Brian Marick has written a tantilizing post The Stance of Reaction. In it he says

At this point, Sr. Naveira has at least four reasonable choices. He can step forward, thereby “asking” Srta. Muzzopappa to move backwards. He can step backwards (typically reversing the sweep). He can turn toward her so that they’re facing, causing her to “collect” (bring her feet together). He can take no step at all, but turn his chest to the left, causing her to begin moving counterclockwise around him.

The important thing about Argentine tango (danced recreationally, though perhaps not in a performance like this) is that she does not know which choice he’ll make. She must be balanced in a stance—physical and mental—that allows her to react gracefully to any legitimate move.

I truly hope he’ll expand on this, and how he applies it to the business of software development. I have great admiration for Brian’s intellect and inventiveness. I suspect what he says will help me work on some half-baked ideas I have about effective TDD keeping the code in a state in which it’s prepared to go in any direction, and about Pair Programming being most effective when we work to increase the possibilities open to our partner (a la Improv acting).

So far, Brian seems to be describing the concept of Reaction by saying what it is not–that it is not a reduction to a model. His description of this dichotomy does not match my understanding of how we use models. Online conversation has not clarified my understanding of his description. I suspect that the difficulty stems from us looking at the situation using different models. The appropriate next step seems (to me) to clarify my own model of how models work and are useful to me. Read More