Oh no! The Neo-Ricardians ride again. Look we can go back and fourth on this old saw all day and night. Here is Freeman's response to Gary www.gre.ac.uk/~fa03/iwgvt/ files/01-eea-freeman-gravity.doc
But what both Marxists and Ricardians would agree on is that a) a subjectivist theory of value won't cut it and b) that a abstinence theory of interest and profit is humbug at best, and in Delong's farmer theory of profit pure unadulterated apologia for it neither approximates a real economic system (feudalism or capitalism etc) nor a plausible history of the origins of capitalist development. Not to mention it is a shitty pedagogy. Let the undergrad go wrestle with a 150 year old problem and debate. The worst that can happen is that he or she will figure out that there is more to this earthly economy than can be explained by a well specified set axioms regardless of who is providing them. The best that can happen is that the student will appreciate the complexity of the problem and the political stakes involved in its "resolution."
Travis