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Separate from the analysis of another's line of reasoning is the formulation of one's own. "If...then" reasoning from data or information must be undertaken without prompting from an external "authority." One must be able to discern possible cause-and-effect relationships in the face of statistical scatter and uncertainty. One must be aware that failure to control a significant variable vitiates the possibility of inferring a cause-and-effect relation. One must be able to discern when two alternative models, explanations, or interpretations are equally valid and cannot be discriminated on logical grounds alone.
As an illustration of the latter situation, I present a case I encounter very frequently in my own teaching. When students in a general education science course begin to respond to assignments leading them to watch events in the sky (diurnal changes in rising, setting, and elevation of the sun, waxing and waning of the moon, behavior of the stars and readily visible planets), they immediately expect these naked eye observations to allow them to "see" the "truth" they have received from authority, namely that the earth and planets revolve around the sun. When they first confront the fact that both the geo- and heliocentric models rationalize the observations equally well and that it is impossible to eliminate one in favor of the other on logical grounds at this level of observation, they are quite incredulous. They are shocked by the realization that either model might be selected provisionally on the basis of convenience, or of aesthetic or religious predilection. In their past experience, there has always been a pat answer. They have never been led to stand back and recognize that one must sometimes defer, either temporarily or permanently, to unresolvable alternatives. They have never had to wait patiently until sufficient information and evidence were accumulated to develop an answer to an important question; the answer has always been asserted (for the sake of "closure") whether the evidence was at hand or not, and the ability to discriminate decidability versus undecidability has never evolved.
An essentially parallel situation arises in the early stages of formation of the concepts of static electricity. Students are very reluctant to accept the fact that, before we know anything about the microscopic constitution of matter and the role of electrical charge at that level, it is impossible to tell from observable (macroscopic) phenomena whether positive charge, negative charge, or both charges are mobile or being displaced. They wish to be told the "right answer" and fail to comprehend that any one of the three models accounts equally well for what we have observed and predicts equally well in new situations. They want to use the term "electron" even though they have no idea what it means or what evidence justifies it, and they apply it incorrectly to irrelevant and inappropriate situations.
If attention is explicitly given, experiences such as the one just outlined can play a powerful role in opening student minds to spontaneous assessment of what they know and what they do not know, of what can be inferred at a given juncture and what cannot.
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