Most researchers believe[weasel words] that Friedrich Nietzsche (1844–1900) knew little of the 19th century philosopher Søren Kierkegaard (1813–1855). Georg Brandes, a Danish philosopher, wrote to Nietzsche in 1888 asking him to study the works of Kierkegaard, to which Nietzsche replied that he would. Nietzsche seems to have been unable to undertake this task before his mental collapse in 1889.
Recent research, however, suggests that Nietzsche was exposed to the works of Kierkegaard, through secondary literature. Aside from Brandes, Nietzsche owned and read a copy of Hans Lassen Martensen’s Christliche Ethik (1873) in which Martensen extensively quoted and wrote about Kierkegaard’s individualism in ethics and religion. Nietzsche also read Harald Høffding’s Psychologie in Umrissen auf Grundlage der Erfahrung (ed. 1887) which expounded and critiqued Kierkegaard’s psychology. Thomas Brobjer believes one of the works Nietzsche wrote about Kierkegaard is in Morgenröthe, which was partly written in response to Martensen's work. In one of the passages, Nietzsche wrote: Those moralists, on the other hand, who, following in the footsteps of Socrates, offer the individual a morality of self-control and temperance as a means to his own advantage, as his personal key to happiness, are the exceptions. Brobjer believes Kierkegaard is one of "those moralists".
Both Kierkegaard and Nietzsche, considered precursors to existentialism (or existentialists themselves), criticized the rational, idealistic, and systematic structures of philosophy. Both philosophers wrote in a fairly unsystematic way and with similar literary style. They attacked what they saw as the detrimental effect of Christendom on the population. Kierkegaard and Nietzsche condemned Christian churches for perverting Christianity, but they differ in their view of whether religion can continue to play an important part in an individual's life. Kierkegaard believed that Christian belief and faith is a much more individualistic and personal experience, filled with dread and joy, than is afforded by the comfortable social gathering of Christendom, while Nietzsche believed Christians were attached to Christianity (which Nietzsche saw as a decadent religion) in order to compensate for their individual weaknesses.
Points of comparison
Throughout the 20th century (and into the 21st century), there have been growing studies of Kierkegaardian-Nietzschean comparisons. The most prominent early scholars who studied this aspect of the two philosophers include Georg Brandes, Karl Jaspers, Jean-Paul Sartre, and Karl Löwith.
J. Kellenberger in his work Kierkegaard and Nietzsche, identified major points of comparison:
- The similarities of their lives, for example:
- Kierkegaard and Nietzsche's passion for life and philosophy
- Kierkegaard's knight of faith and Nietzsche's Übermensch
- Kierkegaard and Nietzsche's common focus on psychology (Kierkegaard's faith-based psychology - Nietzsche's power-based psychology)
- Kierkegaard and Nietzsche's common focus on religion (Kierkegaard's embrace of religion - Nietzsche's rejection of religion)
- Kierkegaard's writings on Abraham in Fear and Trembling and Nietzsche's character of Zarathustra in Thus Spoke Zarathustra
- Kierkegaard's joyfulness of faith and Nietzsche's joyful acceptance of life
- Kierkegaard's "crowd" and Nietzsche's "herd"
- Either Kierkegaard/or Nietzsche: Moral Philosophy in a New Key by Tom P. Angier (Ashgate Publishing, 2006).
- Four Prophets of our Destiny: Dostoevsky, Kierkegaard, Nietzsche and Kafka by William Hubben (Textbook, 2003).
- Kierkegaard and Nietzsche by J. Kellenberger (St. Martin's Press Inc, 1997).
- Notes and Discussions: Nietzsche's Knowledge of Kierkegaard by Thomas H. Brobjer. Journal of the History of Philosophy - Volume 41, Number 2, April 2003, pp. 251-263
- Reason and Existenz by Karl Jaspers (Marquette University Press, 1996, ISBN 0-87462-611-0).