8.7: Inert Knowledge

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We have a great deal of knowledge stored in memory that we can’t access when we really need it. We know it, but we just don’t think about it in cases where it applies. The philosopher Alfred North Whitehead called this inert knowledge.

Most of you remember the Pythagorean theorem. It tells us how to calculate the length of any side of a right triangle if we know the length of the other two sides (if h is the length of the hypotenuse and a and b are the lengths of the other two sides, then h2=a2+b2). On two different occasions, I have seen people engaged in minor construction (building a doghouse and building a bookcase) who went to all sorts of trouble to figure how long various boards should be cut. They could easily have answered their questions by using the Pythagorean theorem, but it just didn’t occur to them to do so. When I mentioned the theorem, they remembered it, but they hadn’t realized that it applied in the case at hand. They didn’t “code” the situation as one where it was relevant, so their knowledge of the formula remained inert, or dormant.

The chief problem with many courses, including critical reasoning courses, is that the knowledge you acquire in them will remain inert. When you take a class, you usually remember things when you need them on a test. But the material is useless unless you can also apply it outside of class. It is surprising, and depressing, how difficult this is. Some of you will become teachers, and this will be a problem you will constantly face. It helps if you think of examples of things, e.g., belief perseveration, from your own life and if you watch out for them outside of class. It also helps if you learn to recognize cues that signal the relevance of something you have learned (like the rules for calculating probabilities, which we learn below) to a given problem.