the former is about the empirical world, and the other is about morals, values, and so on.
Here I must disagree with Shermer and Gould. First, there is an overlap in some religions with science because some religions believe in miracles which are by definition "A violation of the laws of nature" as Scottish philosopher David Hume stated. Also, I am not sure that religion has its own magisteria to claim if it is solely about ethics; there are many moral philosophers, psychologists, and theorists who engage in these questions everyday, and some do it better than those who are religious. It would be better to say that religion is not interested in the same questions as science, and that there really is no conflict unless we make it into one.
I will close with this quote from Shermer's book, which sums up the whole debate and problem very beautifully:
"Darwin matters because evolution matters. Evolution matters because science matters. Science matters because it is the preeminent story of our age, an epic saga about who we are, where we came from, and where we are going."
Because science matters and because many in America are uniformed about these matters, I strongly recommend that you pick up Shermer's book and educate yourself. If we are going to have a conversation that is constructive, we must be informed.