Although there are certain common tendencies amongst existentialist thinkers, there are major differences and disagreements among them, and not all of them even accept the validity of the term "existentialism." In German, the phrase Existenzphilosophie (philosophy of existence) is also used.
Existentialist perspectives on God
There is a split among existentialists between those who, like Kierkegaard, conceive the fundamental existentialist question as man's relationship to God, and those who accept Nietzsche's proclamation of the "death of God." Nonetheless, theological existentialism as advocated by philosophers and theologians like Paul Tillich, Gabriel Marcel, and Martin Buber shares many of the same tenets and themes that are central to atheistic existentialism. Belief in God is a personal choice made on the basis of a passion, of faith, an observation, or experience. Just as atheistic existentialists can freely choose not to believe, theistic existentialists can freely choose to believe in God and could, despite one's doubt, have faith that God exists and that God is good.
A third type of existentialism is agnostic existentialism. The agnostic existentialist makes no claim to know, or not know, if there is a "greater picture" in play; rather, he simply recognizes that the greatest truth is that which he chooses to act upon. The agnostic existentialist feels that to know the "greater picture," whether there is one or not, is impossible for human minds—or, if it is not impossible, that at least they have not found it yet. Like Christian existentialists, the agnostic believes existence is subjective. However one feels about the issue, through the agnostic existentialist's perspective, the act of finding knowledge of the existence of God often has little value because he feels it to be impossible, and/or believes it to be useless.
As mentioned above, opinions of philosophers associated with existentialism vary, sometimes greatly, over what "existentialism" is, and even if there is such a thing as "existentialism". One version, Sartrean existentialism, is elaborated below.
Some of the tenets associated with the existentialism of Jean-Paul Sartre include:
Existence precedes essence
This is a reversal of the Aristotlean premise that essence precedes existence, where man exists to fulfill some purpose. Sartrean existentialism argues that man has no predefined purpose or meaning; rather, humans define themselves in terms of who they become as their individual lives are played out in response to the challenges posed by existence in the world.
Values are subjective
Sartre accepts the premise that something in the "Facticity" (i.e., the properties of an object or person as traditionally conceived and experienced) of an individual is valuable because the individual consciousness chooses to value it. Sartre denies that there are any objective standards on which to base values. However, this should not be confused with post-modernism. Sartre clearly believed that systems of consciousness followed clear and solid rules.
Sartre believed that people lie to themselves and, underneath these lies, people negate their own being through patterns. The preceperi is similar to what today is called insight. It is necessary to get rid of bad faith.
Sartre believed that beings possess the power to look at themselves and at another or an object, which is to use one's mind to look at the person in static. This concept of "looking" and the power to look, is referred to as The Gaze. This destroys an object's subjectivity. The thing becomes an "in itself" or an object. Sartre stated that this form of consciousness was used quite often in inter-personal relationships. People place meaning onto what other people think of them rather than what they think of themselves. This process of radically re-aligning this meaning from The Gaze onto one's own being is what leads to periods of existential angst.
Being for others
Sartre believed that people who cannot embrace their freedom seek to be "looked at," that is, to be made an object of another's subjectivity. This creates a clash of freedoms whereby person A's being (or sense of identity) is controlled by what person B's thoughts about him are.
Responsibility for choices
The individual consciousness is responsible for all the choices it makes, regardless of the consequences. Condemned to be free because man's actions and choices are his and his alone, he is condemned to be responsible for his free choices.
There are several terms Sartre uses in his works. Being in-itself is an object that is not free and cannot change its essence. Being for-itself is free; it does not need to be what it is and can change into what it is not. Consciousness is usually considered being for-itself. Sartre distinguishes between positional and non-positional consciousness. Non-positional consciousness is being merely conscious of one's surroundings. Positional consciousness puts consciousness into relation of one's surroundings. This entails an explicit awareness of being conscious of one's surroundings. Sartre argues identity is constructed by this explicit awareness of consciousness.
The Søren Kierkegaard Statue in Copenhagen.Existential themes have been hinted at throughout history. Examples include Socrates and his life, Gautama Buddha's teachings, the Bible in the Book of Ecclesiastes and the Book of Job, Saint Augustine in his Confessions, Mulla Sadra's writings, and Descartes' Meditations. Individualist politics, such as those advanced by John Locke, advocated individual autonomy and self-determination rather than the state ruling over the individual. This kind of political philosophy, although not existential in nature, provided a welcoming climate for existentialism.
In 1670, Blaise Pascal's unfinished notes were published under the title of Pensées (i.e., "Thoughts"). In the work, he described many fundamental themes of existentialism. Pascal argued that without a God, life would be meaningless and miserable. People would only be able to create obstacles and overcome them in an attempt to escape boredom. These token-victories would ultimately become meaningless, since people would eventually die. This was good enough reason not to choose to become an atheist, according to Pascal.
Existentialism, in its currently recognizable 20th century form, was inspired by Søren Kierkegaard, Fyodor Dostoevsky and the German philosophers Friedrich Nietzsche, Edmund Husserl, and Martin Heidegger. It became popular in the mid-20th century through the works of the French writer-philosophers Jean-Paul Sartre and Simone de Beauvoir, whose versions of it were set out in a popular form in Sartre's 1946 Existentialism is a Humanism and Beauvoir's The Ethics of Ambiguity.
Gabriel Marcel pursued theological versions of existentialism, most notably Christian existentialism. Other theological existentialists include Paul Tillich, Rudolf Bultmann, Miguel de Unamuno, Thomas Hora and Martin Buber. Moreover, one-time Marxist Nikolai Berdyaev, developed a philosophy of Christian existentialism in his native Russia, and later in France, in the decades preceding World War II.
Georg Wilhelm Friedrich Hegel and Arthur Schopenhauer are also important influences on the development of existentialism (although not precursors), because the philosophies of Søren Kierkegaard and Friedrich Nietzsche were written in response or opposition to Hegel and Schopenhauer, respectively.
Kierkegaard and Nietzsche
The first philosophers considered fundamental to the existentialist movement are Søren Kierkegaard and Friedrich Nietzsche, though neither used the term "existentialism". Like Pascal, they were interested in people's concealment of the meaninglessness of life and the use of diversion to escape from boredom. However, what Pascal did not write about was that people can create and change their fundamental values and beliefs. Kierkegaard and Nietzsche wrote that human nature and human identity vary depending on what values and beliefs humans hold. Objective truths (for example mathematical truths) are important, but detached or observational modes of thought can never truly comprehend human experience. Great individuals invent their own values and create the very terms under which they excel. Kierkegaard's knight of faith and Nietzsche's Übermensch are examples of those who define the nature of their own existence. In contrast, Pascal did not reason that human nature and identity are constituted by the free decisions and choices of people.
Kierkegaard's and Nietzsche's works were published too early to be considered a part of the 20th century existentialist movement. They were philosophers whose works and influences are not limited to existentialism. They have been appropriated and seen as precursors to many other intellectual movements, including postmodernism, nihilism, and various strands of psychology. Thus, it is unknown whether they would have supported the existentialism of the 20th century or accepted tenets of Jean-Paul Sartre's version of it. Nevertheless, their works are precursors to many later developments in existentialist thought.
Heidegger and the German existentialists
One of the first German existentialists was Karl Jaspers. Jaspers recognized the importance of Kierkegaard and Nietzsche and attempted to build an "Existenz" philosophy around the two. Heidegger, who was influenced by Jaspers and the phenomenologist Edmund Husserl, wrote his most influential work Being and Time which postulates Dasein (pronounced dah-zIne), literally being there—a being that is constituted by its temporality, illuminates and interprets the meaning of being in time. Dasein is sometimes considered the human subject, but Heidegger denies the Cartesian dualism of subject-object/mind-body.
Although existentialists view Heidegger to be an important philosopher in the movement, he vehemently denied being an existentialist in the Sartrean sense, and responded to Sartre in A Letter about Humanism, denying his philosophy was existentialism.
Sartre, Camus and the French existentialists
Jean-Paul Sartre is perhaps the most well-known existentialist and is one of the few to have accepted being called an "existentialist". Sartre developed his version of existentialist philosophy under the influence of Husserl and Heidegger. Being and Nothingness is perhaps his most important work about existentialism. Sartre was also talented in his ability to espouse his ideas in different media, including philosophical essays, lectures, novels, plays, and the theater. No Exit and Nausea are two of his celebrated works. In the 1960s, he attempted to reconcile existentialism and Marxism in his work Critique of Dialectical Reason.
Albert Camus was a friend of Sartre, until their falling-out, and wrote several works with existential themes including The Rebel, The Stranger, The Myth of Sisyphus and Summer in Algiers. He, like many others, rejected the existentialist label, and considered his works to be absurd. In The Myth of Sisyphus, Camus uses the analogy of the Greek myth to demonstrate the futility of existence. In the myth, Sisyphus is condemned to roll a rock up a hill for eternity, but when he reaches the summit, the rock will roll back to the bottom again. Camus believes that this existence is pointless, but he feels Sisyphus ultimately finds meaning and purpose in his task, simply by continually applying himself to it, which he views as the noble quality of man.
Critic Martin Esslin in his book Theatre of the Absurd pointed out how many contemporary playwrights such as Samuel Beckett, Eugene Ionesco, Jean Genet, and Arthur Adamov wove the existential belief that man is an absurd creature loose in a universe empty of real meaning into their plays. Esslin noted that many of these playwrights demonstrated the philosophies better than Sartre and Camus did in their own plays. Though most of the playwrights subsequently labelled "Absurdist" (based on this book) denied affiliations with existentialism and were often staunchly anti-philosphical (for example Ionesco often claimed he identified more with 'Pataphysics or with Surrealism than with existentialism) the playwrights of the Theatre of the Absurd are often linked to existentialism based on Esslin's observation.  Simone de Beauvoir, who was a longtime companion to Sartre, wrote about feminist and existential ethics in her works, including The Second Sex and Ethics of Ambiguity.
Franz Fanon a French-born critic of colonialism has been considered an important existentialist.
Maurice Merleau-Ponty, an often overlooked existentialist, was a companion of Sartre. His understanding of Husserl's phenomenology was far greater than that of his fellow existentialists. His work, Humanism and Terror, greatly influenced Sartre.
Michel Foucault would also be considered an existentialist through his use of history to reveal the constant alterations of created meaning, thus proving its failure to produce a cohesive form of reality.
Dostoevsky, Kafka, and the literary existentialists
Many writers who are not usually considered philosophers have also had a major influence on existentialism. Among them, Czech author Franz Kafka and Russian author Fyodor Dostoevsky are most prominent. Franz Kafka created often surreal and alienated characters who struggle with hopelessness and absurdity, notably in his most famous novella, The Metamorphosis, or in his master novel, The Trial. The Russian Fyodor Dostoevsky's Notes from Underground details the story of a man who is unable to fit into society and unhappy with the identities he creates for himself. Many of Dostoyevsky's novels, such as Crime and Punishment, have covered issues pertinent to existential philosophy while simultaneously refuting the validity of the claims of existentialism (notably the "superman" theory advocated by Nietzsche.) Throughout Crime and Punishment we see the protagonist, Raskolnikov, and his character develop away from existential ideas and beliefs in favor of more traditionally Christian ones, which Dostoevsky had come to advocate at this time.
In the 20th century, existentialism experienced a resurgence in popular art forms. In fiction, Hermann Hesse's 1928 novel Steppenwolf, based on an idea in Kierkegaard's Either/Or (1843), sold well in the West. Jack Kerouac and the Beat poets adopted existentialist themes. In addition, "arthouse" films began quoting and alluding to existentialist thought and thinkers.
Existentialist novelists were generally seen as a mid-1950s phenomenon that continued until the mid- to late 1970s. Most of the major writers were either French or from French African colonies. Small circles of other Europeans were seen as literary existential precursors by the existentialists themselves, however, literary history increasingly has questioned the accuracy of this idealism for earlier models.
There is overlap between the expatriate American beat generation writers who found Paris their spiritual home, and writers of road novels. This also extends to the delayed action of the French permanent enamorment with the United States' hard boiled fiction genre, which, as Truffaut and others in the Cahiers du Cinéma indicated, influenced novels and plays. To some extent as well, the surrealist movement of Andre Breton and others, which questioned the established reality, made possible the isolation of non-academic novels protagonised by amoral anti-heroes.
Existentialism since 1970
Although postmodernist thought became the focus of many intellectuals in the 1970s and thereafter, much postmodern writing considers themes similar to existentialism. Since 1970, much cultural activity in art, cinema, and literature contains postmodern and existential elements, which, ironically, would support the postmodern thesis of "borderlessness between concepts". One should not, however, confuse postmodernism with existentialism.
Books such as Do Androids Dream of Electric Sheep (1968), (now republished as Blade Runner) by Philip K. Dick, Toilet the Novel by Michael Szymczyk and Fight Club by Chuck Palahniuk both distort the line between reality and appearance while simultaneously espousing strong existential themes. Ideas from such thinkers as Foucault, Kafka, Nietzsche, Herbert Marcuse, Gilles Deleuze and Eduard von Hartmann permeate the works of writers such as Chuck Palahniuk, Michael Szymczyk and Charles Bukowski, and one often finds in such works a delicate balance between distastefulness and beauty.
Neo-Existentialism and Post-Postmodernism
Some argue, however, that this class of writing belongs to a genre of literature called Post-Postmodernism, similar to a Russian movement in the 1990s called "Excrement Literature". Contemporary American writers, such as Chuck Palahniuk and the underground writer Szymczyk have been described as belonging to this movement in literature. In their works, there are often elements of distortion from the "traditional" mode of narrative, which often try to grab and shock the reader and return him or her to their present. This function that comes through the form of their writing has been described as a "Metaphysics of Presence", in which, it is hoped, the intentionality of consciousness will be diverted from its inauthentic state of "care" (Heidegger's expression for the content, which consciousness fills itself with, often concerned with the trivialities of everyday life or "everydayness") towards such existential realizations of death, the here-and-now, freedom and all of its corresponding angst. It is in that relation, that such thinkers as Heidegger would argue, that one finds one's authenticity.
Thus, the element of literature that permeates such books as Fight Club and Toilet: The Novel is often described as existential in nature. On the other hand, such works also show a Post-modern concern, especially Fight Club, in which the main character Tyler Durden appears as a representation of the philosophy of the Post-Modern classic Anti-Oedipus, and its idealization of the schizo-subject, who resists the capitalistic order of the day, devours and spits out the social codes, and "...breaks through the walls of reterritorialization into the realm of flows, intensities, and becoming, thereby threatening the whole capitalistic system in which personal disintegration occurs, allowing revolutionary action to be possible...".
In Toilet: The Novel, the entire narrative becomes schizoid in nature, each part separated from its whole, with even the protagonists trembling with despair from their own separation, their own lack of connection to the whole, and which ends in, what Deleuze calls for in Anti-Oedipus, "a breakthrough without a total breakdown, in which the schizoid subject is distinguished from the dysfunctional schizophrenic and a certain harmony is achieved between the ugly and the beautiful, and something new is seen on the horizon." Thus, this Post Postmodernist literature can often be called a synthesis between the movements of Existentialism and Post-Modernism, or as a new genre of literature, film and art, that is of an existential nature and is an evolved form of Existentialism. Neo-Existentialism, some would say, is intrinsically different from the post post-modern via its existential emphasis.
Existentialism in psychotherapy
Many of the theories of Sigmund Freud, whom Sartre refuted systematically, were influenced by Nietzsche. Some have supposed that Thanatos and Eros were closely related to Dionysian and Apollonian aspects of Nietzsche philosophy.
One of the major offshoots of Existentialism as a philosophy is Existential Psychology. Sometimes termed the Third Force Psychology, this branch of psychology was initiated by Viktor Frankl (who had studied with Freud and Jung when young). Then early in his career he was sent to a Nazi concentration camp where he survived from 1941 through 1945. In the camps he mentally re-wrote his first book whose manuscript had been confiscated at the time of his arrest. He called his theory Logotherapy and the book was Man's Search for Meaning. Speaking at a seminar in Anaheim, California in the early 1990s, Frankl stated that in the camps he would, at times, pretend to himself that he was actually in the future, remembering his experiences and noting how he was able to survive them. His years of suffering took him to the conclusion that even in the worst imaginable of circumstances, life can be assigned a worthwhile meaning. This conclusion was the heart of Frankl's psychological orientation. Logotherapy asserts that all human beings have a will to find meaning, and that serious behavioral problems develop when they cannot find it. The therapy helps patients handle the responsibility of choices and the pain of unavoidable suffering by helping them decide to give life meaning.
An early contributor to Existential Psychology was Rollo May, who was influenced by Kierkegaard.
One of the most prolific writers on techniques and theory of Existential Psychology in the USA is Irvin D. Yalom. The person who has contributed most to the development of a European version of Existential Psychotherapy is the British based Emmy van Deurzen.
With complete freedom to decide, and through being responsible for the outcome of said decisions, comes anxiety — or angst — about the choices made. Anxiety's importance in existentialism makes it a popular topic in psychotherapy. Therapists often use existential philosophy to explain the patient's anxiety. Psychotherapists using an existential approach believe that a patient can harness his anxiety and use it constructively. Instead of suppressing anxiety, patients are advised to use it as grounds for change. By embracing anxiety as inevitable, a person can use it to achieve his or her full potential in life.
Humanistic psychology also had major impetus from existential psychology and shares many of the fundamental tenets.
Terror management theory
Terror management theory is a developing area of study within the academic study of psychology. It looks at what researchers claim to be the implicit emotional reactions of people that occur when they are confronted with the psychological terror of knowing they will eventually die.
Criticisms of existentialism
Herbert Marcuse criticized existentialism, especially in Sartre's Being and Nothingness, for projecting certain features of living in a modern, oppressive society, such as anxiety and meaninglessness, onto the nature of existence itself: "In so far as Existentialism is a philosophical doctrine, it remains an idealistic doctrine: it hypothesizes specific historical conditions of human existence into ontological and metaphysical characteristics. Existentialism thus becomes part of the very ideology which it attacks, and its radicalism is illusory". Sartre had already responded to some points of the Marxist criticisms of Existentialism in his popular lecture Existentialism is a humanism, held in 1946.
Theodor Adorno, in his Jargon of Authenticity, criticized Heidegger's philosophy, with special attention to his use of language, as a mystifying ideology of advanced industrial society and its power structure.
Heidegger criticized Sartre's Existentialism, in his Letter on Humanism:
Existentialism says [that] existence precedes essence. In this statement he [Sartre] is taking existentia and essentia according to their metaphysical meaning, which from Plato’s time on has said that essentia precedes existentia. Sartre reverses this statement. But the reversal of a metaphysical statement remains a metaphysical statement. With it he stays with metaphysics in oblivion of the truth of Being.
Roger Scruton claimed, in his book From Descartes to Wittgenstein, that both Heidegger's concept of inauthenticity and Sartre's concept of bad faith were inconsistent; both deny any universal moral creed, yet speak of these concepts as if everyone is bound to abide by them. In chapter 18, he writes,"In what sense Sartre is able to 'recommend' the authenticity which consists in the purely self-made morality is unclear. He does recommend it, but, by his own argument, his recommendation can have no objective force." Familiar with this sort of argument, Sartre claimed that bad and good faith do not represent moral ideas, rather, they are ways of being.
Logical positivists, such as Carnap and Ayer, claim that existentialists frequently become confused over the verb "to be" in their analyses of "being". The verb is prefixed to a predicate and to use the word without any predicate is meaningless. Another source of confusion in the existentialist metaphysical literature is that they try to understand the meaning of the word "nothing" (the negation of existence) by assuming that it must refer to something. Borrowing Kant's argument against the ontological argument for the existence of God, the logical positivists argue that existence is not a property.
List of major thinkers and authors associated with Existentialism
Woody Allen, Michelangelo Antonioni, Ingmar Bergman, Robert Bresson, David Cronenberg, Jean-Luc Godard, Michel Gondry, Werner Herzog, Jim Jarmusch, Richard Linklater, Alain Robbe-Grillet, Harold Ramis, Éric Rohmer, David O. Russell, Andrei Tarkovsky, François Truffaut, Tom Tykwer, Luchino Visconti, Joss Whedon
Novelists, poets and playwrights
Edward Albee, Paul Auster, John Barth, Georges Bataille, Samuel Beckett, Simone de Beauvoir, Michel Butor, Albert Camus, Louis-Ferdinand Celine, Noah Cicero, Joseph Conrad, Eugene Cullen, Philip K. Dick, Fyodor Dostoevsky, Marguerite Duras,Ralph Ellison, John Fowles, Jean Genet, André Gide, Anthony Farway, Knut Hamsun, Joseph Heller, Hermann Hesse, Henrik Ibsen, Eugène Ionesco, Franz Kafka, Jack Kerouac, Imre Kertész, Jerzy Kosinski, Malcolm Lowry, André Malraux
Herman Melville, Naguib Mahfouz, George Oppen, Chuck Palahniuk, Walker Percy, Harold Pinter, Rainer Maria Rilke, Alain Robbe-Grillet, Catherine Robbe-Grillet, José Saramago, Nathalie Sarraute, Claude Simon, Jean-Paul Sartre, Marquis de Sade, Ali Shariati, Tom Stoppard, Alexander Trocchi, Richard O. Russell, Miguel de Unamuno, Peter Weiss, O V Vijayan, Kurt Vonnegut, Richard Wright, Fritz Zorn
Simone de Beauvoir, Nikolai Berdyaev, Henri Bergson, Emil Cioran, William A. Earle, José Ortega y Gasset, Martin Heidegger, Karl Jaspers, Hans Jonas, Søren Kierkegaard, Walter Kaufmann, Ladislav Klíma, Emmanuel Levinas, Gabriel Marcel, Friedrich Nietzsche, Jean-Paul Sartre, Lev Shestov, Max Stirner, Miguel de Unamuno, Peter Wessel Zapffe, Colin Wilson, Paul Ricoeur, Mahmoud Khatami.
Ernest Becker, Ludwig Binswanger, Medard Boss, Frantz Fanon , Viktor Frankl, Thomas Hora, R. D. Laing, Abraham H. Maslow, Rollo May, Fritz Perls, Otto Rank, Irvin D. Yalom
Martin Buber, Rudolf Bultmann, John Macquarrie, Gabriel Marcel, Paul Tillich
In cinema, postmodern editing techniques, showing the displacement, discontinuity, and temporal perspective of post-modernism, can go hand-in-hand with a purely existential story, thus synthesizing technique and function to give meaning. Moreover, this has created the neologism "Neo-Existentialism"—combining post-modernism's epistemology with the reflective ontological belief of existentialism. Existential cinema deals with themes of:
Retaining authenticity in an apathetic, mechanical world—something postmodernism would staunchly reject, as authenticity is related to a non-existent "reality"
The consciousness of death, for example Heidegger's "being towards death", exemplified in Ingmar Bergman's film The Seventh Seal (1957)
The feelings of alienation and loneliness consequent to being unique in a world of indifferent others, or, in Kierkegaard phrase, "the crowd" or Nietzsche's "the herd"; as personified by the character of Oh Dae-su in the 2003 Korean film Oldboy
The concept Alltägliche selbstsein ("Everyday-ness," or ennui), which Heidegger explicated in his book Sein und Zeit (1927) (English translation: Being and Time)
The 1952 classic High Noon, starring Gary Cooper as a sheriff abandoned by the townspeople as he faces alone a vengeful killer, has often been described as an "existential Western".
A major existential movement in cinema was launched by the advent of French New Wave cinema in the 1960's. Landmark films during this period were Breathless, directed by Jean-Luc Godard and written by Francois Truffaut. Truffaut released his masterpiece, The 400 Blows, in the same year. Both Godard and Truffaut would go on to become flagbearers of existentialist cinema and produce notable films like Alphaville, Bande a part, Stolen Kisses and Bed and Board.
The acclaimed 1976 film Taxi Driver, starring Robert DeNiro, is perhaps one of the most widely known existential films. The film was heavily influenced by Dosteovsky's Notes from Underground and even quotes Dosteovsky in the line: "I'm God's lonely man." The 2004 film The Machinist is also influenced by Dosteovsky's work, especially The Double: A Petersburg Poem, The Idiot, and The Brothers Karamazov. In one scene in the film, star Christian Bale is seen reading a copy of The Idiot. Another film released in the same year, I ? Huckabees revolves around two existential detectives, who aim to help people solve their personal existential crises.
The introduction sequence of the 1957 film Love in the Afternoon contains the witty remark "even existentialists make love in Paris."
The 1972 film Deliverance, as well as the 1970 book of the same name, have also been credited as existentialist, as has Fight Club (1999), eXistenZ (1999) and The Matrix (1999).
The 2003 film Lost in Translation (film), directed by Sofia Coppola, contains existential themes.