In the Postmodern Period the strong spirit of competition a kind of "all or none" principle made only one line of thinking to be acceptable as a paradigm in scientific or other circumstances.
In the end of the 20th and the beginning of the 21th century, this model did not answer anymore all the questions or problems. It was necessary to see the possibility of different answers to one same question, and the possibility to try to understand and conciliate paradoxes.
So, it was space for a more "complex" comprehension of the world and the human being.
The notion of Complexity started in Biology, in the first half of 20th century, when some thinkers wrote about the idea that "a living being is more than the sum of its parts". So, life is more than the chemical and molecular components. Life is also a kind of net among parts of a living being and even among several living beings.
This concept of Complexity reached Philosophy and Anthropology and could be used to understand society and nature.
Thinkers like Edgar Morin and Basarab Nicolaescu wrote about Complexity. Maybe now, in the After-Postmodern Period could be possible to better understand and apply Complexity.