The custom is to think of value added in a corporation (or in the economy as a whole) as just the sum of the return to labor and the return to capital. But that is not quite right. There is a third component which I will call “monopoly rent” or, better still, just “rent.” It is not a return earned by capital or labor, but rather a return to the special position of the firm. . .The division of rent among the stakeholders of a firm is something to be bargained over, formally or informally.
Pointer from Mark Thoma. If this is true, and I believe it is, then the marginal product of a worker cannot be reliably measured, nor can it be proxied by a measure of the wage rate. That makes some of Solow’s early empirical work, and much that followed in its wake, somewhat problematic.
Recall what I wrote.
Separately, each worker’s contribution to the process is not marketable. It is the final product that can be sold. In a sense, there is a “production externality,” in that the finished product is worth something, even though the individual worker’s output is worth nothing by itself. The task of Coasian bargaining among the workers to come up with a way to allocate this externality is onerous, so it is handled by a manager in the context of a firm.
Also, see my post on the Alchian-Demsetz theory of the firm.