It’s pointless to try to categorize Nietzsche’s ideas into standard philosophical categories like idealism or materialism, rationality or irrationalism. He is sometimes lumped in with the group of philosophers known as “existentialists.” This is an arbitrary and, in some ways, inaccurate category that has fallen out of favour as a result of a deeper understanding of Nietzsche’s thinking. The concept that the universe is one of becoming, not of being, and, as a result, a hostility to any philosophy that asserts a reality above and beyond the world of appearance are the only identifiable philosophical ideas for which Nietzsche frequently expresses support. The rejection of conventional religion, not just as a metaphysical doctrine but also in its consequences for moral conceptions, is an essential conclusion. These points are inextricably related to Nietzsche’s stated respect for Heraclitus:
The affirmation of passing away and destroying, which is the decisive feature of a Dionysian philosophy; saying Yes in opposition and war; becoming, along with a radical repudiation of the very concept of being—all this is clearly more
closely related to me than anything else thought to date. The doctrine of the ‘eternal recurrence’ that is, of the unconditional and infinitely related circular course of all things—this doctrine of Zarathustra might in the end have been taught already by Heraclitus.
(‘The Birth of Tragedy,’ by Ecce Homo, 3)
Nietzsche aspires to be a positive thinker, or a “yes-sayer.” However, such affirmation is contingent on transcending a system of conceptions that has dominated human thought. As a result, he is a critical thinker in practice—indeed, one of the most destructive thinkers in philosophy history. Nietzsche criticises knowledge, as well as its notions of truth and objectivity; morality, as well as its concepts of good and evil; philosophy, as well as its concepts of being or reality; and religion, as well as its concept of God. Nietzsche promotes the notions that these systems reject in each case: he maintains the importance of lying, fate, semblance, and becoming. His criticisms, however, are internal; he contends that the highest values devalue themselves. For example, we owe our desire for truth to the Christian tradition, which saw the world of appearances as one of deceit and so set the job of discovering true truth. However, the resolve to see a train of thought through to its conclusion—a capability learned with considerable struggle rather than an inherent human trait—has led to the demise of such ideas. We now understand that our knowledge is founded on metaphors, and that a metaphor is a deception since it implies the identity of something that is not identical. Human beings require these falsehoods in order to create a world of steady and regular objects in which they may exist.
Nietzsche supports this concept of knowing in his early sketches by employing a rhetorical vocabulary rather than logic. Some neo-Kantians claim that unconscious inference is the essential process of mind. Rather, figures of speech serve as a paradigm for all thinking; metonymy and metaphor are two of its most important activities. Nietzsche claims that language is made up completely of metaphors, and that metaphor, which compares the unequal, is a deception or a riddle.
What, then, is truth? A mobile army of metaphors, metonyms, and anthropomorphism—in short, a sum of human relations, which have been
enhanced, transposed, and embellished poetically and rhetorically, and which after long use seem firm, canonical, and obligatory to a people: truths are illusions about which one has forgotten that this is what they are; metaphors which are worn out and without sensuous power; coins which have lost their
pictures and now matter only as metal, no longer as coins. (‘An extra-moral sense of truth and lie’)
These concepts of knowledge correspond to the Heraclitans concept of ultimate becoming which, as Nietzsche explains, is a process without beginning or end and without halt. ‘If there was just one time to be in the literal sense,’ he says, ‘it could not be any farther.’ However, that’s not how we usually interpret the world. Our sensory organs are tailored to the survival conditions and allow us to understand just a small portion of what happens. We therefore believe that there are discontinuities and distinct things: the most passing process, like a lightning flash, is seen as something’s activity. Our language contains philosophical assumptions: ‘Every word is a prejudice’ (The Wanderer and His Shadow, section 55). Because the Indo-European languages distinguish subject from action, they govern our conceptual tendency towards faith in everlasting or at least lasting entities and eventually lead to faith in the soul and the substance. The line of thinking here is similar to the more recent ideas regarding the deciding effect of the language structure on our views of the world. But our living situations need such illusions; for it becomes absolutely impossible for the world to understand. We thus construct fiction, which allows us to understand the universe, such as objects, and consequently numbers and formulas. Nietzsche proposes no change to a new language: even Zarathustra, who declares a “new speech,” nevertheless speaks English. It appears that we should continue to use the only language that we have, while recognizing that its notions are inadequate for reality.