William Stanley Jevons
William Stanley Jevons was an English economist and logician.
Irving Fisher described Jevons's book A General Mathematical Theory of Political Economy as the start of the mathematical method in economics. It made the case that economics, as a science concerned with quantities, is necessarily mathematical. In so doing, it expounded upon the "final" utility theory of value. Jevons' work, along with similar discoveries made by Carl Menger in Vienna and by Léon Walras in Switzerland, marked the opening of a new period in the history of economic thought. Jevons's contribution to the marginal revolution in economics in the late 19th century established his reputation as a leading political economist and logician of the time.
Jevons broke off his studies of the natural sciences in London in 1854 to work as an assayer in Sydney, where he acquired an interest in political economy. Returning to the UK in 1859, he published General Mathematical Theory of Political Economy in 1862, outlining the marginal utility theory of value, and A Serious Fall in the Value of Gold in 1863. For Jevons, the utility or value to a consumer of an additional unit of a product is inversely related to the number of units of that product he already owns, at least beyond some critical quantity.
Jevons received public recognition for his work on The Coal Question, in which he called attention to the gradual exhaustion of Britain's coal supplies and also put forth the view that increases in energy production efficiency leads to more, not less, consumption. This view is known today as the Jevons paradox, named after him. Due to this particular work, Jevons is regarded today as the first economist of some standing to develop an 'ecological' perspective on the economy.
The most important of his works on logic and scientific methods is his Principles of Science, as well as The Theory of Political Economy and The State in Relation to Labour. Among his inventions was the logic piano, a mechanical computer.
Background
Jevons was born in Liverpool, Lancashire, England. His father, Thomas Jevons, was an iron merchant who wrote about legal and economic subjects as well. His mother Mary Anne Jevons was the daughter of William Roscoe. At the age of fifteen he was sent to London to attend the University College School. Around this time, he seemed to have formed the belief that he was capable of important achievements as a thinker. Towards the end of 1853, after having spent two years at University College, where his favourite subjects were chemistry and botany, he received an offer as metallurgical assayer for the new mint in Australia. The idea of leaving the UK was distasteful, but pecuniary considerations had, in consequence of the failure of his father's firm in 1847, become of vital importance, and he accepted the post.Jevons left the UK for Sydney in June 1854 to take up a role as an Assayer at the Mint. Jevons lived with his colleague and his wife first at Church Hill, then in Annangrove at Petersham and at Double Bay before returning to England. In letters to his family he described his life, took photographs and produced a social map of Sydney. Jevons returned to England via America five years later.
He resigned his appointment, and in the autumn of 1859 re-entered the University College London as a student. He was granted B.A. and M.A. degrees from the University of London. He now gave his principal attention to the moral sciences, but his interest in natural science was by no means exhausted: throughout his life he continued to write occasional papers on scientific subjects, and his knowledge of the physical sciences greatly contributed to the success of his chief logical work, The Principles of Science. Not long after taking his M.A. degree, Jevons obtained a post as tutor at Owens College, Manchester.
In 1866, he was elected professor of logic and mental and moral philosophy and Cobden professor of political economy at Owens College. In the same year he was elected to Membership of the Manchester Literary and Philosophical Society on 13 November 1866.
Theory of utility
Jevons arrived quite early in his career at the doctrines that constituted his most characteristic and original contributions to economics and logic. The theory of utility, which became the keynote of his general theory of political economy, was practically formulated in a letter written in 1860; and the germ of his logical principles of the substitution of similars may be found in the view which he propounded in another letter written in 1861, that "philosophy would be found to consist solely in pointing out the likeness of things." The theory of utility above referred to, namely, that the degree of utility of a commodity is some continuous mathematical function of the quantity of the commodity available, together with the implied doctrine that economics is essentially a mathematical science, took more definite form in a paper on "A General Mathematical Theory of Political Economy", written for the British Association in 1862. This paper does not appear to have attracted much attention either in 1862 or on its publication four years later in the Journal of the Statistical Society; and it was not till 1871, when the Theory of Political Economy appeared, that Jevons set forth his doctrines in a fully developed form.It was not until after the publication of this work that Jevons became acquainted with the applications of mathematics to political economy made by earlier writers, notably Antoine Augustin Cournot and H.H. Gossen. The theory of utility was at about 1870 being independently developed on somewhat similar lines by Carl Menger in Austria and Léon Walras in Switzerland. As regards the discovery of the connection between value in exchange and final utility, the priority belongs to Gossen, but this in no way detracts from the great importance of the service which Jevons rendered to British economics by his fresh discovery of the principle, and by the way in which he ultimately forced it into notice. In his reaction from the prevailing view he sometimes expressed himself without due qualification: the declaration, for instance, made at the commencement of the Theory of Political Economy, that value depends entirely upon utility, lent itself to misinterpretation. But a certain exaggeration of emphasis may be pardoned in a writer seeking to attract the attention of an indifferent public. The Neoclassical Revolution, which would reshape economics, had been started.
Jevons did not explicitly distinguish between the concepts of ordinal and cardinal utility. Cardinal utility allows the relative magnitude of utilities to be discussed, while ordinal utility only implies that goods can be compared and ranked according to which good provided the most utility. Although Jevons predated the debate about ordinality or cardinality of utility, his mathematics required the use of cardinal utility functions. For example, in "The Theory of Political Economy", Chapter II, the subsection on "Theory of Dimensions of Economic Quantities", Jevons makes the statement that "In the first place, pleasure and pain must be regarded as measured upon the same scale, and as having, therefore, the same dimensions, being quantities of the same kind, which can be added and subtracted...." Speaking of measurement, addition and subtraction requires cardinality, as does Jevons's heavy use of integral calculus. Cardinality does not imply direct measurability, in which Jevons did not believe.
Practical economics
It was not, however, as a theorist dealing with the fundamental data of economic science, but as a writer on practical economic questions, that Jevons first received general recognition. A Serious Fall in the Value of Gold and The Coal Question placed him in the front rank as a writer on applied economics and statistics; and he would be remembered as one of the leading economists of the 19th century even had his Theory of Political Economy never been written. His economic works include Money and the Mechanism of Exchange written in a popular style, and descriptive rather than theoretical; a Primer on Political Economy ; The State in Relation to Labour, and two works published after his death, Methods of Social Reform" and "Investigations in Currency and Finance, containing papers that had appeared separately during his lifetime. The last-named volume contains Jevons's speculations on the connection between commercial crises and sunspots. He was engaged at the time of his death upon the preparation of a large treatise on economics and had drawn up a table of contents and completed some chapters and parts of chapters. This fragment was published in 1905 under the title of The Principles of Economics: a fragment of a treatise on the industrial mechanism of society, and other papers.In The Coal Question, Jevons covered a breadth of concepts on energy depletion that have recently been revisited by writers covering the subject of peak oil. For example, Jevons explained that improving energy efficiency typically reduced energy costs and thereby increased rather than decreased energy use, an effect now known as the Jevons paradox. The Coal Question remains a paradigmatic study of resource depletion theory. Jevons's son, H. Stanley Jevons, published an 800-page follow-up study in 1915 in which the difficulties of estimating recoverable reserves of a theoretically finite resource are discussed in detail.
In 1875, Jevons read a paper On the influence of the sun-spot period upon the price of corn at a meeting of the British Association for the Advancement of Science. This captured the attention of the media and led to the coining of the word sunspottery for claims of links between various cyclic events and sun-spots. In a later work, "Commercial Crises and Sun-Spots", Jevons analyzed business cycles, proposing that crises in the economy might not be random events, but might be based on discernible prior causes. To clarify the concept, he presented a statistical study relating business cycles with sunspots. His reasoning was that sunspots affected the weather, which, in turn, affected crops. Crop changes could then be expected to cause economic changes. Subsequent studies have found that sunny weather has a small but significant positive impact on stock returns, probably due to its impact on traders' moods.