# Principles of Political Economy (J.S. Mill, 1871), vol. 1/Book III, Chapter I

BOOK III.
EXCHANGE.
CHAPTER I.
OF VALUE.
§ 1.The subject on which we are now about to enter fills so important and conspicuous a position in political economy, that in the apprehension of some thinkers its boundaries confound themselves with those of the science itself. One eminent writer has proposed as a name for Political Economy, "Catallactics," or the science of exchanges: by others it has been called the Science of Values. If these denominations had appeared to me logically correct, I must have placed the discussion of the elementary laws of value at the commencement of our inquiry, instead of postponing it to the Third Part; and the possibility of so long deferring it is alone a sufficient proof that this view of the nature of Political Economy is too confined. It is true that in the preceding Books we have not escaped the necessity of anticipating some small portion of the theory of Value, especially as to the value of labour and of land. It is nevertheless evident, that of the two great departments of Political Economy, the production of wealth and its distribution, the ​consideration of Value has to do with the latter alone; and with that, only so far as competition, and not usage or custom, is the distributing agency. The conditions and laws of Production would be the same as they are, if the arrangements of society did not depend on Exchange, or did not admit of it. Even in the present system of industrial life, in which employments are minutely subdivided, and all concerned in production depend for their remuneration on the price of a particular commodity, exchange is not the fundamental law of the distribution of the produce, no more than roads and carriages are the essential laws of motion, but merely a part of the machinery for effecting it. To confound these ideas, seems to me, not only a logical, but a practical blunder. It is a case of the error too common in political economy, of not distinguishing between necessities arising from the nature of things, and those created by social arrangements: an error, which appears to me to be at all times producing two opposite mischiefs; on the one hand, causing political economists to class the merely temporary truths of their subject among its permanent and universal laws; and on the other, leading many persons to mistake the permanent laws of Production (such as those on which the necessity is grounded of restraining population) for temporary accidents arising from the existing constitution of society—which those who would frame a new system of social arrangements, are at liberty to disregard.
In a state of society, however, in which the industrial system is entirely founded on purchase and sale, each individual, for the most part, living not on things in the production of which he himself bears a part, but on things obtained by a double exchange, a sale followed by a purchase—the question of Value is fundamental. Almost every speculation respecting the economical interests of a society thus constituted, implies some theory of Value: the smallest error on that subject infects with corresponding error all our other conclusions; and anything vague or misty in our conception ​of it, creates confusion and uncertainty in everything else. Happily, there is nothing in the laws of Value which remains for the present or any future writer to clear up; the theory of the subject is complete: the only difficulty to be overcome is that of so stating it as to solve by anticipation the chief perplexities which occur in applying it: and to do this, some minuteness of exposition, and considerable demands on the patience of the reader, are unavoidable. He will be amply repaid, however (if a stranger to these inquiries), by the ease and rapidity with which a thorough understanding of this subject will enable him to fathom most of the remaining questions of political economy.
§ 2.We must begin by settling our phraseology. Adam Smith, in a passage often quoted, has touched upon the most obvious ambiguity of the word value; which, in one of its senses, signifies usefulness, in another, power of purchasing; in his own language, value in use and value in exchange. But (as Mr. De Quincey has remarked) in illustrating this double meaning, Adam Smith has himself fallen into another ambiguity. Things (he says) which have the greatest value in use have often little or no value in exchange; which is true, since that which can be obtained without labour or sacrifice will command no price, however useful or needful it may be. But he proceeds to add, that things which have the greatest value in exchange, as a diamond for example, may have little or no value in use. This is employing the word use, not in the sense in which political economy is concerned with it, but in that other sense in which use is opposed to pleasure. Political economy has nothing to do with the comparative estimation of different uses in the judgment of a philosopher or of a moralist. The use of a thing, in political economy, means its capacity to satisfy a desire, or serve a purpose. Diamonds have this capacity in a high degree, and unless they had it, would not bear any price. Value in use, or as Mr. De Quincey calls it, teleologic value, ​is the extreme limit of value in exchange. The exchange value of a thing may fall short, to any amount, of its value in use; but that it can ever exceed the value in use, implies a contradiction; it supposes that persons will give, to possess a thing, more than the utmost value which they themselves put upon it as a means of gratifying their inclinations.
The word Value, when used without adjunct, always means, in political economy, value in exchange; or as it has been called by Adam Smith and his successors, exchangeable value, a phrase which no amount of authority that can be quoted for it can make other than bad English. Mr. De Quincey substitutes the term Exchange Value, which is unexceptionable.
Exchange value requires to be distinguished from Price. The words Value and Price were used as synonymous by the early political economists, and are not always discriminated even by Ricardo. But the most accurate modern writers, to avoid the wasteful expenditure of two good scientific terms on a single idea, have employed Price to express the value of a thing in relation to money; the quantity of money for which it will exchange. By the price of a thing, therefore, we shall henceforth understand its value in money; by the value, or exchange value of a thing, its general power of purchasing; the command which its possession gives over purchaseable commodities in general.
§ 3.But here a fresh demand for explanation presents itself. What is meant by command over commodities in general? The same thing exchanges for a great quantity of some commodities, and for a very small quantity of others. A suit of clothes exchanges for a great quantity of bread, and for a very small quantity of precious stones. The value of a thing in exchange for some commodities may be rising, for others falling. A coat may exchange for less bread this year than last, if the harvest has been bad, but for more glass or iron, if a tax has been taken off those commodities, or an ​improvement made in their manufacture. Has the value of the coat, under these circumstances, fallen or risen? It is impossible to say: all that can be said is, that it has fallen in relation to one thing, and risen in respect to another. But there is another case, in which no one would have any hesitation in saying what sort of change had taken place in the value of the coat: namely, if the cause in which the disturbance of exchange values originated, was something directly affecting the coat itself, and not the bread or the glass. Suppose, for example, that an invention had been made in machinery, by which broadcloth could be woven at half the former cost. The effect of this would be to lower the value of a coat, and if lowered by this cause, it would be lowered not in relation to bread only or to glass only, but to all purchaseable things, except such as happened to be affected at the very time by a similar depressing cause. We should therefore say, that there had been a fall in the exchange value or general purchasing power of a coat. The idea of general exchange value originates in the fact, that there really are causes which tend to alter the value of a thing in exchange for things generally, that is, for all things which are not themselves acted upon by causes of similar tendency.
In considering exchange value scientifically, it is expedient to abstract from it all causes except those which originate in the very commodity under consideration. Those which originate in the commodities with which we compare it, affect its value in relation to those commodities; but those which originate in itself, affect its value in relation to all commodities. In order the more completely to confine our attention to these last, it is convenient to assume that all commodities but the one in question remain invariable in their relative values. When we are considering the causes which raise or lower the value of corn, we suppose that woollens, silks, cutlery, sugar, timber, &c., while varying in their power of purchasing corn, remain constant in the ​proportions in which they exchange for one another. On this assumption, any one of them may be taken as a representative of all the rest; since in whatever manner corn varies in value with respect to any one commodity, it varies in the same manner and degree with respect to every other; and the upward or downward movement of its value estimated in some one thing, is all that need be considered. Its money value, therefore, or price, will represent as well as anything else its general exchange value, or purchasing power; and from an obvious convenience, will often be employed by us in that representative character; with the proviso that money itself do not vary in its general purchasing power, but that the prices of all things, other than that which we happen to be considering, remain unaltered.
§ 4.The distinction between Value and Price, as we have now defined them, is so obvious, as scarcely to seem in need of any illustration. But in political economy the greatest errors arise from overlooking the most obvious truths. Simple as this distinction is, it has consequences with which a reader unacquainted with the subject would do well to begin early by making himself thoroughly familiar. The following is one of the principal. There is such a thing as a general rise of prices. All commodities may rise in their money price. But there cannot be a general rise of values. It is a contradiction in terms. A can only rise in value by exchanging for a greater quantity of B and C; in which case these must exchange for a smaller quantity of A. All things cannot rise relatively to one another. If one-half of the commodities in the market rise in exchange value, the very terms imply a fall of the other half; and reciprocally, the fall implies a rise. Things which are exchanged for one another can no more all fall, or all rise, than a dozen runners can each outrun all the rest, or a hundred trees all overtop one another. Simple as this truth is, we shall presently see that it is lost sight of in some of the most accredited doctrines ​both of theorists and of what are called practical men. And as a first specimen, we may instance the great importance attached in the imagination of most people to a rise or fall of general prices. Because when the price of any one commodity rises, the circumstance usually indicates a rise of its value, people have an indistinct feeling when all prices rise, as if all things simultaneously had risen in value, and all the possessors had become enriched. That the money prices of all things should rise or fall, provided they all rise or fall equally, is in itself, and apart from existing contracts, of no consequence. It affects nobody's wages, profits, or rent. Every one gets more money in the one case and less in the other; but of all that is to be bought with money they get neither more nor less than before. It makes no other difference than that of using more or fewer counter to reckon by. The only thing which in this case is really altered in value is money; and the only persons who either gain or lose are the holders of money, or those who have to receive or to pay fixed sums of it. There is a difference to annuitants and to creditors the one way, and to those who are burthened with annuities, or with debts, the contrary way. There is a disturbance, in short, of fixed money contracts; and this is an evil, whether it takes place in the debtor's favour or in the creditor's. But as to future transactions there is no difference to any one. Let it therefore be remembered (and occasions will often arise for calling it to mind) that a general rise or a general fall of values is a contradiction; and that a general rise or a general fall of prices is merely tantamount to an alteration in the value of money, and is a matter of complete indifference, save in so far as it affects existing contracts for receiving and paying fixed pecuniary amounts, and (it must be added) as it affects the interests of the producers of money.
§ 5.Before commencing the inquiry into the laws of value and price, I have one further observation to make. I ​must give warning, once for all, that the cases I contemplate are those in which values and prices are determined by competition alone. In so far only as they are thus determined, can they be reduced to any assignable law. The buyers must be supposed as studious to buy cheap, as the sellers to sell dear. The values and prices, therefore, to which our conclusions apply, are mercantile values and prices; such prices as are quoted in price-currents; prices in the wholesale markets, in which buying as well as selling is a matter of business; in which the buyers take pains to know, and generally do know, the lowest price at which an article of a given quality can be obtained; and in which, therefore, the axiom is true, that there cannot be for the same article, of the same quality, two prices in the same market. Our propositions will be true in a much more qualified sense, of retail prices; the prices paid in shops for articles of personal consumption. For such things there often are not merely two, but many prices, in different shops, or even in the same shop; habit and accident having as much to do in the matter as general causes. Purchases for private use, even by people in business, are not always made on business principles: the feelings which come into play in the operation of getting, and in that of spending their income, are often extremely different. Either from indolence, or carelessness, or because people think it fine to pay and ask no questions, three-fourths of those who can afford it give much higher prices than necessary for the things they consume; while the poor often do the same from ignorance and defect of judgment, want of time for searching and making inquiry, and not unfrequently from coercion, open or disguised. For these reasons, retail prices do not follow with all the regularity which might be expected, the action of the causes which determine wholesale prices. The influence of those causes is ultimately felt in the retail markets, and is the real source of such variations in retail prices as are of a general and permanent character. But there is no regular or exact correspondence. Shoes of ​equally good quality are sold in different shops at prices which differ considerably; and the price of leather may fall without causing the richer class of buyers to pay less for shoes. Nevertheless, shoes do sometimes fall in price; and when they do, the cause is always some such general circumstance as the cheapening of leather: and when leather is cheapened, even if no difference shows itself in shops frequented by rich people, the artizan and the labourer generally get their shoes cheaper, and there is a visible diminution in the contract prices at which shoes are delivered for the supply of a workhouse or of a regiment In all reasoning about prices, the proviso must be understood, "supposing all parties to take care of their own interest."
Inattention to these distinctions has led to improper applications of the abstract principles of political economy, and still often to an undue discrediting of those principles, through their being compared with a different sort of facts from those which they contemplate, or which can fairly be expected to accord with them.