J.B. Clark was an American bourgeois Economist and apologist of capitalism. He was the first economic theorist of the United States who achieved an international reputation. He was born and raised in Providence in 1847.

Among his major works, ‘The Distribution of Wealth’ (1899) and ‘Essential features of economic theory’ stated that, in a bourgeois society the state protects the rights of citizens to obtain the equivalent of the product they created and therefore there is no exploitation. Divide the economic theory into two parts: static and dynamic. Emphasis needs to be expressed that with the political economy should begin the study of economic phenomena by static, that is, taking as a constant numerical population, the magnitude of the capital, technical level, the organization social production and the needs of men. If you change just one of these conditions that characterize static, it is passed to the dynamic state.

The division of economic theory in static and dynamic reflects the tendency of approximating the Political Economy and the mechanics of this sort, aside from the investigation the most acute social conditions rending capitalist society.

One of the most important "laws" Clark devised for static state of society is the "law of diminishing productivity of labor and capital." Such "law" is on the basis of the "theory of marginal productivity", according to which each new increment of labor, given the same amount of capital, gives a lower productivity than the preceding increase. Comparatively, each new capital increase, keeping unchanged the number of workers, production yields less than the previous. The law follows that:

-	Each additional worker has lower productivity than the previous, and

-	Product value creates not only the worker, but also, capital, and therefore the claim of the capitalist to receive profit is based.