For John and other interested parties: I was writing about Clark the scientist. If you buy Georgism, you are easily led to regard Clark as an apologist. On the other hand, if you take the entrepreneur point of view, you presume that all wealth in a pure market economy is the result of either entrepreneur action or luck. In the entrepreneur view, a thing or action is a resource if it is recognized as a means of satisfying wants, such as the things and actions discovered by butchers, bakers, and brewers regarding how they can benefit others and, in the process, earn an income. Otherwise a thing or action is not a good or resource. This is as true of land, space, and other Georgian sources of so-called unearned wealth as it is of the discovery of electrical power, the personal computer, and so on. If you do not accept that, under market economy conditions, a thing or action is a resource only if it is recognized as such by someone acting in the role of the entrepreneur; it is understandable that you would reject the marginal productivity theory and the Austrian theory of value and cost. But, then, you must defend the Georgist view. I see that view as indefensible, although it certain functions as a rallying point for people searching for a way to tax the assumed unearned increment. (If you care to follow up, Davenport among others, carved up the single tax idea; I have a paper on this that I will be happy to share.) The marginal productivity theory, in Clark, is not an effort to describe reality, which contains all sorts of indivisibilities and non-economics factors. It is an effort to formalize the assignment of money values to resources (things and actions). In this sense, it is conceptually like the theory of gravity. A person who attacks gravity theory because it does not explain the rate of descent of a feather simply does not understand the purpose of the theory. (It was not recognized until later, that what the marginal productivity sought to do was to formalize the ENTREPRENEURS' assignment of money values.) Private property rights means that all consumer goods and resources are appropriable and owned by some person. This assumption is made in order to help formalize the tendency described in the marginal productivity theory. Davenport understood this better than anyone when he objected to the use of the theory to justify the personal distribution of wealth in the US.Davenport pointed out that in a real capitalist economy, as opposed to the pure market economy used to represent the tendency, a large part of the wealth was due to expropriation, robbery, theft, and deceit. Burglar tools are capitalized, he pointed out, in the same way that construction tools are. (It is even possible that Davenport was criticizing Clark for making this error and therefore for being an apologist for those who expropriated land from the American Indians, since Davenport spent a significant portion of his life on the frontier in South Dakota. I have not tried to determine who he was referring to.) If you do not see the purpose of the marginal productivity theory, you will not understand why the assumption of private property rights is useful. Indeed, you may not understand the meaning of the assumption. In that case, it will be easy for you to interpret the assumption of private property as part of a program of apologetics, particularly if you believe that Clark is defending people who you think should be taxed. By "the emergence of entrepreneur thinking" I was referring to the thinking of some economists, most significantly Davenport, Knight, and Mises. This thinking began to emerge in the US with the development of the idea of capitalization (Frank Fetter and Irving Fisher, for example) around the turn of the 20th century. "Who, in a pure market economy, is responsible for capitalizing prospective future streams of income and utility?", the leaders in this train of thought had to ask. Who assigns the money values to durable goods and resources, and why? The answer? They are assigned by the entrepreneur role and they are assigned, roughly, according to the principle of marginal revenue productivity. There was a type of entrepreneur thinking in the writings of earlier economists like Cantillon and Say. However, until economists began to conceive of a role that assigns values to capital goods, the earlier economists were not fully taking the entrepreneur view, which is what I mean by entrepreneur thinking (of economists). Pat Gunning