In the mid-1980s, as a new faculty member at a non-traditional undergraduate college, I began a course on ecology with a brief review of our place in space. This was prelude to moving down to earth and mapping our geographical positions and origins. One student, however, remained in her own thoughts. Some minutes later "K" raised her hand: "I always knew the sun, not the earth, was the center of the solar system, but do you mean to say... I'd never thought about the sun not being the center of the universe." From her tone, it was clear that K was not simply rehearsing a new piece of knowledge. She was also observing that she had not thought about the issues before but, now that she did, the answer she realized was obvious. What other retrospectively obvious questions had she not been asking? What other re-conceptualizations might follow? These questions pointed her exactly along the path I hoped my students would takeógrappling with issues they had not been aware they faced and generating questions beyond those I presented.

I had known since my childhood about the sun's place in the Milky Way, but some years after the class with K I discovered my own equivalent obvious question after reading Sally Ride's book on the space shuttle to my son. She conveyed the idea that astronauts regained weight as they descended because they got closer to the earth. But weightlessness is not a result of distance from the earth. Where the space shuttle orbitsó300 kilometers upóthe earth's gravity is still 90% of what it is on the surface. I thought about how to explain weightlessness to children correctly. Try thisóthink of swinging an object around on the end of a piece of string. To make it go faster, you have to pull harder; if you do not hold on tight, the object flies off into the neighbor's yard. Astronauts are traveling around the earth fastóat 7.5 kilometers per second. They feel weightless because all of the earth's gravitational attraction on them goes to keep them from flying off into space. The earth's pull on the astronauts is like your pulling on the stringóbut, while you may let go, gravity never stops acting. When the astronauts in the space shuttle slow down, less of gravity's force is "used" keeping them circling the earth and what is "left over" is experienced as weight regained.

After rehearsing this explanation a few times, it occurred to me that the sun's gravitational attraction was keeping me circling around it (at 30 kilometers/second). On the earth I feel "weightless" with respect to the sun's gravity, but that force is acting nevertheless. I had never thought about this; I had considered myself a passenger on the earth, which the sun's gravity was keeping in orbit around it. I then realized that we are also zooming around the Milky Way galaxy, not as passengers on a planet in the solar system, but because the galaxy's gravitational attraction keeps us orbiting around its center (at over 200 kilometers/second, it turns out). It still makes me feel woozy to think of the sun and the rest of the galaxy "paying attention to me" all the time, keeping me moving at enormous speed through space. Is every molecule in the galaxy attracting every molecule of my body every moment, or is there some other way to think about gravity? Perhaps a further radical reconceptualization awaits me, probably involving curved space-time and other Einsteinian concepts.

I have told this two-part story in recent years to start graduate courses and workshops on critical thinking. It points to a profound issue. If students are going to take critical thinking beyond the cases introduced by their teachers, they have to generate questions about issues they were not aware they faced. Lacking any general resolution to this paradox, I usually follow the story with a guided freewriting exercise (see Elbow, P. 1981. Writing with Power. New York: Oxford U. P.), which aims to bring to the surface students' insights. Starting from this lead off: "When I entertain the idea that I haven't been asking some "obvious" questions that might have led to radical re-conceptualizations, the thoughts/ feelings/ experiences that come to mind include...", the students write for ten minutes. They then pair up and describe situations in which they "saw something in a fresh way that made you wonder why you previously accepted what you had." We list on the board short phrases capturing what made the re-seeing possible. The factors are diverseó"relaxed frame of mind," "annoyed with this culture," "forgetting," "using a different vocabulary," and so on. As with many other questions in education, the challenge is to acknowledge and mobilize the diversity inherent in any group.

When I first told the gravity story, some students construed it as a science lesson. I had to clarify my message, which I did when using this course-opening story to practice lesson-plan remodeling. It did not matter whether students understood my weightlessness explanation, provided they puzzled over how questions that retrospectively seem obvious ever occured to them and provided they considered their susceptibility to recurrent reconceptualizations. I ventured that critical thinking was like a personal journey into unfamiliar or unknown areasóinvolving risk, requiring support, creating more experiences than could be integrated at first sight, yielding personal change, and so on. This metaphor differs markedly from the conventional philosophical view of critical thinking as questioning the reasoning, assumptions, and evidence behind claims. Instead of the usual connotations of "critical" with judgement and finding fault according to some standards, journeying draws attention to the inter- and intra-personal dimensions of people developing their thinking. I look forward to hearing from other teachers their stories of learning how to provide the space and support for students to move along their critical thinking journeys.

© Peter Taylor