Existentialism is not a single school of thought but rather a label applied to several systems influenced by the theories of Danish philosopher SÃ¸ren Kierkegaard (1813-1855). Existentialist thinkers consider one problem: human existence in an unfathomable (unknowable) universe. However, in considering this "plight," philosophers have arrived at different conclusions.
The founder of existentialism, Kierkegaard rejected the principles put forth by traditional philosophers such as Georg Hegel (1770-1831) who contended that philosophy is a science. According to Hegel, philosophy, like science, produces concepts that can be proven through the observation of facts.