Gary Mongiovi writes: "Ricardo states quite clearly, in CH. XXX of the Principles, that deviations between S&D explain deviations between market price and long-period normal price, and that the latter is not determined by the forces of S&D but by cost of production: he is here explicitly rejecting Malthus's theory, so James errs, I believe, in placing them together on this issue. If we take Ricardo at his word, as we should, he had a very different theory in mind from modern textbook S&D theory." Ricardo does state the S&D theory of price in chapter 4 of the _Principles_, following Smith, thus: "Suppose now that a change of fashion should increase the demand for silks, and lesson that for woollens; their natural price, the quantity of labour necessary to their production, would continue unaltered, but the market price of silks would rise, and that of woollens would fall ..." (pp. 90-91). In chapter 30, Ricardo quotes extensively the Earl of Lauderdale's explanation of the price of commodities by supply and demand, including (1) "an increase ... from a diminution of ... quantity," (2) "a diminution of ... value from an augmentation of ... quantity," (3) "an augmentation of ... value from the circumstance of an increased demand," and (4) "value might be diminished by a failure of demand" (p. 384). Ricardo agrees with the above and more, but disputes the completeness of the explanation for the long run: "This is true of monopolized commodities, and indeed of the market price of all other commodities for a limited period. If the demand for hats should be doubled, the price would immediately rise, but that rise would be only temporary, unless the cost of production of hats, or their natural price, were raised" (pp. 384-85). The argument very much reads like Alfred Marshall's tracing of an industry's long-run supply curve as taught in modern microeconomics -- an increase in demand leads to a rise in market price along a rising short-run supply curve, followed by a shift of the supply curve, which then changes the long-run price. Ricardo does close chapter 30 with an argument that would appear to some readers as his negation of the S&D theory of market prices: "but the prices of commodities, which are subject to competition, and whose quantity may be increased in any moderate degree, will _ultimately_ depend, not on the state of demand and supply, but on the increased or diminished cost of their production" (p. 385; my emphasis). Now understand supply as being determined by the cost of production, and then you find that Ricardo's objection to the S&D theory in the long run, as argued by the Earl of Lauderdale and Malthus, is more of semantics than substance. None of those with whom Ricardo disputes would disagree that a permanent reduction in the cost of production would lower price in the long run. Indeed, Ricardo (p. 383) quotes J.-B. Say as having made the same point: "the cost of production determines the lowest price to which things can fall: the price below which they cannot remain for any length of time, because production would then be either entirely stopped or diminished." One of J.S. Mill's (3: 467-68) principal clarifications of the S&D theory of price was to distinguish supply form quantity supplied and demand from quantity demanded, just as modern microeconomics teaches. That distinction was not clearly made in some of the earlier statements of the theory of value (or price), including that of Ricardo. For example, Ricardo claims that "The demand for a commodity cannot be said to increase, if no additional quantity of it be purchased or consumed; and yet, under such circumstances, its money value may rise" (p. 382). But an increase in demand (shift of the curve to the right) along with a significant decrease in supply (leftward shift) would describe the circumstance Ricardo is disputing. Thus, to insist, as Gary does, that S&D theory of market prices is a post-1850 development is to misrepresent the classical literature, just as some other contributors have noted. So is the insistence that Ricardo does not belong in the same (classical) tradition as Malthus, their semantic disputes notwithstanding. James Ahiakpor