Lightning flashes. But is there a lightning doing the flashing? Or is it a single process? And similarly, when ‘you choose’ is there a ‘you’ ‘choosing’, or is this again one process? Nietzsche argues free will is an illusion. Lightning flashing is one process, and so are you. Free will is an invention created to make us feel guilty and deserving of punishment. Writes Alexandre Fillon.
In a famous passage from the Critique of Practical Reason , Kant aims to show how we can be sure of our free will in ordinary experience. It is not a proper demonstration, since it is impossible to prove freedom empirically, as empiricism is ruled by the determinism of the laws of nature, but rather an example that helps us to understand the relationship between morality and free will. At the same time, Kant’s strategy is to point out the limits of determinism, the position that denies the existence of free will. Let us imagine a hedonist, someone who feels incapable of resisting the inclination of his or her desires. With such a character, we might doubt the ability of their will to choose freely between one action or another. Show them a house where they can satisfy their deepest desires, but with gallows in front, and establish a clear rule: if you give in to temptation, you will be hanged. Kant ironically suggests that any hedonist will contain themselves, thanks to their own will and, above all, out of the fear of imminent death. It is thus possible, in some circumstances, to successfully fight against most of the external inclinations that seem to govern our lives. Nevertheless, a strong determinist, like Hobbes for example, would argue against Kant that this case does not prove in any way the ability of our own will to determine our actions by itself, which is the central aspect of free will. The will of the hedonist is not liberated from any external force, or even from any desire: they are merely obeying a desire more powerful than all others, the desire to stay alive, not to be killed.
Kant anticipated such an objection, which is why he proposes to confront our hedonist, or anyone else, with a much more difficult dilemma. Suppose you are forced by a prince, i.e. a powerful man, to make a false testimony against an innocent person, in order to put him to death; a case of pure injustice. You may comply because of the fear of death yourself, as in the previous case. Even stunned by fear, anyone can consider the possibility to disobey this tyrant and choose to die rather than take part in an unjust murder. According to Kant, this hesitation, preferring to obey the moral law above all else indicates that we are free beings, even if it is not followed by action. Beyond the classic debates with determinism, what is particularly interesting in this passage is the thesis that only morality manifests our true freedom as autonomy. When our will is realising the moral law, we can overcome the most powerful external determinations. Ultimately, the freest action is at the same time always a moral action. Morality reveals freedom (it is the ratio cognoscendi of freedom, says Kant), but freedom remains the fundamental principle, the keystone of morality (its ratio essendi).
Nietzsche's analysis of free will is probably less known than Kant’s moral philosophy or the great debates with determinism. It is however of great interest and interrogates this relationship between morality and free will from an unexpected point of view. For Nietzsche, as for Spinoza, free will is a delusion that has no basis in reality. He argues in a section of Twilight of the Idols  that free will might be one of the four great errors of human reason. We can first notice that he does not use deterministic arguments against this error, which reveals the originality of his view. Great philosophies do not simply criticise errors with strong arguments. They also explain the reasons for such errors and identify where they come from, in order to truly liberate the human mind from them. If we follow Nietzsche's various texts devoted to this genealogy of free will, two main sources can be identified.
Nietzsche's genealogical interpretation thus claims that free will was invented “in order to be guilty”, in order to punish and torment individuals through their bad conscience.
Morality is the first of these sources. Nietzsche often points out that free will is not just an error, but rather an invention intended to have particular effects. Who then invented such an illusion, and why?
“The doctrine of the will was fabricated essentially for the purpose of punishment, i.e. of wanting to find guilty (either “to find guilt” or “to find the guilty). The old psychology as a whole, the psychology of the will, presupposes the fact that its originators, the priests at the head of ancient communities, wanted to give themselves the right to impose punishments — or give God the right to do so ... People were thought of as “free” so that they could be judged and punished — so that they could become guilty* consequently every action had to be thought of as willed, the origin of every action as located in consciousness” .
According to this text and others, Nietzsche considers that free will is an invention that comes essentially from the morality of Christianity, through the psychology of priests or theologians, a morality that has also dominated the history of philosophy. Philosophical theories of free will were therefore a major instrument for the propagation of Christian values. As we know, Nietzsche is highly critical of this morality, which he characterises as an ascetic ideal, in other words a system of values that reject and devaluate the body, its affects and desires, and more generally the conditions of life itself. If we believe in the idea of a will of the subject that is capable of being the cause of all our actions, if we consider free will to be the fundamental principle of human behaviour, then the subject is responsible for his actions, not only for justice, of course, but above all for the moral principles regarded as universal, whether these principles take a religious form, such as God’s justice, or a purely rational form, such as Kant’s moral law. The moral concepts of duty and responsibility require free will to produce their normative authority. Nietzsche's genealogical interpretation thus claims that free will was invented “in order to be guilty”, in order to punish and torment individuals through their bad conscience.
We find here the connection between moral duty and freedom that Kant established, but from a completely different perspective. For Kant, freedom is a necessary principle for morality: without it, the universal validity of the moral law would become void, and the normative function of duty would disappear. But Nietzsche adds a critical evaluation, properly “beyond good and evil”: the essential function of moral laws is to punish human behaviour, by increasing guilt and bad conscience towards mankind. We can easily imagine Nietzsche delighting in Kant's previous text, if he was to comment about it in detail... ‘So, in order to prove free will, it seems that we have to use punishment against the satisfaction of desires, the threat of the gallows, the choice between death and eternal remorse!’
Using the fiction of free will is the best way to develop the sense of moral fault or sin, which, according to Nietzsche, is the most powerful and sophisticated torture ever invented. To feel the inner pain of guilt, I must recognise myself as a being with free will. My will is free, so I could have avoided doing this action and I will be punished by means of my guilt, by a perpetual self-punishment that will torment me more deeply than any judicial sentence. In other words, Nietzsche is attempting to highlight a form of cruelty hidden in the morality of responsibility and the concept of free will, which could be seen as morally neutral. This is why this text from Twilight of the Idols concludes abruptly: “Christianity is a metaphysics of the hangman...” 
But Nietzsche's genealogical investigation of free will does not end with this moral evaluation. There is an even more underground source explaining the possibility of this error. On what foundation could such an invention have come to be believed? On what belief could priests, theologians and philosophers have spread the idea of free will? On the grounds of language, as he already noticed in Human, All Too Human: “A philosophical mythology lies concealed in language, which breaks forth again at every moment, however careful we may otherwise be. The belief in freedom of the will, that is, in the same facts and in isolated facts — has its perpetual evangelist and advocate in language” . What is the meaning of this unusual and complex thesis, which we repeatedly find in most of Nietzsche's books?
By saying “lightning flashes”, and by thinking in accordance with these words that there is a subject “lightning” which is the cause of the act of flashing, we believe that there are two distinct things, lightning and the fact of flashing, although it is only a single process.
This idea can be analysed more clearly in two arguments. The first argument is as follows: the premise of free will is to conceive will as a psychological causality, to admit that there is within us a certain ability that can produce effects by itself. By extending the notion of causality to will, we introduce into the psychological analysis of individuals the distinction between cause and effect, which leads to a distinction between the act of willing and the set of accomplished acts. If we understand will as a cause that produces effects, then we must suppose a causal agent behind our actions, a subject that remains separated from its actions. For Nietzsche, free will is finally a concept that comes from a primary category, the category of subject, which is the substratum and the cause of actions.
The second argument explains the relationship between the category of subject and language. Nietzsche repeatedly gives the same linguistic example, “lightning flashes” (der Blitz leuchtet):
“For instance, just as ordinary people separate lightning from its flashing and take the latter as its doing, as the effect of a subject that is called lightning, so too popular morality separates strength from the expressions of strength, as if behind the strong one there were an indifferent substratum free to express strength or not to. But there is no such substratum; there is no “being” behind the doing, effecting, becoming; the “doer” is merely tacked on as a fiction to the doing — the doing is everything. The people basically double the doing when they have the lightning flashing; this is a doing-doing: it posits the same occurrence once as cause and then once more as its effect...” 
By saying “lightning flashes”, and by thinking in accordance with these words that there is a subject “lightning” which is the cause of the act of flashing, we believe that there are two distinct things, lightning and the fact of flashing, although it is only a single process. We are then doubling and falsifying reality, for such a distinction leads to the absurd belief that lightning is free to cause the act of flashing in the sky or not. This example indicates the source of the category of subject: it comes from a belief in language, and more precisely a belief in the grammatical structure of predication. The philosophical distinction between agent and act is merely the projection on reality of the subject-verb distinction in particular languages. The predicative expression in Indo-European languages, which is organised around the subject function, makes us believe that the distinction between a subject (e.g. lightning) and its predicates (e.g. flashing) has a basis in reality.
Behind lightning during a storm, some interpret the action of a free agent, such as the fury of Zeus or Thor. More generally, words and grammar we manipulate every day have such an impact on our minds and our lives that we can't help but unconsciously project their structures and meanings on to reality. This deceptive seduction of language rules our ordinary use, but also that of philosophers, who wrongly think that they have emancipated themselves from it through their concepts. Instead, they are perhaps the greatest fools of language’s spell.
Despite this strong criticism of free will, Nietzsche also refuses to defend pure determinism. Determinism, he says, often expresses a weakness of will, an inclination to reject responsibility for everything and to blame the whole world. His anti-dogmatic philosophy calls for a progressive emancipation of will. He develops in his works a very sophisticated understanding of the willing process, which is essentially understood as a complex process of ordering and obeying, in our relationships with others, but above all within ourselves. As a philosopher of the free spirit, Nietzsche seeks to liberate our mind from their prejudice, so that we become aware of the hidden beliefs at the core of knowledge, and we constantly question our supposed certitudes about what is good and what is evil. Concerning the dogma of free will, he invites us to ask ourselves if this idea is not secretly related to some moral values that need to be evaluated, although it appears to be axiologically neutral. He also invites us to liberate ourselves from our unsuspected belief in language, not in order to get rid of language – we cannot escape from it, language is the condition of human thought – but in order to employ words with more intelligence, more freedom and more creativity.
 Critique of Practical Reason, chapter 1, § 6.
 Twilight of the Idols, section VI, § 7, Duncan Large (ed.), Oxford University Press, 2008.
 Human, All Too Human II: The Wanderer and His Shadow, Gary Handwerk (trans.), Stanford University Press, 2013, § 11, p. 157.
 Beyond Good and Evil / On the Genealogy of Morality, Adrian del Caro (trans.), Stanford University Press, 2014, “First treatise: Good and Bad, Good and Evil”, § 13, p. 236.