A has spades, and B has oats, to dispose of; and each wishes to get the article belonging to the other. Will A give one spade for one bushel of oats, or for two? Will B give two bushels of oats for one spade? That depends upon how strong a desire A has for oats; the intensity of his demand may induce him to give two spades for one bushel. But the exchange also depends upon B. If he has no great need for spades, and A has a strong desire for oats, B will get more spades for oats than otherwise, possibly two spades for one bushel of oats; that is, oats will have a larger exchange value. If, on the other hand, A cares less for oats than B does for spades, then the exchange will result in an increased value of spades relatively to oats. When two commodities exchange against each other, their exchange values will depend entirely upon the relative intensity of the demand [pg 394] on each side for the other commodity. And this simple form of the statement of reciprocal demand and supply is also the law of international values.
If instead of spades and oats we substitute iron and corn, and let the trade be between England and the United States, the quantity of corn required to buy a given quantity of iron will depend upon the relative demands of England for corn and of the United States for iron. Something may cut off England's demand for our breadstuffs, and they will then have a less exchange value relatively to iron (if we keep up our demand), and their prices will fall. But if, on the other hand, England has poor harvests, and consequently a great demand for corn, and if our demand for iron is not excessive at the same time, then our breadstuffs will rise in value. And this was precisely what happened from 1877 to 1879. Now, in the above illustration of corn and iron, how can we know whether or not x bushels of corn (the produce of 100 days' labor in the United States) will exchange for exactly y tons of English iron? That, again, will depend upon the reciprocal demands of the two countries for corn and iron respectively. Moreover, it will have been already observed that the ratio of exchange is not capable of being ascertained exactly, since it varies with changing conditions, namely, the desires of the people of the two countries, together with their means of purchase.
But yet these variations are capable of ascertainment as regards their extreme limits. The reciprocal demand can not carry the exchange value in either country beyond the line set by the cost of production of the article. For instance, an urgent need in England for corn (if the United States has a light demand for English iron) can not carry the ratio of exchange to a point such that England will offer so much more than 150 days' labor in iron for x bushels of American corn that it will go beyond 200 days' labor in iron. It will be seen at once, then, if that were the case, that England would produce the corn herself; and that she would then have no gain whatever from the trade. The ratio of exchange will thus be limited by the reciprocal demand on one side to the cost of production (200 days' labor) of English corn. On the other hand, if the supposition were reversed, and the United States had a great demand for iron, but England had little need for our corn, then we would not offer more than 125 days' labor of corn for y tons of iron, because for that expenditure of labor we could produce the iron ourselves.
In the above examples we have considered the case of a trade in corn and iron only. If corn were to typify all our goods wanted by England, and iron all English goods wanted by the United States, the conclusions would be exactly the [pg 395] same. The ratios of a myriad of things, each governed by its particular reciprocal demand, exchanging against each other, give a general result by which the goods sent out exchange against the goods brought back at such rates as are fixed by the reciprocal demands acting on all the goods. Goods are payments for goods; the ratio of exchange depends on reciprocal demand and supply. If we now add more countries to the example, we simply increase the number of persons (although in different countries) wanting our goods, as set off against our demands for the goods of this greater number of persons. If France, Germany, and England all want our corn, we must have some demand for the goods of France, Germany, and England also; and the same law of reciprocal demand gives the ratio of interchange. That this explanation is consistent with the facts is to be seen when we notice how eagerly the exporters of American staples watch the conditions which increase or diminish the foreign demand for these commodities, looking at them as the causes which directly affect their exchange value, or price.
When cost of carriage is added, it will increase the price of corn to England and of iron to the United States. But, as every one knows, an increase of price affects the demand; and, as the demand on each side is affected, a new ratio of exchange will finally be reached consistent with the strength of desires on each side. Who, therefore, will pay the most of the cost of carriage England or the United States? That will, again, depend on whether England has the greatest relative demand for American goods, as compared with the demand of the United States for English goods.
No absolute rule, therefore, can be laid down for the division of the cost, no more than for the division of the advantage; and it does not follow that, in whatever ratio the one is divided, the other will be divided in the same. It is impossible to say, if the cost of carriage could be annihilated, whether the producing or the importing country would be most benefited. This would depend on the play of international demand.
Cost of carriage has one effect more. But for it, every commodity would (if trade be supposed free) be either regularly imported or regularly exported. A country would make nothing for itself which it did not also make for other countries. But in consequence of cost of carriage there are many things, especially bulky articles, which every, or almost [pg 396] every, country produces within itself. After exporting the things in which it can employ itself most advantageously, and importing those in which it is under the greatest disadvantage, there are many lying between, of which the relative cost of production in that and in other countries differs so little that the cost of carriage would absorb more than the whole saving in cost of production which would be obtained by importing one and exporting another. This is the case with numerous commodities of common consumption, including the coarser qualities of many articles of food and manufacture, of which the finer kinds are the subject of extensive international traffic.
§ 3. —As illustrated by trade in cloth and linen between England and Germany.
Mr. Mill still further illustrates the operation of the law of reciprocal demand by the case of a trade between England and Germany in cloth and linen, as follows: