Nietzsche opens by questioning the will to truth that makes us such inquisitive creatures. Of all the questioning this will excites in us, we rarely question the value of truth itself.
Nietzsche confronts what he calls the "faith in opposite values." This is the belief that the world can be divided into opposites, starting with the opposition of truth and falsehood. Nietzsche suggests that perhaps the relationship between so-called "opposites" is far more complex. Often, our "truths" are born from our prejudices, from our will to deceive; they are born from our falsehoods.
For instance, conscious thinking is usually contrasted with instinct, but Nietzsche argues that most conscious thinking tends to be informed precisely by instinct. Instinctively, we value truth over falsehood, but perhaps falsehood can be a valuable--even indispensable--condition for life. While philosophers generally would like to proclaim their objectivity and disinterestedness, their instincts and prejudices are usually what inform them. At bottom, we find a bunch of old prejudices called "truths" and a whole system of philosophy built up after the fact to justify these "truths." Nietzsche believes that every philosophy is, essentially, the confession of a philosopher, and it gives us more of an insight into that philosopher's character than anything else.
To elaborate on this point, Nietzsche examines a number of different philosophers, beginning with the Stoics. These philosophers who urged us to live "according to nature" were not trying to re- create us in the image of nature (which Nietzsche argues is absurd) but were trying rather to re-create nature in the image they desired. Philosophy, "the most spiritual will to power," says Nietzsche, "always creates the world in its own image; it cannot do otherwise." This will to power, according to Nietzsche, is our cardinal instinct, more fundamental even than the instinct of self-preservation.
Nietzsche also dissects anti-realism, Kantianism, and materialistic atomism. He argues that ##Kant## never gives anything more than circular reasons for believing that there is a faculty capable of synthetic a priori judgments. Nonetheless, we need to believe in synthetic a priori judgments and will believe in such a faculty even though we don't actually have it.
Another prejudice of philosophers is the belief in "immediate certainties," the most famous of which is ##Descartes##' assertion that he cannot possibly doubt that he is thinking. This certainty only reflects a lack of reflection on what is meant by "I think." Why am I so certain that it is "I" that thinks? That I am the cause of the thinking? Doesn't a thought come to me, isn't it the thought that thinks? And how can I know, without further assumptions or certainties, that I am thinking, and not willing or feeling or something else?
Nietzsche is particularly harsh on our conception of "free will." First, he argues that the will is far more complicated than we make it out to be: the word "I" obscures and fudges together a whole complex of commanding and obeying wills. This "freedom" of the will comes only from identifying this "I" as the source both of the commanding and the obeying. The concept of free will also relies on the erroneous notions of cause and effect, which see our will as a "cause." Cause and effect are a part of a larger picture of physics, according to which nature is governed by laws. Nietzsche argues that this is a democrat's interpretation of nature: we could equally well see it as totally lawless, governed only by the unfettered assertion of wills.
Nietzsche's understanding of "truth" is subtle and deep. Logically speaking, "true" and "false" apply to sentences and propositions, not to things or wills or people. Any statement that purports to be true can be seen as expressing a particular point of view. According to Nietzsche, no point of view can comprehend absolute truth: there are only different perspectives from which one can see a matter. If one sees a matter from only one perspective, one is seeing a distorted and incomplete picture. Truth, being something expressible only in propositions, demands a point of view, a particular perspective, and, in claiming truth for that perspective, distorts the bigger picture. Truth, we might say, falsifies the overall picture. Once we abandon a belief in absolute truths and absolute falsehoods, the relationship between truth and falsity becomes richer and more complex.
Our "truths," according to Nietzsche, are not absolute, but are rather particular interpretations of what we see. For instance, Nietzsche argues that it is only "true" that nature operates according to laws if we take a particularly democratic perspective toward the workings of nature. Nietzsche sees the same regularity in nature, but doesn't interpret this regularity as the proper governance of law so much as the constancy of the domination of stronger wills over weaker ones. Nietzsche's discussion of wills will be discussed shortly.
Our interpretation of experience is ultimately based on the perspective we choose, and the perspective we choose is largely based on moral assumptions and prejudices: we see the world the way we want to see it. Philosophers are in the business of trying to justify seeing the world in their own particular way, and they come up with reasons why the world should be viewed from their perspective rather than some other. Ultimately, they see their moral prejudices and their perspective on things as "truths." As a result, philosophy is as much autobiography as anything else: philosophers attempt to justify and to convince others of what it is that drives and motivates them.
The obvious, and sometimes justified, objection to lots of talk about relative truths and perspectives and the like is: "But aren't there some things that are simply true or simply false? That 1 + 1 = 2 doesn't depend on my perspective." True enough. To understand what Nietzsche means, we need to understand his conception of the will to power.
According to Nietzsche, the significant fact about the universe is that it is always changing. A philosophy of facts and things only reinforces the misconception that the universe is fixed. Nietzsche identifies will as the agent of all change in the universe, and so focuses his philosophy more on the will. All wills struggle for domination, independence, and power over one another, which is the source of change in the universe. This change is thus effected by what Nietzsche calls the "will to power," the struggle for independence and dominance over other wills. Nietzsche sees people not as "things" or "selves" but as a complex of wills, all struggling with one another for domination. He calls philosophy the "most spiritual will to power" because it is an attempt on the part of the philosopher to impose his prejudices and assumptions--his "spirit"--on everyone else. The philosopher wants his will to be "truth."
To return to the earlier objection, 1 + 1 = 2 without a doubt, but this truth is a simple fact, and we only get a part of the picture unless we ask who asserts it and why. Why would a mathematician devote his entire life to the pursuit of such truths? What does that say about the mathematician? What does it then say about the truths? What wills are at play, what will is dominant in the pursuit of mathematics? These are the questions that interest Nietzsche, as a philosopher of the will, and not of facts and things. The "truths" of philosophers are expressions of their wills and not simple facts. A particular perspective taken on the truth is evidence for a particular will claiming dominance.
One of Nietzsche's pet peeves is the influence that grammar, and particularly the subject-predicate form, has upon philosophy. For instance, Nietzsche accuses us of misunderstanding "I think" as implying that there is an "I" which is a distinct entity, and thinking, which is an action undertaken by the "I." First of all, as Nietzsche explains, this "I" only appears as a stable thing on the surface, but it is in essence a complex of competing wills. Further, he suggests, thoughts come to us: we don't create them. While it is impossible to find a satisfactory expression in language, we might be better off substituting for "I think" the less simple sentence: "the will to think became dominant over other wills at such-and-such place and time."