Generetion, as a time period, is a widespread concept (or perhaps an idea) in History, in Social Sciences, and also in common language. Do historians have some sort of consensus on the time span of a generation? Why?I would appreciate if you could provide some reliable sources for your answer (more reliable than the ones I present below).
Some previous search results:
When searching for "generation" on Stack Exchange History, 695 results are returned. However, there is no single definition of the concept that I could find.
Wikipedia has a page for the "social concept" of generation. It says:
A generation is "all of the people born and living at about the same time, regarded collectively." It can also be described as, "the average period, generally considered to be about 20–30 years, during which children are born and grow up, become adults, and begin to have children." [...]
Generation is also often used synonymously with cohort in social science; under this formulation it means "people within a delineated population who experience the same significant events within a given period of time". Generations in this sense of birth cohort, also known as "social generations", are widely used in popular culture, and have been the basis for sociological analysis. Serious analysis of generations began in the nineteenth century, emerging from an increasing awareness of the possibility of permanent social change and the idea of youthful rebellion against the established social order. Some analysts believe that a generation is one of the fundamental social categories in a society, while others view its importance as being overshadowed by other factors including class, gender, race, and education, among others.
- This other question of Stack Exchange History also uses the idea of a generation spanning a period of 25 years (implicitly, in the title) or a period between 20 and 30 years (explicitly, in the body of the question).
Additional sources of information:
I did some additional research and found out some controversy with the idea that generations usually lasts between 20-30 years, with 25 years as a good average approximation, as stated (in the aforementioned links) by Wikipedia, by another Stack Exchange History question, as well as in most of the comments to my question.
- First, this article by Pew Research Center considers:
A generation typically refers to groups of people born over a 15-20 year span, such as the Millennial generation, currently the youngest adult generation.
- Second, this paper entitled Generation, life course and news media use in Sweden 1986–2011 says:
As a point of departure, the generation analyses use the widely recognized classification of the dutifuls (1926–1945), the baby boomers (1946–1964), generation X (1965–1976) and the dotnets (1977–1995).
That is, it takes four "widely recognized classification" of generations and they range between 12 years (generation X) and 20 years (dutifuls).
- This other paper named Generation Alpha: Marketing or Science? says:
According to the model made by Strauss and Howe (1991), a generation change takes place in our society around every 20 years, with some signs of cyclicality.
They are referring, in the above sentence, to this book, which I do not have access to verify the quote.
The main goal of this third additional source is to criticize, as unscientific, the approach of a social researcher, Mark McCrindle, who published a book, entitled: "The of XYZ: Understanding the Global Generations". According with Google Scholar this book has over 550 citations. I also do not have access to this book, but this site writes about it:
Australian social researcher Mark McCrindle recently coined the term Generation Alpha to describe the generation born between 2010 and 2020.
He argues that as the world advances, it makes sense to cut the generational boundary to a 15-year maximum. McCrindle also hopes this naming strategy will stick and every 15 years there will be a new generation named successively with Greek alphabet letters.
- Finally, the third paper mentioned above also makes an interesting introductory statement based on the work of the Sociologist Karl Mannheim:
According to Mannheim, an age group can be considered a generation if they share some immanent attributes, generational consciousness or communal characteristics. For this to happen, three requirements must be met: shared experiences, actual cohesion, common attitudes, and forms of behavior (Mannheim, 1969).
This last statement is also coherent with the concept of generation mentioned in Wikipedia as being used in social sciences. However, apparently, there is an unnoticed growing gap between the biological concept of generation described as, "the average period, generally considered to be about 20–30 years, during which children are born and grow up, become adults, and begin to have children" and the sociological concept of "an age group that share some immanent attributes, generational consciousness or communal characteristics".
The quote of Wikipedia on biological generation length is based on an OECD document which was "retrieved in 2011", but has a broken link. A search for the original document, leaded me to this updated publication of 2019 showing that: "In most OECD countries, the average age at which women give birth now stands at 30 or above".
That is, while biological generation time span has widened to above 30 years, the sociological generations time span apparently has shrunk to under 20 years. This probably has important consequences to social, and therefore, historical dynamics.
If this hypothesis holds, then the average social distance between parents and children (that is, individuals that are one biological generation apart) may be about two social generations. That means the distance on "actual cohesion, common attitudes, and forms of behavior" between parents and their children might be equivalent today as it was between grandparents and grandchildren in the past, potentially leading to new forms of intergenerational conflicts and social polarization.