The philosophy of Søren Kierkegaard has been a major influence in the development of 20th-century philosophy, especially existentialism and postmodernism. Søren Kierkegaard was a 19th-century Danish philosopher who has been labeled by many as the "Father of Existentialism", although there are some in the field who express doubt in labeling him an existentialist to begin with. His philosophy also influenced the development of existential psychology.
Kierkegaard criticized aspects of the philosophical systems that were brought on by philosophers such as Georg Wilhelm Friedrich Hegel before him and the Danish Hegelians. He was also indirectly influenced by the philosophy of Immanuel Kant. He measured himself against the model of philosophy which he found in Socrates, which aims to draw one's attention not to explanatory systems, but rather to the issue of how one exists.
One of Kierkegaard's recurrent themes is the importance of subjectivity, which has to do with the way people relate themselves to (objective) truths. In Concluding Unscientific Postscript to Philosophical Fragments, he argues that "subjectivity is truth" and "truth is subjectivity." Kierkegaard conveys that most essentially, truth is not just a matter of discovering objective facts. While objective facts are important, there is a second and more crucial element of truth, which involves how one relates oneself to those matters of fact. Since how one acts is, from the ethical perspective, more important than any matter of fact, truth is to be found in subjectivity rather than objectivity.
Note on pseudonyms
Many of Kierkegaard's earlier writings from 1843 to 1846 were written pseudonymously. In the non-pseudonymous The Point of View of My Work as an Author, he explained that the pseudonymous works are written from perspectives which are not his own: while Kierkegaard himself was a religious author, the pseudonymous authors wrote from points of view that were aesthetic or speculative. One exception to this is Anti-Climacus, a pseudonymous author developed after the writing of The Point of View: Anti-Climacus is a religious author who writes from a Christian perspective so ideal that Kierkegaard did not wish it to be attributed to himself.
Because the pseudonymous authors write from perspectives which are not Kierkegaard's own, some of the philosophy mentioned in this article may not reflect Kierkegaard's own beliefs. Just as other philosophers bring up viewpoints in their essays to discuss and criticize them, Kierkegaard assigns pseudonyms to explore a particular viewpoint in-depth, which may take up a whole book or two in some instances, and Kierkegaard, or another pseudonym, critiques that position. For example, the author, Johannes Climacus is not a Christian and he argues from a non-Christian viewpoint. Anti-Climacus, as mentioned earlier, is a Christian to a high degree and he argues from a devout Christian viewpoint. Kierkegaard places his beliefs in-between these two authors.
Most of Kierkegaard's later philosophical and religious writings from 1846 to 1855 were written and authored by himself, and he assigned no pseudonyms to these works. Subsequently, these works are considered by most scholars to reflect Kierkegaard's own beliefs. Where appropriate, this article will mention the respective author, pseudonymous or not.
Themes in his philosophy
Alienation
Alienation is a term philosophers apply to a wide variety of phenomena, including any feeling of separation from, and discontent with, society; feeling that there is a moral breakdown in society; feelings of powerlessness in the face of the solidity of social institutions; the impersonal, dehumanised nature of large-scale and bureaucratic social organisations. Kierkegaard recognizes and accepts the notion of alienation, although he phrases it and understands it in his own distinctly original terms. For Kierkegaard, the present age is a reflective age—one that values objectivity and thought over action, lip-service to ideals rather than action, discussion over action, publicity and advertising over reality, and fantasy over the real world. For Kierkegaard, the meaning of values has been removed from life, by lack of finding any true and legitimate authority. Instead of falling into any claimed authority, any "literal" sacred book or any other great and lasting voice, self-aware humans must confront an existential uncertainty.