05/27/2011 09:26 am ET Updated Jul 27, 2011

Evolution and Christianity: Did We Arrive by Chance?

My last piece was on the Pope and what I believe is his insensitivity to the threat posed to Christian beliefs by modern evolutionary thinking. I don't think I was saying anything very much that I haven't said before, but I was especially struck by his Easter message about the inevitability of human existence, and I suggested that he was not taking seriously the contingency of existence (including human existence) that is apparently entailed by the evolutionary process.

I confess that I was not writing with the New Atheists in mind -- certainly not to curry favor from them -- but, if asked, I suppose I would have said that for once I and they should find ourselves in agreement. And it is indeed true that there has been some favorable response in the New Atheist blogs, although some commentators seem to think that this represents a radical, if unacknowledged, retreat by me from earlier sympathy with Christianity in general and Catholicism in particular. It does not, mainly because there was not much space for retreat. I have long acknowledged my non-belief and I have also long been a critic of many social aspects of Christianity. I believe that science and religion are compatible but that is a different thing from saying that religion is true or good. (Actually, I think that, like most human institutions, there are both good and bad things that can be said about organized religion, but taken as a whole I am not much in favor of anything that is based on what I take to be a falsehood.)

However, I am somewhat surprised to find that I am being strongly criticized for my characterization of evolutionary thinking about the contingency or otherwise of human existence. My point is that I did not think that there was anything in modern evolutionary theory to make us think that humans must have evolved, a claim that I maintain is central to Christians who accept evolution. I mentioned three attempts to show that it is very likely that human-like forms would have evolved, but I argued also that none of these attempts was strong enough to give the guarantee that Christians need.

Specifically, I mentioned the thinking of Richard Dawkins, of paleontologist Simon Conway Morris and of the late Stephen Jay Gould. I should say that (with the possible exception of Conway Morris) I don't think these evolutionists would claim that they are giving absolute guarantees of human emergence, but rather that such emergence is more likely than not. Dawkins thinks that evolution is characterized by "arms races," where adaptations improve through competition between lines and that intelligence might be expected to emerge from such a process. Conway Morris thinks that there are preexisting ecological niches, one such niche is for intelligent beings, and even had humans not occupied it, some species at some time might be expected to find its way there.

There seems to be agreement that I got Dawkins and Conway Morris right. But what about Gould? Famously, he was against evolutionary progress -- a steady, upwards development through time toward humankind -- and in fact I quoted him to this effect.

Since dinosaurs were not moving toward markedly larger brains, and since such a prospect may lie outside the capabilities of reptilian design, we must assume that consciousness would not have evolved on our planet if a cosmic catastrophe had not claimed the dinosaurs as victims. In an entirely literal sense, we owe our existence, as large and reasoning mammals, to our lucky stars.

Yet, and it is here that I got into hot water, I claimed that he too thought that humans might be expected to evolve.

The New Atheists, including Richard Dawkins, are up in arms about this claim. Let me therefore dig a little more deeply into this matter, starting with a full understanding of what I was claiming. When I wrote of Gould thinking that humans would have evolved, I had made it very clear that by "humans" I was not referring to Homo sapiens, but to human-like beings, meaning especially beings with intelligence. I wrote:

As a Christian, humans cannot be just a chance occurrence. Perhaps we could have blue skin and twelve fingers. Possibly we might be hermaphrodites. But we had to exist and we had to have thinking and moral capacities. We had to have brains big enough to do this.

But in light of the passage from "Wonderful Life," quoted just above, could Gould allow even this? I think he could and would and did! In an essay on the search for extraterrestrial life, first published in Natural History and then reprinted in the collection, "The Flamingo's Smile," he wrote: "I can present a good argument from "evolutionary theory" against the repetition of anything like a human body elsewhere; I cannot extend it to the general proposition that intelligence in some form might pervade the universe."

He then went on to quote the leading 20th-century evolutionist Theodosius Dobzhansky, writing in a textbook with other major evolutionists: "Granting that the possibility of obtaining a man-like creature is vanishingly small even given an astronomical number of attempts ... there is still some small possibility that another intelligent species has arisen, one that is capable of achieving a technological civilization."

About this passage, Gould commented: "I am not convinced that the possibility is so small."

He then went on to give an argument that looks remarkably like the argument that is given and endorsed by Simon Conway Morris, namely that evolutionary convergence (where two different lines evolve essentially similar adaptations to survive and reproduce) suggests that even though major intelligence has arisen but once on this earth, it is quite possible that elsewhere in the universe it has arisen quite independently.

Conscious intelligence has evolved only once on earth, and presents no real prospect for reemergence should we choose to use our gift for destruction. But does intelligence lie within the class of phenomena too complex and historically conditioned for repetition? I do not think that its uniqueness on earth specifies such a conclusion. Perhaps, in another form on another world, intelligence would be as easy to evolve as flight on ours.

So I was right after all. But, in concluding, I am less interested in running a victory lap than in bringing the discussion back to where we came in: the relationship between science and religion. There are two main reasons why it is important to get clear the thinking of evolutionists about the emergence of humankind. First, it is important to see if any shade of modern thought about the evolution of humans suggests that our appearance was inevitable. I don't think it does and I don't see the Gouldian position just sketched as altering this negative conclusion. So I think Christians have still got a problem here.

Second, if you are a non-believer, you still want to articulate a world picture that makes sense to you, about humankind and about morality and so forth. I certainly do, and have long been trying to do just this from a Darwinian perspective. Trying to understand whether humans might have been expected to emerge is an important part of this world picture. And obviously, getting right the thinking of one of the most influential evolutionists of the past half century is a key part of this task.