"Man first of all exists, encounters himself, surges up in the world – and defines himself afterwards." That is how Jean-Paul Sartre described the central beliefs behind existentialism in his 1946 work L'existentialisme est un humanisme, considered one of the pivotal tracts on existentialism.
In greater detail, existentialism is the belief that life has no meaning, and the only way to give it meaning through the chaos is to create meaning yourself. This is often summed up in existentialist thought and writing as the idea that existence precedes essence – we must create our own meaning to our lives if we want to have any.
Due to its emphasis on chaos and disorder, existentialism is often seen as a pessimistic view of life, but this is not entirely accurate. Unlike nihilism, an often completely contrary philosophy with which existentialism is often confused, existentialism suggests that there is hope for meaning in the world if only we can create it for ourselves. This artificial meaning will always be just that, but at least it can exist.
There are several different fields within existentialism, but all share the same basic tenets. As outlined by Jean-Paul Sartre, the basic beliefs of existentialism are:
The roots of existentialist thought are usually traced back to the Danish philosopher Søren Kierkegaard, who developed many of the early 19th-century ideas regarding human existence and the so-called "meaning of life." Along with Friedrich Nietzsche, who followed shortly after him, Kierkegaard's writings provided the basis for much of the 20th-century thought in this area, though Kierkegaard and Nietzsche would likely have both found many points with which to disagree with when it came to the existentialism of later decades.
By the turn of the century, many European philosophers, writers, and artists were beginning to show the influence that existentialist thought had on them. One of the primary examples was Franz Kafka's writings, especially Die Verwandlung, or The Metamorphosis, which explored the idea of a chaotic world with no inherent meaning. Some writers also adopted their own variations of early existentialist thought, especially Fyodor Dostoevsky, who came to subscribe to the subideology of Christian existentialism.
The movement reached its peak in the 1940s with the works of thinkers like Martin Heidegger, Albert Camus, Jean-Paul Sartre, Simone de Beauvoir, Maurice Merleau-Ponty, and Jacques Lacan. Although many of the major thinkers of the period shunned the title of "existentialist," their ideas proved to be enormously influential on the philosophy, with many of their writings – including Sartre's Being and Nothingness (1943) and Camus' The Fall (1956) – becoming touchstones of intellectual work in the 20th century.
In the 1950s, as postmodernism became the preferred intellectual focus for many philosophers, existentialism lost some of its hold on the major philosophical movements and discussions of the time. However, its major ideas and principles have continued to be explored in philosophy, literature, art, music, film, and beyond since then, constantly developing in new ways. The existentialist idea of the absurd has influenced everything from military policy discussion to Monty Python films. Through the work of clinician Ludwig Binswanger, it has even influenced new approaches to psychotherapy. Traces of existentialism can be found in almost every intellectual, cultural, social, and even political discussions of the 20th and 21st centuries since its heyday.