Since formal and substantive equality of opportunity norms are proposed as components of a moral theory of justified social inequality, the full justification of any candidate conception of equality of opportunity must be sought by way of examining the justification of the full theory of justice in which the candidate conception is to play a part. In much the same way, one examines a component of a car, a candidate design for a carburetor for instance, by seeing how the component would function in the car and how well the car with that component in place would perform.