O N T H E D I F F E R E N C E B E T W E E N A M E A S U R E
A N D A C A U S E O F V A L U E .
ANY one who takes the trouble of minutely examining the writings of the most celebrated political economists will be astonished, not only at the looseness of expression, but at the vagueness of design by which they are too frequently distinguished. It is often far from being manifest, what is the precise doctrine or proposition they are intending to support, or to overthrow; or rather, it is evident that they themselves have not succeeded in defining it clearly to their own understandings.
No department of political economy has suffered more from this indefiniteness of purpose, and ambiguity of language, than that which is  occupied with investigating the measures and causes of value. It would seem, on a first view, that the ideas of measuring and causing value were sufficiently distinct to escape all danger of being confounded; yet it is remarkable, that both the ideas themselves, and the terms by which they are expressed, have been mixed and interchanged and substituted, with an apparently total unconsciousness of any difference existing between them.
The author of the Templars Dialogues on Political Economy is the only writer who appears to me to have been fully aware of this confusion of two separate and distinct ideas*. He traces it partly to an ambiguity in the word determine. The word determine, says he, may be taken subjectively for what determines x in relation to our knowledge, or objectively, for what determines x in relation to itself.  Thus if I were to ask, What determined the length of the race course ?’ and the answer were, The convenience of the spectators, who could not have seen the horses at a greater distance; or, The choice of the subscribers; then it is plain, that by the word determined,’ I was understood to mean determined objectively, in relation to the existence of the object; in other words, what caused the race-course to be this length rather than another length: but if the answer were, An actual admeasurement, it would then be plain, that by the word determined, I had been understood to mean determined subjectively, i. e. in relation to our knowledge; what ascertained it* ?
The writer just quoted is wrong, however, in supposing Mr. Ricardo to be free from ambiguity in this point. A very cursory inspection of the Principles of Political Economy and Taxation will show, that he has fallen into the same confusion as other economists; and it is astonishing to find the author of the Dia-logues asserting, that Mr. Ricardo did not propose his principle of value (namely, the quantity of labour) as the measure of value. The fact is, that he sometimes speaks of it as the cause, and sometimes as the measure, in such a way as proves that he had not attained to any distinct conception of the difference between the two ideas.
Thus in the first section of his book he accuses Adam Smith of erecting the labour, which a commodity will command, into a standard measure, instead of the labour bestowed on its production, the latter of which he asserts to be, under many circumstances, an invariable standard, indicating correctly the variations of other things*. Farther on he speaks of estimating food and necessaries by the quantity of labour necssary [sic] for their production; contrasting it with measuring them by the quantity of labour for which they will exchange†.
In the second section, after speaking of la-bour as being the foundation of all value, he adopts in a note the language of Adam Smith, which designates labour as the real measure of the exchangeable value of all commodities*.
In another chapter of his work he is still more explicit.
A franc, says he, is not a measure of value for any thing, but for a quantity of the same metal of which francs are made, unless francs and the thing to be measured can be referred to some other measure, which is common to both. This I think they can be, for they are both the result of labour ; and, therefore, labour is a common measure, by which their real as well as their relative value may be estimated†.
And to support this doctrine he cites a passage from M. Destutt de Tracy, the scope of which is to show that labour is the cause of value. Surely nothing can more decisively prove a confusion of ideas on this point than adducing a passage, which asserts labour to be  the cause of value, in confirmation of a proposition that it is the measure of value.
Mr. Malthus, who has himself fallen into the same confusion of ideas and terms, is sufficiently justified by these passages in attributing to Mr. Ricardo the act of bringing forward his principle as a measure. That Mr. Ricardo has more frequently spoken of it as a cause of value, only proves that he has deviated into inconsistencies. How the author of the Dialogues could be led to maintain, in the face of these passages, that Mr. Ricardo never dreamed of offering it as a standard or measure of value, it is difficult to imagine.
It will possibly be urged by the admirers of Mr. Ricardo, in order to defend him from the charge of inconsistency or ambiguity of language, that if quantity of labour is truly the sole cause of value, then it must also be a correct measure or criterion of value ; and as one of these circumstances necessarily follows the other, it is indifferent in which capacity we speak of it.
 It is certainly true, that, provided quantity of labour were the sole cause of value, we should always be able to deduce the value of two commodities from a knowledge of the quantities of labour which they respectively required to produce them; and in this sense, quantity of labour would be at once the cause and the measure of value. But even under these circumstances, an author would not be justified in an indiscriminate use of the terms; nor could he fall into such an error, had he a distinct apprehension of the difference between the two ideas.
It would by no means follow, however, from quantity of labour being the cause of value, that it would be of any service as a measure. On this point we may adopt the language of the author of the Dialogues: If it had been proposed as a measure of value, we might justly demand that it should be ready and easy of application; but it is manifestly not so; for the quantity of labour employed in producing A, could not in many cases (as Mr. Malthus  truly objects) be ascertained without considerable difficulty:’ in most cases, indeed, it could not be ascertained at all. A measure of value, however, which cannot be practically applied, is worthless*.
It was probably some obscure and undefined impression of this truth, which, when Mr. Ricardo deliberately set himself to treat on the subject of a measure of value, influenced him to speak, not of labour itself in that capacity, but of a commodity produced by an invariable quantity of labour. If the quantity of producing labour really determines the value of commodities, it seems on a first view useless to require for a measure an object of which the producing labour is invariable, when we may have recourse to the labour itself. But Mr. Ricardo probably perceived, that a knowledge of the quantity of producing labour in objects would be in most cases difficult of attainment, and therefore betook himself to the considera-tion of a commodity in which a definite portion of it was embodied*.
All that is really meant by a measure of value we have already seen, and what is implied by a cause of value will be examined in the following chapter. The object of the preceding brief discussion is not to consider the nature of either, but merely to show the essential distinction between the ideas which they involve.