Monday, April 19, 2010

Why Thought Experiments Work - Non-Verbal Reasoning in Engineers

"Without experiment, I am sure that the effect will happen ... because it must happen that way." -Galileo Galilei

A thought experiment is an experiment in the mind that is usually a test of a theory, principle, or hypothesis. Many breakthroughs in physics and mathematics are due to thought experiments, but thought experiments have also been important in the advancement of mathematics, philosophy, and computer science. The importance of thought experiments seems somewhat counter-intuitive because why should a non-performed experiment be expected to yield new or better information?

John Clement offers an interesting theory why this is so.

"...these simulations can generate new knowledge using several sources, including the 'extended application' of perceptual motor schemas, implicit prior knowledge, and spatial reasoning operations, in contrast to formal arguments."

Clement goes on to speculate that thought experiments tap into implicit (not expressed) 3D spatial knowledge using analogous mental models. Important thought experiments in science were not flights of fantasy, but rather "distillations of practice, based on real-world experience."

Other interesting features of successful thought experiments were that they could used to expose conflicts in an existing theory - and so play destructive as well as constructive roles in the modification process.

In studies of engineers doing thought experiments such as the one at right (will a wire with coils twice as wide stretch more or less with the same weight?) , kinesthetic and visual imagery were used to solve the problems, and as the engineers used twisting motions of their hands, the actions seemed to tap into implicit knowledge about how the springs would behave.

It's interesting in his video recordings of the engineers that most also seemed to manipulate the springs beyond the condition in the problem for instance: Now I'm confirming (moves clenched right hand toward clenched left hand) that, by using this method of limits. As (moves right hand to left hand until they almost touch at the first word "closer") I bring my hand up closer and closer (keeps holding clenched right hand next to left hand, making slight vertical punctuating motions at the words "hold," "clearly," "harder," and "harder") to the original place where I hold it, I realize very clearly that it will get harder and harder to twist. So that confirms my intuition so I'm quite confident of that." 

Adding extreme cases to thought experiments allowed the engineers to test out their predictions and change their theories appropriately depending on the results.

What are the take-home points for education?

1. Thought experiments can be valuable both as a source of new ideas and in critical analysis of existing theories.
2. Because success at thought experiments often employ perceptual-motor knowledge that can only be gained through direct hands-on experiences, we should not consider a complete education 'hands-off' education.
3. Imagery is essential to many types of generative thinking; practice in imagistic reasoning might be a valuable addition to the educational arsenal.

Thought Experiments in Science and Science Learning pdf
Thought Experiments - Wikipedia

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