One of the current issues in the Minimalist Programme has been the question of the optimal design of language faculty for meeting the requirements of the external systems. A displacement property may be thought of in this context as one of the imperfections, or conversely, part of the optimal design. The paper, which discusses an instance of movement known as Object Shift (OS), favours the latter position. Object Shift is considered here to be a computational option operative in the formation of a structure legible for an external system. Unlike in Chomsky (1999), I propose that OS is parametrically driven by the presence of EPP in v*, and not by the parametric assignment of the feature [INT] to a shifted object in Spec.of v*P. Some other issues raised in the paper are the question of the autonomy of formal grammar in view of the discussion of legibility conditions,  the interpretation of “external motivation” for narrow syntax, and the status of optional rules.