While I’m not as bothered by the Pope’s statement about evolution as PZ is, what’s troubling is the scientific misunderstanding shown by his statements.
I agree with one sentiment, which is that biology doesn’t tell us much about meaning, since I think meaning is something we ascribe to physical reality (and events). Many biologists have made much philosophical and ethical hay of the common ancestry of humankind, so it’s certainly reasonable for the Pope (or anyone else) to do so. What is really disturbing is how ignorant he is of modern biology and science. According to the Pope:
“The pope (John Paul) had his reasons for saying this,” Benedict said. “But it is also true that the theory of evolution is not a complete, scientifically proven theory.”
Benedict added that the immense time span that evolution covers made it impossible to conduct experiments in a controlled environment to finally verify or disprove the theory.
“We cannot haul 10,000 generations into the laboratory,” he said.
Let’s take the last part first. Richard Lenski, at Michigan State, has evolved organisms (in this case, E. coli) for 30,000 generations. This is a controlled defined experiment, and because bacteria can be cryogenically stored and then ‘thawed out’, there is actually a living fossil record of evolution. For more information, check out the E. coli Long-term Experimental Evolution Project site. Granted, it’s impossible to conduct a similar experiment on elephants, but the Pope is wrong on the facts.
But the statement reveals a much more fundamental problem, which is a basic misunderstanding of the role of experimentation in science. More precisely, he does not understand the basic limitations of experimentation. Experiments, just like mathematical models, can elucidate mechanism in and only in the context of the experiment. In other words, an experiment designed to examine the role of an enzyme in a biochemical pathway in a laboratory setting really only tells us what is happening to that cell under laboratory–and usually, artificial–conditions. The unstated assumption is that ‘cells are cells': the mechanisms won’t be too different inside the lab versus outside the lab.
Ultimately, to “finally verify or disprove” any experimental phenomenon, one needs two things:
1) Observations that verify that the experiments bear significant semblance to ‘things out there.’
2) Experiments in different conditions that approximate the range of natural settings. There’s not much point in assessing the growth of cacti in conditions mimicking tropical rainforests (unless you want a bunch of really big cacti).
Even here, there is no ‘final proof’, only a rigorous, good faith effort to falsify your hypothesis (if you’re a Popperian), or an exhaustive effort to find the most likely hypothesis (if you’re a likelihood proponent).
There’s one other odd thing: the Vatican has an astronomer. How does one do manipulative experiments in astronomy? Maybe he should have talked to his own scientists first…