We propose a minimalist approach to parameter theory that gives up the idea that parameters are a predefined list at the initial state of the mind; this leaves one with the hypothesis that parameters are structures progressively added to the mind, under restricted conditions (schemata), to accommodate the Primary Linguistic Data. As a consequence, an inherent asymmetry is predicted between the two values of a parameter: absence vs presence of an added structure. Using a realistic dataset of 94 parameters, we test this prediction: we demonstrate that virtually all parameters display such asymmetry, in two distinct formats. Then, we sketch a preliminary theory of parameter change, and show that the asymmetry between the two values is confirmed by evidence from parameter resetting in diachrony.
