"Professor Theophilus! Mind if I share your table?"

I looked up at Ling in surprise. "Pull up a chair. I haven't seen you for what — two, three semesters?"

"My lab courses are keeping me pretty busy. Actually, I tracked you down." He grinned. "The receptionist said 'He's grading essays. Try the Union.' Doesn't the noise here bother you?"

"Keeps me awake. What's on your mind?"

"Well, I'm getting pulled in opposite directions, and I hoped maybe you'd have some thoughts."

"How so?"

"It's this whole science-religion thing. There's Genesis. God created everything. Okay? But then there's my genetics prof. He says 'Get this through your head. Evolution is a fact. A proven fact. Religion has nothing to do with it.' Well, I want to be a good scientist. But I want to be a good Christian too, and I can't quite buy this 'nothing to do with it' line."

"Ling," I said, "I don't even own a lab coat."

"You're covered with chalk dust most of the time, and it looks a lot like a lab coat."

I smiled wryly. "Busted."

"Besides, you teach about philosophy of science."

"Sometimes."

"So here's the deal. What I'd like to believe is that God created everything, but evolution was his method for doing so. But is that logically possible?"

"I can't answer that because it's not a well-formulated question."

"Why isn't it?"

"Because 'evolution' means too many things."

"The other day my genetics professor said 'The best one-word definition is simply "change."' What's so funny?"

"Sorry. That, Ling, is what's called a tendentious definition."

"I don't get it."

"Nobody denies that things change. If I loosen my tie, the tie is changed. If I sip my coffee, the coffee is changed. But when people argue about evolution, that's not what they're arguing about."

"Okay, but he wasn't talking about all kinds of change. He said later that he meant change in the characteristics of a population of organisms."

"Still too broad. By that definition, evolution happens whenever your genetics class learns something."

"I think he meant change in a population's genetic characteristics. Anyway, that's what the textbook says. It defines evolution as change in the relative frequencies of alleles. Oh, sorry. Alleles are —"

"I know. Variant forms of genes, like genes for thin or stubby fingers."

"Right."

"But Ling, nobody denies that gene frequencies change, either."

"No?"

"No. Take Darwin's famous finches. Over many generations, genes for long beaks may become either more or less common relative to genes for short ones — so the average finch beak may become either longer or shorter. This isn't controversial even in religious circles."

"Then what are people arguing about when they argue about whether evolution is a fact?"

"To answer that question, I have to ask you another. Suppose you suggested to your professor that sometimes fairies intervene to change gene frequencies. That fits his definition — change in gene frequencies — but would he really call it evolution?"

Ling hesitated. "No, I don't think so. His favorite expression for ideas he considers unscientific is 'fairy tales.'"

"Then what he really means by evolution isn't just changes in gene frequencies."

"I guess not. What he really means is what causes gene frequencies to change."

"Now I can answer your question. That's what people are arguing about when they argue about whether evolution is a fact."

"They're arguing about the causes?"

"Right."

"My professor says gene frequencies change because of natural selection and inheritable variation."

"Do you understand those terms?"

"I think so. Say a chance copying error takes place, and gene X mutates into a new variation, gene Y. That's an inheritable variation."

"And natural selection?"

"Let's say this new gene, Y, promotes reproductive success. Then organisms carrying gene Y have more offspring than organisms without it, and over many generations gene Y becomes more common in the population. If gene Y turns out to be harmful instead — which it almost always is — then the opposite happens. Of course this isn't a sure thing. We're talking probabilities."

"So both natural selection and inheritable variation involve chance."

"Right."

"Okay, let's go back to something you said earlier."

"What?"

"You'd like to believe that God created everything, and evolution was his method for doing so."

"Right. Evolution happens, but He guides it."

"Evolution being a combination of two chancy processes."

"Right."

"Don't you see the problem?

"No."

"Think about it."

"Oh, wait — I get it — if the two processes really depend on chance —"

"Keep going," I said.

"— then they can't be guided."

"Right. What do you think?"

"Um — maybe God arranged the process so it looks like chance, but it really isn't? Like loading the dice?"

I took a sip of coffee. "Ling, I don't deny that an all-powerful God could have done something like that. He might have created everything — then covered His tracks, wiped off his fingerprints. That's one way to reconcile neo-Darwinism with belief in the Creator, and some people find it attractive. But there are two big problems with it, one religious, the other scientific."

He scrunched his eyebrows. "What are they?"

"The religious problem is that according to revelation, things don't look like they've arisen by chance. They look designed. Paul says in Romans 1 that ever since creation, the reality of the Creator has been plainly understood 'from what has been made.'"

"Well, sure. But that's only how things look through the eyes of faith."

"I'd say they look that way to everyone."

"Isn't 'everyone' a little strong?"

"I don't think so. Even the arch-Darwinist Richard Dawkins says 'Biology is the study of complicated things that give the appearance of having been designed for a purpose.' And that presents not a religious problem but a scientific one."

"My professor would probably say that things only look designed if you haven't learned biology. Once you know about natural selection and inheritable variation, then the process looks like chance."

"You said you wanted to be a good scientist. How does a good scientist settle a question?"

"By evidence."

"Then let's talk evidence. On a small scale, we do have evidence of both inheritable variation and natural selection. That's not in dispute."

"Then isn't the questions settled?"

"I said 'on a small scale.'" It's one thing to say that those two processes turn short finch beaks into long ones. It's quite another to say that they turn fish into frogs."

"Isn't that just extrapolation? Over long enough periods of time, wouldn't little changes add up to big ones?"

"You'd think so, but that's not what seems to happen. The fossil record doesn't show a continuous, gradual accumulation of small changes; what it shows is long periods when hardly any change takes place at all, interrupted here and there by short periods of large, abrupt change."

"Is that your own observation?"

"Don't take it from me. I'm no paleontologist. Stephen J. Gould, who is one, calls it 'the trade secret of paleontology.' That's not the biggest problem, either."

"What is?"

"Many of the systems that operate inside living things have a property called 'irreducible complexity.' Irreducibly complex systems are highly unlikely to evolve through successions of small changes. An example given by biochemist Michael Behe is the chemical system that retinal cells use to detect light. All of its parts have to work together. It's not as though if you had one part then a little light would be detected, and if you added another part then a little more would be detected. Unless all the parts are there at once, no light is detected at all."

"Couldn't all of the parts have arisen at the same time?"

"That would be a mighty big coincidence — and you'd need lots of mighty big coincidences, because there are lots of irreducibly complex systems. At some point, the concatenation of all these coincidences becomes so fantastically unlikely that you have to say 'Okay, things still look designed.'"

He chewed on that for a bit.

"Professor Theophilus."

"Still here."

"Are you saying that a Christian scientist can't believe in evolution?"

"No, I'm not. For example, you might argue that although the biblical writers say that the designedness of things is plain, it doesn't follow that there will ever be scientific evidence for design. That's true — it doesn't follow — although I think you should at least be open to the possibility."

"How would you advise me, then?"

"There's an extensive literature on what would count as scientific evidence for design. So learn about the controversy — both sides. You might in the end decide that my own view is wrong."

He got up to leave. "Thanks! Any last words?"

"Just one. Watch out for the idea 'If it points to God, it can't count as evidence.' That's not science."

"What is it, then?"

I raised an eyebrow. "Religion."