This study endeavours to explicate the relevance of the Marshallian concept of normality in the evolution of supply curves and the price mechanism in time. This concept is based on the contradictory, or at least ambiguous, combination of an ex ante perspective of expectation formation and an ex post inertial dynamics. We first explore the ex ante side of the contradiction by drawing upon the writings of Shackle. Subsequently, we examine Kornai’s conception of the normal state as system-specific. We identify the relationship between normality and the coordination mechanism in Kornai’s ex post approach which may be regarded as an alternative to Shackle’s solution. Finally, the pertinence of the Marshallian concept of normality will be demonstrated, as will its divergent developments by Shackle and Kornai. This leads us to the conclusion that a further development of the concept is required in order to reconcile both ex ante and ex post approaches; this might be based on recent evolutionary analysis.