Teaching (some) controversies

My undergrad plate tectonics professor gave us a great exercise, one that really made an impression on me. He had us choose one article or book from a list of articles skeptical about plate tectonics, and write a short paper responding to one of the arguments. I think that was the first assignment I had had in which I evaluated the argument of some other scientist. (I had had plenty of assignments in which I was supposed to figure something out for myself, but I hadn’t really questioned the published literature.)

I stole that exercise the first time I taught tectonics. But it has lost its usefulness with time. The scientists who didn’t buy plate tectonics have retired, and many have passed away, and they haven’t been replaced by younger skeptics. Plate tectonics is old, and settled, and the stuff of Magic Schoolbus books now. Bringing up the old skeptics would be... well, it would be like attacking evolution. Which is another reason why I don’t use the exercise.

But I still want students to encounter disagreements between scientists. For one thing, I figure that if they know how scientists behave when they genuinely disagree, they’ll be able to recognize manufactured controversy. (See: "intelligent design". Or arguments that human production of carbon dioxide does not play a major role in climate.) But that isn't the only reason - genuine scientific arguments are just plain interesting. Science is fun because we don't know everything.

But the assignments can be hard to structure. When the science is at its most interesting, when there’s something unexplained that lots of people are trying to make sense of, the literature... well, it’s chaotic. Every paper has a different explanation, and in many cases, the papers even set up the background in different ways, trying to build the case that their model is best. And it takes a lot of time, and a lot of background, to sort out what data support which model, and to decide which (if any) models are best.

So I tend to choose topics in which groups of scientists have taken sides. Maybe there’s a comment and reply published. Maybe there’s one paper that’s clearly a response to an earlier paper. Maybe there are a number of papers that come down clearly on one side or the other of an issue.

I’ve got a number of different ways to set up discussions. If the papers are fairly short and accessible (like a couple GSA Today articles about whether continental crust behaves more like a jelly sandwich or creme brulee), I have all the students read both papers, and then split the class into two groups to summarize the arguments on either side. If the papers are long, I might spend one day on one paper, and another day on the other. (I did this in Advanced Structure last semester. It worked well in a seminar-style class, but I’m not sure I would do it with anything but a group of very motivated, ready-for-grad-school students.) If there are a lot of papers (such as the papers from the mid-to-late 90’s about the cause of the Laramide Orogeny), I divide the class in half beforehand, and tell each group which side they’re going to be in charge of investigating and presenting.

Sometimes these work really well. The first time I did the Laramide debate with a class, the arguments were pretty new, and I set the class loose in the library, using the Science Citation Index to try to find new articles on one side or the other. I ran into the two teams talking trash to each other in the Science Library – not ideal professional behavior, but enthusiastic, at least.

But sometimes I wonder: am I giving them a misleading impression about the nature of disagreements? When an argument develops two clear sides, it seems like it stagnates. (The Laramide debate has become less interesting, not because the problem is solved, but because it doesn’t seem to be going anywhere new.)

And sometimes the students come away from the discussions with impressions that surprise me. They often believe the most recently published paper – they seem to think that the newest idea must be the most correct one. (But sometimes new ideas get proposed, and published, and talked about... and then rejected. Not big things like gravity or evolution or plate tectonics, but littler things, like the importance of escape tectonics versus orogenic collapse versus lithospheric de-blobbing in the development of a given mountain belt.) Or, worse, the students view the arguments as personal, rather than scientific. Yes, sometimes the arguments do become personal... but that’s not the point. The point should be for the students to evaluate the arguments and figure out which ones are strongest.

Because someday they will be faced with new ideas, and they will need to decide for themselves whether they agree or disagree.