For what, after all, is the distinction which Jevons wishes us to draw between a 'cause ' and a 'determining circumstance'? If he means that a 'cause' must be an ultimate mental thing, like desire or satisfaction, while a 'determining circumstance' is only a physical thing, like Labour; and if, as he admits, Labour in a large proportion of cases is the 'determining circumstance' of Value; then he ought frankly to have admitted that Value, or market price, was the result of the co-operation of two factors equally necessary, namely Labour and Utility, and not of Utility alone; whereas he has afterwards made his new system of Political Economy turn on the single factor of Utility; like a man who because when asked why he gave £100 for a piece of old china or an old master, he could justly reply because of the personal satisfaction, or 'utility,' he got out of it, should when asked why it was fourpence, and not a shilling, that he gave for a loaf of bread, deem it also a sufficient explanation to say, because of the amount of personal satisfaction which, being hungry, he got out of it.

And yet it is Jevons' own answer; for after much to-and-fro discussion, his conclusion is that Value depends solely on 'final utility.' Now the truth is, Jevons confounds the cause of Value in general, which of course is solely utility, or in general terms personal desire and satisfaction, and that alone, (otherwise no one would buy anything), with the cause of value in particular cases, or market price - quite a different matter. And this although it is precisely the problem of the cause or causes of particular values, which Political Economy has asked him to solve - not of the cause of Value in general.

The fact is, he did not see that no definite thing in this world, whether it be a market price or anything else, is ever the result of a single cause, but must always require at least two factors - a general and a limiting one, - and that it is only when the two are brought together that a definite something can arise; in the same way as it is only when a positive charge of electricity is brought into relation with a negative one, that a definite spark passes between them. And if this be so, it is evident that a definite market-price cannot be the result of any one thing, or degree of one thing, - whether it be the 'final' or any other degree of 'utility' or satisfaction, - but must be the result of a relation between that and some other thing. And the question now becomes why did Jevons stick so doggedly to his single cause - Utility? For if we can find an answer to this, it will give us an insight into the fallacy involved in his whole scientific procedure. He has himself given us the hint as to where to look for it, when he asks; - how can you ever compare the productive powers of a navvy, a carpenter, a schoolmaster, or a barrister, so as to reduce them to a common denomination of labour? And if you cannot, then the different values of things must, according to him, come out of the utility or satisfaction they yield, - only in different degrees.

But as the value of a thing is always the same at any given time in the same market, whereas the satisfaction which people get out of it at any particular time varies with every circumstance of their lives, - whether they are hungry or not hungry, whether they have just eaten their loaf or not yet eaten it, the amount of the commodity they have on hand or can look forward to having, the price they have to pay for it, the extent of their means, etc., - it follows that to get a common denominator in degrees of utility or satisfaction, as the basis of a definite market price, is even more hopeless than to get it out of the different kinds of labour. It is evident, then, that the different degrees of utility do not give us the second term of the relation of which we are in search. Now, if Jevons had said that the market price of an article was the relation between the mental or bodily disagreeableness to which one set of persons were put in producing the article, and the mental or bodily ■satisfaction which another set were to get out of it, not only would he have got the second term of the relation necessary, but both terms would have been of the same denomination; and his solution of the problem of value, accordingly, would have been in essence substantially true.

Or if he had made the price depend on the relation between the amount of labour that had to be put into an article, and the amount of labour to be got out of it - as out of a loaf of bread or ton of coals, - again he would have had two terms of the same denomination, and again would have been substantially right in his solution. In each case he would have got the two co-equal and co-essential causes, of the same denomination, which are necessary to produce a definite market-price. But by settling himself on one arm of the relation only, and excluding the other altogether as a 'cause,' not only did he set back the development of his science instead of advancing it, but he rendered all the deductions which he was about to draw from his solution futile. That he did intend to deduce other conclusions pertaining to the Science from it, is manifest; for at the outset of his work, he announces that his theory of Value 'is the keystone of the whole theory of Exchange, and of the principal problems of Political Economy.' But the deductions which he did not live long enough himself to draw, were drawn for him wholesale, as we shall see, by his pupil Bohm-Bawerk, as well as in limited directions by certain Economists of the English and American Schools - of which, more anon.