Every instructor for every class decides what material to cover, what to leave out, and how to cover the material they’ve chosen to cover. And every instructor ignores or deviates from the textbook if they don’t like how it covers a particular topic. After all, as an instructor, you have both the freedom and the responsibility to decide the course content. But that freedom and responsibility can be a bit more challenging to exercise when it comes to controversial or contrarian ideas.
So, how do you teach controversial or contrarian scientific ideas? I’m mostly wondering about how you teach them to undergraduates, since in graduate school it’s common for students to take seminars in which they discuss past and current debates in the field. There are various approaches, and I’m curious how folks decide which approach to take.
One approach is to avoid the controversy by avoiding the entire topic. Presumably this is what you do if you don’t think the topic is important or interesting enough to cover. Especially since, if you’re like me, you often find yourself wanting to cover way more material than can possibly be covered. So if you choose not to cover some controversial topic, you’ll have plenty of other topics you can cover instead. Presumably, it’s also what you do if you want to avoid talking about the controversy for whatever reason. Think of high school teachers in many US schools avoiding the whole topic of evolution to avoid getting drawn into a controversy over creationism.
Another approach is to avoid the controversy by just teaching one side, without mentioning other sides. You might do this if you’re confident that one side is right. Either because you know enough to make an informed judgment for yourself, or because you rely on the judgment of some other source (a textbook, the view of an informed colleague, the majority opinion in the field…). Although even if the side you teach is right, your students may be missing out on an opportunity to exercise their critical thinking skills. And if the side you teach turns out to be wrong, you’ve done your students a disservice.
A slight modification of the previous approach is to just teach one side, but briefly acknowledge the existence of other sides. One reason to take this approach is sheer time constraints. I did this once in an introductory biostatistics course entirely focused on frequentist methods. I briefly mentioned the existence of Bayesian methods at one point, just to let the students know that they were out there, and to give them a brief flavor of Bayesian vs. frequentist controversies. But I said (truthfully!) that Bayesian approaches, and Bayesian-frequentist controversies, were simply beyond the scope of the class.
Another approach is to “teach the controversy”. Teach all sides of the debate. Help the students appreciate all the evidence and arguments and come to their own informed views. Indeed, there’s a powerful argument that you should “teach the controversy” even when there isn’t a controversy any longer. Even if a debate has long since been resolved, there can be a lot of pedagogical value in exposing students to that debate, so that they fully appreciate why we now believe what we all believe. And teaching any controversy helps students learn to think for themselves and think critically. On the other hand, this approach only works if there’s some real scientific controversy. Evolution vs. creationism isn’t a real scientific controversy, for instance. As far as scientific matters go, all the evidence and logical arguments are on one side. So “teaching the controversy” wouldn’t be a good way to teach students evolution. (Not that you might not want to discuss to discuss evolution vs. creationism in an evolution class. But you’d do so in order to get students thinking about evolution’s connections to social, political, and religious matters, not to teach the students evolution.) To make this approach work, you do need to get students thinking about which side is right, or how one might figure out which side is right. Just teaching controversies as a he-said, she-said, without digging into who’s right, is the way political reporters cover politics. It’s not the way to teach science.
A final option is to “teach the discussion” (if that term seems unfamiliar, it’s because I just invented it). That is, teach various ideas or points of view, but don’t present them as opposing, merely as different-but-related. For instance, the diversity-stability (or complexity-stability) literature in ecology is a mess, because there are so many distinct notions of “diversity” and “stability” that are related in all sorts of ways. So while there certainly are debates between opposing viewpoints in this literature, they’re embedded in a larger, complex matrix of overlapping ideas and evidence. Focusing in on those debates to the exclusion of all else, or trying to force the entire literature into the framework of a single two-sided debate, arguably gives students a distorted “roadmap” of the diversity-stability literature. Although on the other hand, if the viewpoints you’re teaching really are opposing, it would be a distortion to teach them as different-but-related.
One challenge in deciding between these options is deciding what’s a “real” controversy and what’s not. One way to decide is to look at the number or prominence of people on either side, figuring that that ought to reflect the weight of evidence and argument. But I don’t think that’s a good idea. Historically, controversies in ecology and evolution often don’t arise for scientific reasons like mixed empirical evidence. Rather, they often arise for other reasons independent of the evidence. So the mere fact that people disagree doesn’t necessarily indicate a real, substantive controversy (think of evolution vs. creationism again). Conversely, the fact that most or even all people agree doesn’t necessarily mean there’s no real controversy. Think of zombie ideas (you knew I was going to say that at some point, didn’t you?) 🙂 So personally, I prefer to rely on my own knowledge and judgment in deciding what’s a “real” controversy, rather than relying on the say-so of others.
So, how do you teach controversial or contrarian scientific ideas? And how do you decide how to do it?
Dynamic Ecology 
I bet for a variety of instructors, an initial apt question would be, “Do you teach controversial ideas?” I bet many folks just don’t bring them up, or avoid them because there’s so much else to teach in the textbook. (In my view, though, that goes against the whole point of teaching.)
What I do is give students information about both sides, not of my making, by directing them to evaluate arguments from both sides, by pairing them up in groups of people who disagree and requiring each group to come to consensus. So, I make them argue with one another, requiring specific rational arguments. (I make sure that students are driven mad by not knowing what I think about the matter until we’re done with teaching about it. It was stunning to learn recently that about 80% of my students in a non-majors biology course, most of whom were heading to become classroom teachers, were initially opposed to GMOs on the grounds that they are unhealthful to eat. That makes no real biological sense, but that’s their position from ignorance. I think there’s a solid against GMOs along with all other business practices by multinationals that are socially irresponsible and unethical, but that’s a whole other matter. Anyway, to let the students really understand that a GMO piece of food isn’t medically dangerous, you need to give them the information and reason their own way out of that box of ignorance. Then, you can have a conversation about whether it’s good for the future of agriculture to allow a couple companies manipulate the entire food supply chain.)
One thing to keep in mind is what is considered controversial by students is often not considered as such by experts in the field. I teach the view of the experts as best I can, and only approach controversial topics that I have a broad knowledge base in (because you WILL get tons of questions). I try to pin down what exactly the controversy is. Like you mentioned, with GMOs, the controversy among experts is NOT about whether the technology is safe or not. There is a broad consensus that taking a single gene with a known product and moving it from one organism to another is safe. I focus on a handful of specific applications of GM tech and the controversy that they create (mostly potential environmental problems). Many things that students view as controversial are old news, I find. For example, when I bring up stem cells most students are thinking about embryonic stem cells, and that controversy is, in a way, old news now that the technology for induced stem cells is developing. They often confuse the ozone hole for global warming and the ozone hole is, again, old news.
For a freshmen or non-majors class I’m not a big fan of the “pick a side and debate” method, because it gives people the impression that controversies exist where they don’t and perpetuates these controversies. If a topic is actually controversial, i.e. experts really are divided on a topic, then maybe it’s appropriate.
Very good point.
Likewise, I have very good experience with teaching the discussion (controversy is maybe too strong a word for many topics), e.g. by reading and evaluating opposing opinions from the literature. I had now several independent evaluations in which students explicitly mentioned that this helped them to understand much better how science works, and that they feel now better prepared to evaluate and reflect evidence from the literature.
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