CHAPTER XXVIII.
ON THE INFLUENCE OF DEMAND AND SUPPLY ON PRICES.
It is the cost of production which must ultimately regulate the price of commodities, and not, as has been often said, the proportion between the supply and demand: the proportion between supply and demand may, indeed, for a time affect the market value of a commodity, until it is supplied in greater or less abundance, according as the demand may have increased or diminished; but this effect will be only of temporary duration.
Diminish the cost of production of hats, and their price will ultimately fall to their new natural price, although the demand should be doubled, trebled, or quadrupled. Diminish the cost of subsistence of men, by diminishing the natural price of the food and clothing, by which life is sustained, and wages will ultimately fall, notwithstanding that the demand for labourers may very greatly increase.
The opinion that the price of commodities depends solely on the proportion of supply to demand, or demand to supply, has become almost an axiom in political economy, and has been the source of much error in that science. It is this opinion which has made Mr. Buchanan maintain that wages are not influenced by a rise or fall in the price of provisions, but solely by the demand and supply of labour; and that a tax on the wages of labour would not raise wages, because it would not alter the proportion of the demand of labourers to the supply.
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. Thus, if the value of money were to fall, the price of every commodity would rise, for each of the competitors would be willing to spend more money than before on its purchase; but though its price rose 10 or 20 per cent. if no more were bought than before, it would not, I apprehend, be admissible to say, that the variation in the price of the commodity was caused by the increased demand for it. Its natural price, its money cost of production, would be really altered by the altered value of money; and without any increase of demand, the price of the commodity would be naturally adjusted to that new value.
"We have seen," says M. Say, "that 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. Vol. ii. p. 26.
He afterwards says that the demand for gold having increased in a still greater proportion than the supply, since the discovery of the mines, "its price in goods, instead of falling in the proportion of ten to one, fell only in the proportion of four to one;" that is to say, instead of falling in proportion as its natural price had fallen, fell in proportion as the supply exceeded the demand.[48] "The value of every commodity rises always in a direct ratio to the demand, and in an inverse ratio to the supply."
The same opinion is expressed by the Earl of Lauderdale.
"With respect to the variations in value, of which every thing valuable is susceptible, if we could for a moment suppose that any substance possessed intrinsic and fixed value, so as to render an assumed quantity of it constantly, under all circumstances, of an equal value, then the degree of value of all things, ascertained by such a fixed standard, would vary according to the proportion betwixt the quantity of them, and the demand for them, and every commodity would of course be subject to a variation in its value, from four different circumstances.