William Petty: biography of this philosopher and economist

William Petty was an English philosopher, physician, economist and statistician who made important contributions to his country, especially being among the first to link demography, economics and public health.

Coming from a rather humble family, a series of fortuitous and fortunate events made anyone who was the son of a simple weaver a rich and prestigious landowner, in addition to receiving the title of gentleman.

He was an English parliamentarian and a friend of Oliver Cromwell, head of the Republican Commonwealth of England. Below we will see in more depth the life of this researcher and his contributions to the study of population and the economy, through a biography of William Petty.

    Brief biography of William Petty

    From humble origins to becoming a major English landowner. You could say that William Petty’s life goes from beginning to endUntil then, especially since it was his turn to experience rather turbulent times in his native England, halfway between absolute monarchy, failed republic and prosperous English monarchical constitutionalism.

    His economic ideas helped lead great figures such as Karl Marx or Adam Smith to expound his popular theories on capitalism, both for good and for evil. Marx came to see William Petty as such an important figure that he even claimed that Petty was the founder of modern political economy.. Either way, this 17th century character was really well advanced in his time, which is why he is so well known today.

      Childhood and training

      William Petty was born in Ramsey County, England, May 23, 1623. He was brought up in a very humble family, because his father was a weaver. He spent his early years studying at his hometown high school and quickly began to stand out for his intelligence and ability.

      But despite his excellent studies, he could not avoid working as a child. Her family was still in need and any home pay was welcome. so he enlisted as a cabin boy on a boat but had the misfortune of being moored off the coast of France by his comrades..

      However, far from intimidating him, he saw his arrival in France as an opportunity and decided to write to the Jesuits at the University of Caen in Normandy. The letter, written in perfect Latin, attracted so much attention that the institution immediately admitted it. On his return to England be able to study philosophy, geometry and astronomy at the age of 17 at the prestigious Oxford.

      At the outbreak of the English Civil War, in which Kings Charles II and James II clashed against Parliament and eventually a republic was formed under Oliver Cromwell’s government, Petty fled to Holland. There he would have the opportunity to study medicine, a science that would serve him well by applying it to his subsequent studies in economics. When finishing his studies he walked towards Paris, cosmopolitan city in which the philosopher Thomas Hobbes would know.

      At the age of 24, he returned to London. Despite his youth, his intelligence and his studies have earned him to become a hole between the intellectuality of their time. From there he managed to become a professor at the prestigious Oxford, the same place where he had studied.

      Cromwelll’s friend

      The English invasion of Ireland was to become a turning point in Petty’s career. During this war enlisted as a medic in the military and had the opportunity to report to Oliver Cromwell himself., With whom he has established a very good friendship. Thanks to this, after conquering the Emerald Isle, Cromwell commissioned Petty to draw various topographical maps of the new properties of the Commonwealth of England.

      So from 1655-1658 Petty he traveled across Ireland to produce maps, rewarded with vast tracts of land as payment. Thus, William Petty, the childhood had been that of a poor weaver’s son and abandoned in his youth in lands lost in the hands of the French God who had become a rich landowner. Becoming the figure of Cromwell earned him great reputation and properties.

      last years

      William Petty no longer had financial problems and even became a member of the English Parliament, in addition to being one of the founders of the Royal Society. From now on he devoted himself to the complete study of the different sciences, writing several books in which he expounded his theories.. He died in London on December 16, 1687, holding the title of Sir for a lifetime of great contributions to his native England.

        Contributions to the economy

        One of the geniuses that William Petty had and is known for is the fact that he brought the same methods and knowledge of medicine into the study of economics. He believes that each economic element should be considered as a whole, Use more mathematical, statistical and scientific tools in general to solve problems that harm national wealth. It is often thought that he deviated a lot from the dominant commercialism of his time. Among his contributions we have the following.

        Theory of value

        William Petty considered that all economic exchange was subject to rules he considered natural, to which any opposition is unnecessary. He believed that sooner or later the prices of products eventually return to their natural level.. According to Petty, the origin of value is in the work. He differentiated two types of values ​​for each product:

        On the one hand, we have the natural value, which refers to the internal value of each product, that is, what the product costs to produce on its own. In order to be able to calculate it, it is necessary to take into account the work required to produce it and calculate the productivity, taking into account two different measures: the land and the work itself. In his own words, you could say that work is the father of wealth and the earth is its mother.

        The second value is politics. This is the market value, which always depends on a multitude of factors, not as simple and easy to understand as the production and labor required to produce the product. These factors that make up political value are foreign to natural laws, depending on the subjectivity of the traders themselves, the demand, supply and needs of the consumers themselves.


        Petty developed a theory to explain what type of taxes and fees were appropriate for being able to generate social wealth. According to his theory, each person should contribute according to the property and income earnedUnderstanding that it was not fair to ask the richest for taxes that meant no effort when these same amounts were abusive for the poorest classes. Despite this, he knew that the majority did not want to pay and that he was trying to get rid of his obligations.

        Petty himself believed that taxes should not be excessive, too high to cause people to tighten their belts and try to save, as it would hurt national trade. He believed that the taxes would be beneficial as long as the proceeds were invested in domestic products., Do not feed the free pockets of the elites and the wealthy classes.

        Petty’s Law

        Petty’s Law, later renamed Petty-Clark’s Law thanks to contributions from Colin Clark, is an economic law that suggests that as technical advances reduce transport costs, the market for non-agricultural products should develop. This means that the labor force engaged in agriculture must readjust and move towards non-agricultural activities, leaving behind mainly agricultural production societies towards more diversified societies, in which other economic activities are carried out. .

        As the means of transporting agricultural products improve, the process requires less labor. This leads to structural changes in society, as those who have been involved in this process lose their jobs and are forced to look for work in the cities. This means that the life in the countryside is gradually abandoned and that it will end up in urban areas, where artisanal work and industry, in addition to the service sector.

        With contributions from Clark it was concluded that one of the main modes of manifestation of economic progress is the continuous transfer of labor from the primary sector to the secondary sector and, subsequently, to the tertiary sector.. In other words, as we move from the agricultural sector to the industrial sector and then to the services sector, according to the ideas of Petty and Clark himself, economic progress is being made.


        Petty had a great passion for demography and often couldn’t help but relate it to economics. It was he and statistician John Graunt who created the UK’s first life tables., Considered the beginning of modern demography. He believed that people brought value to the economy and that population growth should be the basis for economic improvement. According to him, the more people there are, the more work there will be and the more wealth there will be.


        Also linked to his interest in population growth and combined with his medical training, William Petty considers it essential to improve health. He felt that it was necessary to create an English health system that would guarantee the good health of the citizens, preventing them from contracting contagious diseases. that they have decimated the population and that it has reduced the economic productivity of the nation. This is why he proposes the creation of a Health Council in London, in addition to creating a hospital in which the training of English doctors is developing.

        Bibliographical references:

        • Petty, W. (1662) A Treatise on Taxes and Contributions (later editions: 1667, 1679, 1685, etc.)
        • Petty, W. (1682) An essay on the multiplication of mankind.
        • Aspromourgos, Tony (1988) “The life of William Petty in relation to his economy” in History of Political Economy 20: 337-356.
        • Routh, Guy (1989) The Origin of Economic Ideas. London: Macmillan.

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