Jevons was a British economist (1835-1882), who is considered, along with Carl Menger and M.-E.-L. Walras, a co-founder of marginalism and theory of utility. Jevons is the author of the book “The Theory of Political Economy”, 1871, in which he devised the concept of marginal utility, from an additive and separable utility function, although it was not measurable on cardinal terms. These studies were possible thanks to Johann H. von Thünen’s works, who was the first economist to use the word “marginal”, which meaning Jevons adopted in his works using the term “final”. He is also considered as a precursor of Econometrics for his work on business cycle, index numbers and moving averages, topics on which he used his extensive knowledge of mathematics.

Although his works on marginal utility are considered pioneer during the marginal revolution, and important for the development of neoclassical economics, Jevons considered there would be only one possible solution when considering barter exchange. However, there are infinite solutions, as was demonstrated later on by Francis Y. Edgeworth, whose indifference curves are based on Jevons’ earlier work.

Carl Menger, was an Austrian economist (1840-1921), who is considered to be, along with W. S. Jevons and M.-E.-L. Walras, a co-founder of marginalism and of the theory of utility, and was also founder of the Austrian School, where his main followers Wieser and Böhm-Bawerk were his disciples. In his “Principles of Economics”, 1871, Menger attacked as incorrect the labor theory of value, expressing his view that the factor determining the value of a good is not the amount of work nor other goods needed to produce it, but the importance we place on the basis of the satisfaction we believe that it can offer.

Karl Marx was a German politician, philosopher, economist, and sociologist (1818-1883). He studied law and it was in his famous “Thesis on Feuerbach”, where he formulated the proposition that the philosopher must not be contented with the contemplation of life, but must contribute in changing it. Marx’s early contributions to Economics were as editor of the “Rheinische Zeitung”, whose radical content made him face Prussian authorities. In 1847, along with Friedrich Engels, he wrote the Communist Manifesto, true synthesis of his thinking. However, his most important work is “Capital: Critique of Political Economy”.

Although he is the one who gave name to the Classical school of Economics, and he might not be considered a part of it because of his different conclusions on theory of value, we consider he should be considered part of this school, mainly because he worked on the same issues as other classical authors.

Adam Smith was born in 1723. His father was a lawyer and civil servant, and during his years as a moral philosophy student at the University of Glasgow, Adam Smith developed an increasing interest in liberty, reason and free speech. He then went on to continue his studies at Oxford, where he started writing about the low quality of education in English universities. Later, he taught at Edinburgh and the University of Glasgow, where he would end up occupying the position of rector until his death, in 1790.

During his lifetime, Smith met well known philosophers such as David Hume and Voltaire and other intellectual leaders such as Benjamin Franklin, François Quesnay or A.-R.-J. Turgot, who influenced his work, helping him become the first great economist of the Classical school of economics.

“The Wealth of Nations,” which took twelve long years to write, finally published in 1776, is the foundation of modern economics. It was basically against prevailing mercantilist theories, introducing the importance of the principle of division of labour and defending free trade. Basically, Smith understood that the satisfaction of individual self-interest, limited by that of the others was the best means to achieve the greatest good for the greatest number of people. However, he supported the State’s action in justice, education, health, and in all those enterprises that private initiative was unable to address.