An organization is typically composed of changing individuals. Now any individual generally has access to many communication channels, of which this … - Kenneth Arrow

According to this point of view, knowledge is, so to speak, a by-product of production or of investment. In research, on the contrary, it can be said that knowledge is the primary product. The distinction between products and by-products is not important for ordinary goods, because in a competitive regime the marginal costs of the two must be equal. But since knowledge does not have the normal properties of an economic good, it is necessary to study each mode of its production.

Strictly speaking, decision theory really is concerned only with the fourth part of the division given above, that is, the determination of the computational methods for optimization. Given the determination of the other three factors―the objective function, the range of policy alternatives, and the model―the ideal picture is that someone, presumable the firm that hires the operations researcher, hands him, on a silver platter, an objective function. By talking to the engineers, or by looking into a few scientific laws, he determines the policy alternatives available and also the model.

Krugman's whole attack is directed at a statement made neither by Arthur nor by Cassidy. Krugman has not read Cassidy's piece with any care nor has he bothered to review what Arthur has in fact said.