Thursday, January 10, 2008

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 The scientists who didn’t buy plate tectonics have retired, and many have passed away, and they haven’t been replaced by younger skeptics.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.


CJR said...

There's still a sizeable number of Archean geologists who reckon there was no plate tectonics on the early Earth, I've discovered...

I've always thought that the mantle plumes kafuffle is a good option for an example of a proper and vigorous scientific debate.

Kim said...

Do you have references (or a least a couple authors) so I can track down the articles for the plumes kerfuffle? (I've been a bit out of the loop on things that aren't fought out in GSA Today, due to a number of things - not going to AGU, teaching at a school with a very small journal collection, having a small child.)

I bet there are some Archean guys who are pretty skeptical about paleomag on Archean rocks, too.

andrew said...

The first whiff I ever got of the plumes debate was in GSA Today, 2000, an article offering a no-plume version of Yellowstone. Citation in my old article here.

Chuck said...

Hot spot debate references:
Elements 1-5 for various plume hypotheses, and why hotspots may not be.

Elli said...

The non-plume camp (Don Anderson & former students) has a website entitled: that is a good glimpse into that group. Anderson's definitely got some interesting arguments.

Our grad petrology/tectonic seminar at Iowa got into the plume discussion a number of times. David Peate does hotspot research and we definitely came down more pro-plume in the end.

Spring 2004 we read a number of articles about the plume discussion:
Stein & Stein, 2003, A&G (Feb issue; response to Foulger article in Dec 02 issue)
Anderson, 2001, Science
Dixon et al., 2002, Nature
Fouler & Natland, 2003, Science
Hart, 1992, Science
Montelli et al., 2004, Science
Tarduno et al., 2003, Science

There is also the results from the Penrose Conference -- Plume IV, which may be interesting to the discussion.

Cherish said...

When I took my first geology class (with about 30 people), the prof had us read through some pre-selected papers on the what-killed-the-dinosaurs issue (focusing on deccan flats versus huge asteroid). My impression was that you could do something like this on a limited basis with a lower-level course, and not just those bound for grad school.

I would think something like that would be good for non-scientists to understand a little more about the nature of scientific debate (i.e. that these arguments aren't strictly about poking holes in a thoery but have concrete evidence to back up their assertions).

But it would have to be a smaller class.

It worked on me because I got very interested in geophysics from taking that class.

Chuck said...

Also, radiogenics in the core and upper/lower mantle mixing are interesting 'debate' topics.

MJC Rocks said...

I like your approach. Do you get many students anxious to discuss the "scientific" controversies surrounding Intelligent Design and Creationism? I have had some limited success in getting such students to learn how science actually works, and they begin to see the contrast between religious belief and scientific methodology. Then again, it often makes no difference.

CJR said...

Kim - all of the plume resources given above are a pretty good starting point, although I could dig out some more if you're interested.

And I'm sceptical about Archean palaeomag. There's some rather dodgy studies out there...

Kim said...

Thanks, everyone to links about the plume kerfuffle.

Cherish - one of my colleagues uses the K-T extinction for discussions in Historical Geology. It's the second, not the first, class that students take, so it misses all those students who are just passing through. It would be great, though, to find something that was really accessible to discuss with the intro physical geology/earth systems science students. Even stuff in GSA Today can be hard for the freshmen to wade through, though. And I would rather let the see the debate unfiltered through journalists, so the students can see for themselves how scientists communicate with one another.

MJC - I haven't had many students interested in debating creation "science." That's partly the nature of the things that I teach - I don't do fossils (in part because we've got a good historical geology class that deals with them in detail, and in part because I've got a really weak paleo background.) I did have a couple young-earth creationists in my upper level plate tectonics class once, though. (They were doing student-constructed majors, not the geology major. They avoided Historical and Paleontology, but they wanted to know more about mountains.) I think that they had both come up with complicated reasoning to allow them to handle some science while remaining committed to a literal interpretation of the Bible. So, no, I don't think I made any headway. (I also didn't directly challenge their religious beliefs, though I tried to make the point that the development of plate tectonics use radioactive dating along with lots of other tools, and hoped they would realize that it was a bit odd to say they accepted the movement of plates, but rejected the science used to understand them.)

John Fleck said...

Kim -

This sounds like a fabulous exercise. One of my frustrations as a science communicator is a lack of public understanding of the way disagreement is a genuine part of the scientific process. Out beyond the academy, people tend to hear the latest study about coffee ("But last week I thought they said coffee was *good* for me"!) and think those scientists just don't know what they heck they're talking about.

It creates the fertile ground for the evolution-ID debate, or some of the more egregious climate wars arguments. This may not be exactly what you're trying to accomplish here, but I think it would be useful to have them think about one of the genuine bits of skeptical science on climate - the possibility of a solar influence, say - so they can understand how minority positions relate to majority views on an interesting question. That sounds very much like your original plate tectonics exercise.

To the extent you can school your young charges in the notions that disagreement is a normal part of science, you'd be doing them a great service.