The three-sector theory is an economic theory which divides economies into three sectors of activity, extraction of raw materials, manufacturing, and services. It was developed by Allan Fisher, Colin Clark and Jean Fourastié, according to the theory, the main focus of an economys activity shifts from the primary, through the secondary and finally to the tertiary sector. Countries with a low per capita income are in a state of development. Countries in an advanced state of development, with a medium national income. In highly developed countries with an income, the tertiary sector dominates the total output of the economy. The state of development corresponds to that of European countries in the early Middle Ages, workforce quotas, Primary sector, 40% Secondary sector, 40% Tertiary sector, 20% More machinery is deployed in the primary sector, which reduces the number of workers needed. As a result, the demand for production in the secondary sector increases. The transitional way or phase begins with an event which can be identified with the industrialisation, far-reaching mechanisation of manufacture, the tertiary sector begins to develop, as do the financial sector and the power of the state. It is replaced by the demands of the tertiary sector. The situation now corresponds to modern-day industrial societies and the society of the future, today the tertiary sector has grown to such an enormous size that it is sometimes further divided into an information-based quaternary sector, and even a quinary sector based on human services. Lucius und Lucius, Stuttgart 7th edition 2002 Clark, Colin Conditions of Economic Progress Fisher, Economic Record 15.1, 24-38 Rainer Geißler, Entwicklung zur Dienstleistungsgesellschaft. 269, Sozialer Wandel in Deutschland,2000, p. 19f, Jean Fourastié, Die große Hoffnung des 20. Köln-Deutz 1954 Hans Joachim Pohl, Kritik der Drei-Sektoren-Theorie, in, Mitteilungen aus der Arbeitsmarkt- und Berufsforschung. Issue 4/Year 03/1970, p. 313-325 Stefan Nährlich, Dritter Sektor, from Theorie der Bürgergesellschaft des Rundbriefes Aktive Bürgerschaft 4/2003 Uwe Staroske, Die Drei-Sektoren-Hypothese, Darstellung und kritische Würdigung aus heutiger Sicht
Industrial output in 2005
This figure illustrates the percentages of a country's economy made up by different sector. The figure illustrates that countries with higher levels of socio-economic development tend to have less of their economy made up of primary and secondary sectors and more emphasis in tertiary sectors. The less developed countries exhibit the inverse pattern.