“The surplus becomes the firm’s profit.”

 “The surplus becomes the firm’s profit.” — That’s the starting point. In modern terms, the Fundamental Marxian Theorem (FMT) says that, within a linear-production framework, if the value added created by labor exceeds the wage bill—i.e., there is a surplus—then a positive uniform profit rate exists in the price system; conversely, if a positive uniform profit rate exists economy-wide, there must be a surplus of value over wages. These two claims are logically equivalent. Morishima first gave a precise formulation; Roemer and others later generalized it. In parallel, Okishio’s theorem makes a different point: if the real wage is held constant and firms adopt cost-reducing techniques, then the new competitive equilibrium features a higher general rate of profit. Okishio is thus about comparative statics of technical change and the profit rate, not about the surplus-profit equivalence itself. Both strands sit on the Sraffian long-period price theory, where a uniform profit rate emerges as the distributional parameter trading off with the real wage—intuitively, the system’s average return on capital (akin to an interest rate). Recent literature relaxes some assumptions (on wages, equilibrium concepts, or evaluation methods), showing how conclusions can shift with conditions, but the core distinctions above remain standard