Existential therapy is a form of psychotherapy focused on the client’s lived experience of their subjective reality. The aim is for clients to use their freedom to live authentic fulfilled lives.

Existentialist traditions maintain:

The philosophers who are especially pertinent to the development of existential psychotherapy are those whose works were directly aimed at making sense of human existence. The fields of phenomenology and existential philosophy are especially and directly responsible for the generation of existential therapy.

The starting point of existential philosophy (see Warnock 1970; Macquarrie 1972; Mace 1999; van Deurzen and Kenward 2005) works of Søren Kierkegaard and Friedrich Nietzsche. Their works conflicted with the predominant ideologies of their time and committed to the exploration of reality.

Soren Kierkegaard (1813–1855) protested vehemently against popular misunderstanding and abuse of Christian dogma and the so-called 'objectivity' of science (Kierkegaard, 1841, 1844). He thought that both were ways of avoiding the anxiety inherent in human existence. He had great contempt for the way life was lived by those around him and believed truth could only be discovered subjectively by the individual in action. He felt people lacked the courage to take a leap of faith and live with passion and commitment from the inward depth of existence. This involved a constant struggle between the finite and infinite aspects of our nature as part of the difficult task of creating a self and finding meaning. As Kierkegaard lived by his word, he was lonely and much ridiculed during his lifetime.

Friedrich Nietzsche (1844–1900) took this philosophy of life a step further. His starting point was the notion that God is dead, that is, the idea of God was outmoded and limiting (Nietzsche, 1861, 1874, 1886). Furthermore, the Enlightenment—with the newfound faith in reason and rationality—had killed or replaced God with a new Truth that was perhaps more pernicious than the one it replaced. Science and rationality were the new "God," but instead took the form of a deity that was colder and less comforting than before. Nietzsche exerted a significant impact upon the development of psychology in general, but he specifically influenced an approach which emphasized an understanding of life from a personal perspective. In exploring the various needs of the individual about the ontological conditions of being, Nietzsche asserted that all things are in a state of "ontological privation," in which they long to become more than they are. This state of deprivation has major implications for the physiological and psychological needs of the individual.

While Kierkegaard and Nietzsche drew attention to the human issues that needed to be addressed, Edmund Husserl's phenomenology (Husserl, 1960, 1962; Moran, 2000) provided the method to address them rigorously. He contended that natural sciences assume the separateness of subject and object and that this kind of dualism can only lead to error. He proposed a whole new mode of investigation and understanding of the world and our experience of it. He said that prejudice has to be put aside or 'bracketed,' for us to meet the world afresh and discover what is absolutely fundamental, and only directly available to us through intuition. If people want to grasp the essence of things, instead of explaining and analyzing them, they have to learn to describe and understand them.

Max Scheler (1874-1928) developed philosophical anthropology from a material ethic of values ("Materielle Wertethik") that opposed Immanuel Kant's ethics of duty ("Pflichtethik"). He described a hierarchical system of values that further developed phenomenological philosophy. Scheler described the human psyche as being composed of four layers analogous to the layers of organic nature. However, in his description, the human psyche is opposed by the principle of the human spirit. Scheler's philosophy forms the basis of Viktor Frankl's logotherapy and existential analysis.