Beyond Good and Evil, sec. 21 (tr. W. Kaufmann):
The causa sui is the best self-contradiction that has been conceived so far, it is a sort of rape and perversion of logic; but the extravagant pride of man has managed to entangle itself profoundly and frightfully with just this nonsense. The desire for "freedom of the will" in the superlative metaphysical sense, which still holds sway, unfortunately, in the minds of the half-educated; the desire to bear the entire and ultimate responsibility for one's actions oneself, and to absolve God, the world, ancestors, chance and society involves nothing less than to be precisely this causa sui and, with more than Muenchhausen's audacity, to pull oneself up into existence by the hair, out of the swamps of nothingness.
It is easy to be seduced by the beauty and energy of Nietzsche's prose into thinking that he is talking sense when he is not. The above excerpt is a case in point. Let's take a long hard logical squint at it.
Aficionados of the Great Pessimist know that the above passage is just warmed-over Schopenhauer. For the business about <i>causa sui</i>, see On the Fourfold Root of the Principle of Sufficient Reason, sec. 20; for the rejection of (libertarian) freedom, see On the Freedom of the Will; and for more of the philosophical antics of the good Baron von Muenchhausen, see World as Will and Representation, sec. 7.
The Nietzsche passage consists of two sentences. In the first, he claims that (i) the notion of a causa sui, a self-caused being, is a contradictory notion, and that (ii) human pride is at its origin.
To evaluate the first sub-claim we need to distinguish between two readings of causa sui, one positive, the other privative. On the positive reading, a causa sui causes its own existence. Although a cause need not be temporally prior to its effect, it must be logically prior to it. But then causa sui positively construed does appear to be an incoherent notion: it implies that something can be logically prior to its own existence, which is absurd. 'Existential bootstrapping' does indeed seem to be out of the question.
There is more to it than this, but for present purposes let's just assume that causa sui positively construed is a self-contradictory notion. Construed privatively, however, it is not. For then, to say that X is causa sui is just to say that X is not caused by another. Taken privatively, a causa sui is the same as a necessary being, one whose nature is to exist.
Since there is no obvious contradiction in the notion of a necessary being, Nietzsche's first subclaim in his first sentence fails. The second subclaim says that "the extravagant pride of man" is at the root of the notion of causa sui. This is not only not obvious, but appears to be plainly false. For if there is a causa sui, God in ordinary terms, then human pride is put in its place. Indeed, part of the motivation for the rejection of God on the part of atheists like Nietzsche and Sartre and Ayn Rand is the fact that their extravagant pride cannot tolerate the existence of a being vastly superior to them. So, far from the "extravagant pride of man" being the source of the notion of causa sui, it is rather the source of its rejection.
In his second sentence, Nietzsche makes the surprising claim that the desire for freedom of the will is the desire to be causa sui in the positive sense, which implies that freedom of the will is a kind of self-causation in the positive sense. It it clear that Nietzsche wants us to conclude that the concept of freedom of the will is incoherent.
But Nietzsche is wide of the mark here. Suppose I perform action A. If I possess (libertarian as opposed to compatibilist) freedom of the will, then I could have done otherwise than A. I could have done B instead, or no action at all. It is up to me, within my power, in my control , whether or not A comes into existence. But that is not to say that I cause myself to exist, or that A causes itself to exist. What is says is that I have the power to create something distinct from me, namely, A. Now this agency, this power to create actions, is not self-contradictory.
To sum up, Nietzsche makes two mistakes in the above passage. He thinks that causa sui cannot be given a self-consistent reading. It can. He also thinks that causa sui positively construed is at the root of free will. It isn't.