The p-prim path to enlightenment…?

The Duke of Wellington was once asked how he defeated Napoleon. He replied: “Napoleon’s plans were made of wire. Mine were made of little bits of string.”

In other words, Napoleon crafted his plans so thay they had a steely, sinewy strength that carried them to completion. Wellington conceded that his plans were more ramshackle, hand-to-mouth affairs. The difference was that if one of of Napoleon’s schemes broke or miscarried, it proved impossible to repair. When Wellington’s plans went awry, he would merely knot two loose bits of string together and carry on regardless.

I believe Andrea diSessa (1988) would argue that much of our knowledge, certainly emergent knowledge, is in the form of “little bits of string” rather than being organised efficiently into grand, coherent schemas.

For example, every human being has a set of conceptions about how the material world works that can be called intuitive physics. If a ball is thrown up in the air, most people can make an accurate prediction about what happens next. But what is the best description of the way in which intuitive physics is organised?

diSessa identifies two possibilities:

The first is an example of what I call “theory theories” and holds that it is productive to think of spontaneously acquired knowledge about the physical world as a theory of roughly the same quality, though differing in content from Newtonian or other theories of the mechanical world [ . . .]

My own view is that . . . intuitive physics is a fragmented collection of ideas, loosely connected and reinforcing, having none of the commitment or systematicity that one attributes to theories.


diSessa calls these fragmented ideas phenomenological primitives, or p-prims for short.

David Hammer (1996) expands on diSessa’s ideas by considering how students explain the Earth’s seasons.

Many students wrongly assume that the Earth is closer to the Sun during summer. Hammer argues that they are relying, not on a misconception about how the elliptical nature of the Earth’s orbit affects the seasons, but rather on a p-prim that closer = stronger.

The p-prims perspective does not attribute a knowledge structure concerning closeness of the earth and sun; it attributes a knowledge structure concerning proximity and intensity, Moreover, the p-prim closer means stronger is not incorrect.


diSessa and Hammer both argue that a misconceptions perspective assumes the existence of a stable cognitive structure where, in fact, there is none. Students may not have thought about the issue previously, and are in the process of framing thoughts and concepts in response to a question or problem. In short, p-prims may well be a better description of evanescent, emergent knowledge.

Hammer points out that the difference between the two perspectives has practical relevance to instruction. Closer means stronger is a p-prim that is correct in a wide range of contexts and is not one we should wish to eliminate.

The art of teaching therefore becomes one of refining rather than replacing students’ ideas. We need to work with students’ existing ideas and knowledge — piecemeal, inarticulate and applied-in-the-wrong-context as they may be.

Let’s get busy with those little bits of conceptual string. After all, what else have we got to work with?



diSessa, A. (1988). “Knowledge in Pieces”. In Forman, G. and Pufall, P., eds, Constructivism in the Computer Age, New Jersey: Lawrence Erlbaum Publishers

Hammer, D. (1996). “Misconceptions or p-prims” J. Learn Sci 5 97



Filed under Education, Philosophy, Physics, Science

6 responses to “The p-prim path to enlightenment…?

  1. Wellington won because he had a relation, or two, back home watching his back, in charge of supplies etc I believe a lot of problems in Teaching particularly Maths have been due to novelty introduced by well meaning academics. This has left parents scratching their heads unable to help. I suffered this with simple arithmetic where new procedures confused me and I had to go to the trouble of using Google’s Oppia to find out why.

    Of course well meaning parents are a nuisance too.

  2. But presumably there are some misconceptions which are just flat wrong – active eye, heavy things fall faster..

    Also have you seen Geary’s stuff on “folk physics”?

    • Some very interesting points! At first glance, I’d be tempted to argue that even the “active eye” has some salvageable elements e.g. straight line path between eye and object, albeit going in the wrong direction…

      Again, with your Physics example, by our everyday experience, heavy things DO fall more quickly than light things. I think I read somewhere (Kuhn, maybe?) that the famous dropping things from the Leaning Tower of Pisa experiment carried out by one of Galileo’s students actually convinced most observers that Aristotle was right! It’s only in the absence of air resistance, of course, that they fall at the same rate.

      I only came across the p-prim model very recently and, to me, it seems a better summary of how students think than the “theory theory” misconception model.

      I haven’t come across Geary before but I will definitely read up on it in the near future.

  3. This is a lovely post, and your idea of refining (rather than replacing) matches what I’ve seen from diSessa elsewhere. Have you read his Misconceptions Reconceived? It’s an expansion of this point, and an argument that those researchers who took it as their work to merely catalog student misconceptions were heading towards a dead end.

    Thanks again for the post!

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