Friedrich Nietzsche (1844–1900) developed his philosophy during the late 19th century. He owed the awakening of his philosophical interest to reading Arthur Schopenhauer's Die Welt als Wille und Vorstellung (The World as Will and Representation, 1819, revised 1844) and said that Schopenhauer was one of the few thinkers that he respected, dedicating to him his essay Schopenhauer als Erzieher (Schopenhauer as Educator), published in 1874 as one of his Untimely Meditations.

Since the dawn of the 20th century, the philosophy of Nietzsche has had great intellectual and political influence around the world. Nietzsche applied himself to such topics as morality, religion, epistemology, poetry, ontology, and social criticism. Because of Nietzsche's evocative style and his often outrageous claims, his philosophy generates passionate reactions running from love to disgust. Nietzsche noted in his autobiographical Ecce Homo that his philosophy developed and evolved over time, so interpreters have found it difficult to relate concepts central to one work to those central to another, for example, the thought of the eternal recurrence features heavily in Also sprach Zarathustra (Thus Spoke Zarathustra), but is almost entirely absent from his next book, Beyond Good and Evil. Added to this challenge is the fact that Nietzsche did not seem concerned to develop his thought into a system, even going so far as to disparage the attempt in Beyond Good and Evil.

Common themes in his thought can, however, be identified and discussed. His earliest work emphasized the opposition of Apollonian and Dionysian impulses in art, and the figure of Dionysus continued to play a role in his subsequent thought. Other major currents include the will to power, the claim that God is dead, the distinction between master and slave moralities, and radical perspectivism. Other concepts appear rarely, or are confined to one or two major works, yet are considered centerpieces of Nietzschean philosophy, such as the Übermensch and the thought of eternal recurrence. His later works involved a sustained attack on Christianity and Christian morality, and he seemed to be working toward what he called the transvaluation of all values (Umwertung aller Werte). While Nietzsche is often associated in the public mind with fatalism and nihilism, Nietzsche himself viewed his project as the attempt to overcome the pessimism of Arthur Schopenhauer.

Views on truth, the self and knowledge

Nietzsche believed that there was no such thing as an objective truth, because every perception and conceptualization necessarily depended on the biases, prejudices and perspective of the observer. He put in doubt several assumptions commonly taken for granted. Against the existence of a single, unitary "I", he posited the self as a collection of several, often contradictory drives and desires, "a multiplicity of subjects whose interaction and struggle is the basis of our thought and our consciousness in general"; against the principle of cause and effect, he posited as perfectly likely that the universe is a succession of unrelated events and that a later event doesn't have to be caused by a previous event even if humans perceive it that way; against the existence of a subject independent of the action it carries out, and likewise of an object independent of the action it is subjected to, he posited that any one thing can only exist insofar as it either affects something else or is affected by something else. He also agreed with Schopenhauer's denial of free will: actions are determined by the inner struggle of conflicting desires: when one desire is strong enough, it leads to its actualization into an action; however, none is able to choose what they desire or the strength of a given desire (the strength of a desire being the only thing determining whether it will be acted out), for, otherwise, the desire would be a causa sui (to choose what to desire, or how much to desire is impossible, because "choosing" means simply "desiring something more than something else"; thus if desires were caused by choices, that would lead to the illogical conclusion that desires were caused by desires).Beyond Good and Evil, §21

According to him, the fact existence is completely chaotic, irrational and unintelligible does not mean it is unreal, because reality does not have to conform to humanity's logical prejudices. He strongly criticized the belief that the present, real world is merely a prelude or an imitation of a "True World" or "better world", such as Plato's Realm of forms or the Heaven featured in many religions. He claimed that positing a fake world is a sign of décadence and a form of life-denial, a prelude to nihilism and pessimism, since it leads people to devalue their real life and see it as cruel and unfair by constantly comparing it to an idealized and nonexistent "perfect life".

Nihilism, the Dionysian and the higher types

Nietzsche set out his philosophy in opposition to nihilism, which he defined as the feeling that life is purposeless, undesirable and not worth living. He blamed the development of nihilism on the fostering of décadence and traditional religions. The latter had cultivated over the centuries the idea that the only real objective of life was obeying God and reaching Heaven: therefore, as people stopped believing in either, they felt lost and developed a wholly pessimistic outlook.

Against nihilism, he championed the Dionysian spirit, which embraced chaos, change and adversity as the path to realization, enjoyment and self-overcoming, which he contrasted with the Apollonian spirit, which instead sought clarity and rationality. Nietzsche believed both spirits had their purpose, but that modern humanity had overemphasized the Apollonian and devalued the Dionysian. An excessive reliance on reason over sentiment had made them unable to enjoy life.

He also believed that humanity's greatest purpose was to allow for the development of exceptional, higher types (which he describes as being "sort of overmen, or Übermensch, in relation to humanity in general"),The Antichrist, §4 capable of immense power, creativity, bravery and ambition, capable of overcoming resistance, pain, suffering and even turning them to their advantage.The Will to Power, §382 This was tied to his view, as expressed in The Birth of Tragedy, that “only as an aesthetic phenomenon are existence and the world justified”. Higher men are thus necessary in order to make the world more beautiful, interesting and awe-inspiring.

He criticized Christianity, democracy and egalitarianism because he perceived them as levelling-down ideologies which aimed to drag down powerful men or hinder their affirmation, ultimately aiming to make all of humanity weak, inoffensive and mediocre: the prime cause of Nihilism was the lack of strong men, capable of eliciting reverence, keeping alive the "faith in man"The Will to Power, §3 and setting down grand goals.

Overall, he viewed lower, common people as a means to an end (the end being the higher man), dismissing the idea that they could or should dictate to a higher man what he can and can’t do. He did not advocate a lifestyle free of moral bounds for everyone, but only for the exceptional.

According to H.L. Mencken, “Nietzsche had no interest whatever in the delusion of the plain people – that is, intrinsically. It seemed to him of small moment what they believed, so long as it was safely imbecile. What he stood against was not their beliefs, but the elevation of those beliefs, by any sort of democratic process, to the dignity of a State philosophy – the pollution and crippling of the superior men by intellectual disease from below”.The Antichrist by F.W. Nietzsche translated from the German with an Introduction by H.L. Mencken; New York, 1931; edited by Alfred A Knopf

In contrast to the "dwarfing of man" promoted by modern-day society, he championed the ancient aristocracies, which put the fittest in charge and encouraged them to pursue greatness by means of what he terms the "pathos of distance": the nobles looked down upon the people over which they ruled and greatly enjoyed their feeling of superiority over them, leading to a constant desire to increase their power and strength so as to differentiate themselves even more from the commoners.

Master morality and slave morality

Aristocratic and dominant societies, such as Ancient Greece and Ancient Rome, had what Nietzsche referred to as master morality: they saw “good” as synonymous of “strong”, “powerful”, “healthy” and “beautiful”, all qualities typical of the noble ruling classes. Weak people were deemed “bad” only in the sense that they were inferior and in an undesirable state, without however any moral condemnation. The nobles granted an outlet and instinct to all their passions, including violence, which found its expression through wars of conquest, since the ruling class was also the warrior class. The aristocrats did believe they had certain obligations towards each other, but this did not constitute a universal morality, as they were allowed to treat those below or outside as they pleased.Beyond Good and Evil, §259 And even when one of the nobles broke their internal code of conduct, he was not deemed to be “evil” but simply mad (for instance, the Greeks often claimed that this sort of behavior was caused by gods breathing folly into men), and therefore, while punished as a means of mere self-preservation, was not assigned any moral blame.

There eventually arose what Nietzsche terms slave morality, which recast the powerful (those who were deemed “good” according to master morality) and all their characteristics as being “evil”, and conversely inoffensiveness as being “good”. In contrast to master morality, slave morality sees “evil” actions as something willingly chosen by people, relying on the concept of free will (which Nietzsche rejects) so as to assign its enemies moral blame, ultimately culminating in a retributive version of the afterlife, where the “good people” (the slaves) will be rewarded, while the “evil people” (the masters) will be punished.

According to Nietzsche, the slaves’ revolt in morals had begun with the Jews, a “people born from slavery”.Beyond Good and Evil, §195 Their long tribulations had led to a deep hatred towards the aristocratic societies by which they had been subjugated (such as Egypt, Assyria, Babylon and Rome). This became particularly pronounced after they had lost their own warrior class following their defeat by the Babylonian Empire, with the priests becoming the sole ruling class: since they learned to see the warrior-aristocrat as nothing but an enemy and an enslaver, they supposedly “brought into their religion hatred toward the noble, toward the exalted and proud, toward power, toward the ruling orders”. In Nietzsche's view, this conception of morality had later been inherited by Christianity, which expanded it to even greater proportions.The Will to Power, §184 Nietzsche's highly negative views of ancient Jews contrasted with his far more positive one of modern Jews.

Nietzsche believed slave morality to be founded upon the bitter, rancorous and envious resentment (ressentiment) the weak held against the strong, which he found harmful both for humanity overall (since it stumped the development of higher types) but especially for the resentful people themselves, who ended up living in a constant state of misery as a result of it.

In Ecce Homo, he suggested the only “great cure” for resentment is what he calls Russian fatalism: "that fatalism which is free from rivolt and with whom the Russian soldier, to whom the campaign proves unbearable, ultimately lies down in the snow: to accept nothing more, to take nothing more, to absorb nothing more — to cease entirely from reacting".