Of scientific misconceptions

I was looking today through the National Science Digital Library’s “science literacy maps,” which are a sort of graphic organizer for science concepts, showing what concepts are related to what other concepts. A valuable resource for teachers, certainly. Even more valuable, I thought, at first glance, are the lists of student misconceptions: the things students think they know about science and have trouble unlearning. But then I started wondering about the wisdom of framing that as “misconceptions” and, in fact, about the value of this idea of science “literacy” itself.

Literacy, taken literally (literal literacy?) can mean two things. It can mean, first, an ability to read and write — to decode, interpret, comprehend, and produce text. But can also mean familiarity with or knowledge of specific texts — not the ability to read but what one has read. One is the key to gaining future knowledge; the other is a list of knowledge already gained. Science “literacy” could mean the former — a facility with the tools of scientific inquiry. But too often it devolves into lists of specific things students ought to know or understand. Such a list naturally raises the question of what they don’t know, or of what they think they know instead of what they ought to know — of, in short, their “misconceptions.” Understanding what a student brings to a class is of course tremendously valuable in teaching. Every lesson ought, in theory, to begin with an assessment of where students are in their understanding of the subject. But to frame that prior incomplete or incorrect knowledge as misconceptions undermines, I think, students’ progress towards gaining the first kind of literacy, the ability to think scientifically.

Most “misconceptions” about science aren’t misconceptions at all, but rather perfectly reasonable conceptions based on incomplete evidence. It’s quite obvious, for example, that the earth stands still and the sun goes around it — any fool can see that! For tens of thousands of years, that model of the earth-sun system was the simplest model that fit all the available evidence. To accept it was merely to apply Occam’s Razor. Only when new data complicated the picture did a heliocentric model become simpler, and it took a good deal more data than that — and tremendous work of analysis — to convince Kepler that the earth’s path was actually elliptical and Newton that, in fact, the earth and sun both revolve around their common center of mass.

There’s nothing inherently foolish about believing that the earth is at the center of the universe. I would challenge any lay person to prove to me beyond a reasonable doubt, using the materials at hand and sensory observation, that the earth moves!* That belief becomes foolish — a misconception — only when persisted in despite the availability of contrary evidence. It was clear two thousand years ago from astronomical observations that the sun didn’t make a perfect circle around the earth, and so the Greek astronomer Ptolemy resorted to the idea of “epicycles,” in which the sun makes little ringlets on its path around the earth. Later astronomers, confronted by even more observational evidence, found themselves forced to add more and more complicated epicycles to explain the motions of the planets, until the system became completely unworkable, and only then (and only at the end of his life) did Copernicus publish his far simpler heliocentric model. If it took the collected astronomers of Christendom and Islam fifteen centuries to give up on epicycles, we shouldn’t be too hard on first-graders (or even tenth-graders) who cling to the idea that the sun goes around the earth. That’s especially true given that Newton’s model wasn’t “right,” either; Einstein, faced with new evidence, developed a more complex one — the general theory of relativity, which itself can’t be reconciled with still newer evidence. There is, in fact, no “correct” explanation of the solar system, only intellectual models that permit us to understand it in ever greater depth and to predict its movements with ever greater precision.

This process — in which new observations force the complication of old models until those models become unworkable and must be replaced by new ones — is science itself. If we want to teach science, then, and not merely the collected knowledge of professional scientists, we ought to see these “misconceptions” as logical steps in a student’s understanding of the world, and use them as the basis of instruction rather than something to be fought. If a student’s understanding of the world is an intellectually valid model based on little evidence, the best way to correct — or let’s say rather improve — her understanding is to present her with additional evidence that complicates or contradicts her existing model. The intellectual process by which she develops a more complex understanding and comes to accept a new model (or, ideally, to develop one on her own) is a key part of the scientific method, and it’s far more valuable in the long run than having a “correct” model of the world that in all likelihood will by a superstition by the time her grandchildren are in school. If there is such a thing as “scientific literacy,” it’s not a body of knowledge but that facility with the nature and process of science that permits one to create and acquire new knowledge.

Teaching science that way has its challenges. First, it demands not only continual assessment of a student’s understanding but an ability to challenge that understanding with new problems, activities, demonstrations, or information, rather than merely contradicting it — which in turn requires the teacher to have an understanding of science that is quite deep. Second, it means giving up the comfortable notion of correct answers and clear authority and embracing, instead, the responsibility of convincing students that what you say (or what scientists say) is true. Third, some scientific knowledge is difficult or impossible to demonstrate convincingly in the classroom. Some concepts, like inertia, can be approached but never quite proven. Others, like the complex view of the solar system, may best be approached historically, by exploring why scientists came to reject old models and embrace new ones.

And what about the rest — the current science that laypeople can’t replicate in their basements? Students used to looking at evidence will, I think, be more likely to accept the conclusions and arguments of scientists even when they can’t reproduce them, which may or may not always be a good thing. They will almost certainly be more apt to actively question and investigate those conclusions, which is nearly always a good thing. And they will understand that science is a process, not whatever tentative conclusion happens to have been most recently reported as “fact” in the local newspaper. In any case, I’d rather see schools developing active thinkers and investigators than a crop of kids who can define inertia and parrot the “correct” view of global warming.**

So on further reflection I’d like to drop this idea of scientific misconceptions. I’m perfectly happy to call people out for deliberately ignoring available evidence or for inventing wild, unfounded, untested hyphotheses (and am in fact delighted to have a good laugh at their expense, especially when they’re long and safely dead). But I think we ought to respect children’s — anybody’s — honest and sincere efforts to understand the world around them, and build on those efforts rather than merely contradicting them. Telling them they’re wrong is a good way to get them to shut up, but it’s a fairly lousy way to teach them.

Edit, 11.11.10: I just ran across an article by two physicists, “Common sense concepts about motion,” in which the authors note that “common sense is a codification of experience providing meaning to our natural language…. Indeed, physics and science in general can be regarded as an extension and modification of common sense…. Accordingly, common sense beliefs should be treated with genuine respect by instructors.” Exactly.

*It requires precise trigonometric calculations based on astronomical observations with high-powered telescopes. Good luck.

**Which, for what it’s worth, I don’t dispute, but that isn’t the point.