Generation is used in various meanings in biology and sociology. In a biological sense, a generation refers to the period of time between the emergence of an organism and the end of its life. In sociology, a family generation refers to the period from when a woman grows up and gives birth to her first child. On the other hand, cultural generation refers to all people who live in the same era and experience the same culture.
A family generation is the average length of time a woman gives birth to her first child. In 2007, the period of family generation in the United States was 25.2 years, and in the United Kingdom in 2004 it was 27.4 years. In the case of Korea, the period of family generation in the 2008 survey was 30 years.
The first to define the concept of a cultural generation was the 19th-century French lexicographer Emile Littre. He called the cultural generation all people who lived in the same era and experienced the same culture. The term “generation” after the 19th century was used to express certain tendencies of the same age group. A series of changes that occurred in Europe and other parts of the world after the mid-18th century showed characteristics such as modernization, industrialization, and westernization. The ideas of the Enlightenment spread the idea that progressive change was possible in which the world and the way of life were further developed. These ideas inevitably emphasized youth, and trends such as Youth Italy, Youth Germany, Sturm-und-Drang, Youth Movement in Germany, and Romanticism movement were formed. At the end of the 19th century, European intellectuals were optimistic that the young generation would have a different freedom and liberation from the previous generation. One is that, due to socio-economic changes, the knowledge of fathers is no longer useful for their children's jobs. In addition, the gradually expanded office work and new occupations such as the military and civil servants emphasized changes that were different from the previous ones, and thus the novelty of young people was highlighted as a major strength. The other is that as a series of issues such as implementation of public education, establishment of standard language, and establishment of national media emerged, regional identity and traditional society were dismantled and nationalistic tendencies expanded. People have become accustomed to finding the identity of a person from a certain country rather than the identity of being from a specific region. Auguste Comte was the first philosopher to deal with the generation as an area of full-scale philosophical research. Comte saw social change as the result of the formation of a new generation that refused to inherit the legacy of the previous generation. In addition to these, scholars such as John Stuart Mill and Wilhelm Dilty have studied generations.
Karl Mannheim left a remarkable study of generations. He tried to combine the theory of the school that classifies generations chronologically with the period of 15 to 30 years represented by Comte and the school that emphasizes personal experience of the Romantic historical school represented by Diltai and Martin Heidegger. Mannheim believed that rapid changes in the youth generation do not occur uniformly, but rather occur complexly through a gradual process of change. Because of this, he argued that a particular generation could be divided into several sub-generations rather than sharing only one characteristic.
One of the most influential scholars in the 20th century theory of generation is Jose Ortega y Gasset.
Today's generations are defined and divided in many ways by different people. Sometimes, the criteria for dividing the generations have meaning rather than the names of the divided generations.