1D’Alembert, like the other encyclopedists and Enlightenment philosophers, is far from being a champion of progress. [1] He is, as we shall argue here, a philosopher who presents himself as a skeptic similar to Hume, but who is in fact an atheist materialist. We propose to test his “reasonable” skepticism against the way in which he discusses the question of freedom in several texts. We shall study D’Alembert’s problematic of freedom in Éléments de philosophie (Elements of Philosophy), an unpublished clarification of his views on freedom, some of his letters to Frederick the Great of Prussia, and finally in three articles from the Encyclopédie.

2In chapter 7 of Éléments de philosophie, D’Alembert reduces the idea of freedom to an entirely negative concept, that of “a power that is not exercised, and whose very essence is to not be exercised at the moment when we feel it; this idea is therefore only an operation of the mind, by which we distinguish the power to act from the action itself, and consider that this idle (but real) power remains even when the action is over.” [2]

3Later in chapter 7, he tells us that we should pay attention to the inner feeling that convinces us that we are free, and trust in the power of this feeling. He therefore offers a proof of the existence of freedom analogous to his proof of the existence of bodies: “In short, the only possible proof of this truth is analogous to that of the existence of bodies; genuinely free beings would not have any more powerful feeling of their freedom than the feeling that we have of our own freedom; we must therefore believe that we are free.” [3]

4Let us briefly recall D’Alembert’s argument with regard to the existence of external bodies:

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The only reasonable answer to the Skeptics’ objections to the existence of bodies is this: identical effects arise from identical causes; however, if we posit the existence of bodies, the sensations they would make us feel could not be any more powerful, nor more constant, nor more consistent than the sensations that we actually feel; therefore, we must assume that bodies exist. This is how far reasoning can take us in this matter, and no further. [4]

6His reasoning consists in taking account of the effect: the power, constancy, and consistency of sensations. If we imagine external bodies as being the origin of sensations, we would observe the same effect: the sensations would have the same power, the same constancy, and the same consistency as they do in reality, therefore we can consider ourselves to be justified in our actual tendency to attribute sensations to external bodies. In other words, since the existence of external bodies is an incontrovertible fact, we only need prove that they are capable of causing our sensations to prove that they actually are causing them, which amounts to heeding our actual tendency to attribute our sensations to the virtual or real causes that give rise to them, and choosing the real causes. [5]

7D’Alembert makes the same argument with regard to freedom, observing that the feeling of freedom is powerful, constant, and consistent, and this is sufficient in itself. We must take heed of this effect, whether it is attached to a real or supposed cause, that is, whether we are actually free beings, or only believe ourselves to be free. If genuinely free beings existed, the feeling of freedom would be the same. In other words, if we posit free beings as the origin of this feeling, we would observe the same effect, therefore we can consider the actual feeling of freedom to be justified. This reasoning involves always heeding the actual feeling of freedom that makes us attribute our actions to either virtual or real causes of freedom, and choosing the real causes.

8However, unlike in his reasoning about external bodies, D’Alembert does not add that since the existence of free beings is an incontrovertible fact, we need only prove that they are capable of being the cause of the feeling of freedom to prove that they actually are. And with good reason: in the clarification on freedom, which long remained unpublished and had been intended to supplement chapter 7 of Éléments de philosophie (as shown by a note on the manuscript at the Bibliothèque de l’Institut de France), D’Alembert condemns the illusion of the feeling of freedom. [6] The power to act, separated from the action itself, is no more than the awareness of the motives that drive us to act, but the motives of which we can be aware by no means constitute all the causes of our action, for the influence on our action of which we are unaware is “all the more powerful when we do not feel the effect of it,” as D’Alembert tells us in the clarification on freedom. In other words, we believe ourselves to be free because we are unaware of the causes that determine our action. And the feeling of freedom is merely an illusion. D’Alembert’s position is Spinozian, even though, like many philosophers of his time, he had probably not read Spinoza. We shall return to this point. He had, however, read Hume and Locke, and these two other references are crucial here for understanding the development of his conception of freedom.

9Indeed, the idea of separating the power to act from the action itself is already present in Hume’s discussion of freedom. Hume demonstrates that the idea of power [7] on which it is built is no more than a pure fiction of the imagination. [8] By an argument [9] close to D’Alembert’s, which we have just set out, Hume recognizes freedom only in a conditional form: “By liberty, then, we can only mean a power of acting or not acting, according to the determinations of the will; that is, if we choose to remain at rest, we may; if we choose to move, we also may. Now this hypothetical liberty is universally allowed to belong to everyone, who is not a prisoner and in chains.” [10]

10D’Alembert therefore draws on Hume in presenting the feeling of freedom as an illusion. In fact, their conceptions of freedom share a common origin, namely in the thought of Locke, although they do not follow his in every way. [11] Locke associates the concepts of freedom and spontaneity. But by attributing a productive capacity to freedom, and making it into an active power, Locke imagines the mind as being the foundation of this active power. [12] It is even through the mind’s reflection on its operations, and the experience that it has of itself, that it acquires the idea of an active power. Locke proposes to demonstrate this point throughout chapter 21: “only I thought it worth while to consider here, by the way, whether the mind doth not receive its idea of active power clearer from reflection on its own operations, than it doth from any external sensation.” [13] The mind is therefore given a priori as a necessary condition for grasping the idea of an active power, and for its execution: “it is the mind that operates, and exerts these powers [freedom, will, understanding]; it is the man that does the action […]. For powers are relations, not agents.” [14] This conception of the mind as being a priori a foundation for active powers is completely alien to Hume’s thought, which conceives of the association of freedom and the freedom of spontaneity, not in the form of an intrinsic relation between an active power and an always already present mind, but in the form of an extrinsic link between cause and effect. This Humean conception of freedom amounts to refuting that freedom possesses any productive capacity. There is never more than a constant conjunction between motives and actions. We never experience subjectivity as such. Of course, in this matter Hume differs from Locke, and goes further than D’Alembert in his critique of freedom. This is due to the fact that in the Enquiry Concerning Human Understanding he directly attaches the question of freedom to his critique of causality. [15] As D’Alembert has not elaborated any such criticism, he maintains his claim about the negative nature of ideas of freedom and the power to act. In chapter 7 of Éléments de philosophie (which presents a less extreme version of his critique of freedom, as we have seen) he tells us that we must heed the inner feeling that convinces us of our freedom, and trust in the power of this feeling.

11This reasoning is, at best, an argument of plausibility and not a proof of the existence of freedom. The argument of plausibility disguises the difficulty of the question and therefore avoids it. “Reasonable skepticism” protects the principles of reason and of causality from the destructive, or at least disturbing, effects of a genuinely critical thought such as Hume’s, since, for D’Alembert, “to wish to proceed in this matter beyond the evidence of internal feeling is to cast oneself head first into darkness.” [16]

12This reasonable skepticism is confirmed by the publication history of D’Alembert’s various texts on freedom. Éléments de philosophie was published in 1759 in volume 4 of Mélanges de littérature, d’histoire et de philosophie (Collections of Literature, History, and Philosophy), while the unpublished clarification on freedom probably dates from 1767, since the Éclaircissements sur les Éléments de philosophie (Clarifications on the Elements of Philosophy) were published in this year in volume 5 of Mélanges. However, the Éclaircissements were written in response to questions from Frederick the Great of Prussia on certain points in Éléments de philosophie. The clarification on freedom is therefore probably also D’Alembert’s response to a question posed by the king on chapter 7 of Éléments de philosophie.

13When we compare these two texts, D’Alembert’s position is ambivalent. In Éléments de philosophie, he defends a moderate position: yes, there are reasons to believe that we are free, and he provides one such argument in the reasoning that opposes a real cause (there are free beings) to a virtual cause (we believe ourselves to be free), and decides in favor of the real cause. But in his clarification on freedom, he says what he really thinks, namely that free will is an illusion of consciousness. However, he concludes with a kind of skeptic retraction, and moreover decides not to publish this text in the Éclaircissements of 1767. [17]

14Three years later, D’Alembert once again broaches the question of freedom in the midst of a discussion with Frederick the Great about the Baron d’Holbach’s work, the Système de la nature (The System of Nature). D’Holbach’s work was the subject of a long discussion that began in the summer of 1770 and ended in April 1771. The long duration of the discussion was due to the importance of the themes that it addressed. The Examen critique du système de la nature (Critical Review of “The System of Nature”) undertaken by the king in response to d’Holbach’s work summarizes its four main points: “The principal points that he [d’Holbach] addresses in this work are: (1) God and nature; (2) fatalism; (3) morality and religion, in comparison with the morality of natural religion; (4) monarchs, the cause of all the ills that states experience.” [18]

15In the discussion of the first point, D’Alembert pushes Frederick’s Voltairean Deism [19] toward a Spinozism that is at first affirmed, [20] and then disguised:

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We are therefore reduced, with the best will in the world, to recognizing and admitting that the universe possesses only a material, limited, and independent God at the very most; I do not know if that is his view, but it is certainly not that of the zealous partisans of the existence of God; they would rather we were atheist than the Spinozists that we are. To placate them, let us call ourselves skeptics, and repeat after Montaigne, what do I know? [21]

17D’Alembert is speaking here of Spinozists and not of Spinoza himself. This attitude is entirely consistent with the spirit of the age, which uses the term “Spinozism” in the general sense of a materialism that is more or less vitalist, according to whether one is referring to the old or modern Spinozism. [22]

18When D’Alembert identifies as a Spinozist, we might ask what meaning he gives to this word. If we read the letter of November 30 in its entirety, and that of February 1, 1771, we find that D’Alembert refers to “a third-hand Spinozism,” that is, Spinoza as he is read and edited by Bayle, who is himself read and edited by Voltaire. In fact, Spinoza was not widely read, whereas Bayle’s refutation of Spinoza was very well known by all the thinkers of the eighteenth century.

19Voltaire, having presented Bayle’s reading of Spinoza to the Prince de ***, [23] offers him his own reading:

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According to him, everything is necessary, everything is eternal: creation is impossible; there is no design in the structure of the universe, the permanence of species, and the succession of individuals. Ears are no longer made for hearing, nor eyes for seeing, nor the heart for receiving and expelling blood, the stomach for digesting, the brain for thinking, the generative organs for giving life; and divine intentions are nothing but the effects of blind necessity. This is the essence of Spinoza’s system […]. Atheism can do no good to morality, and can do it a great deal of harm. It is almost as dangerous as fanaticism. [24]

21This conclusion is very similar to one that Frederick draws in his Examen critique du système de la nature, regarding the principle of fatalism:

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The principle of fatalism leads to the most harmful consequences for society […]. It views men as no more than machines, some made for vice, others for virtue, incapable of deserving or being undeserving by themselves, and therefore of being punished or rewarded; this undermines morality, good public conduct, and the foundations on which society is built. [25]

23Frederick rejects the principle of fatality, which, in his review of the second point of the Système de la nature, concerning the question of freedom, results in a recognition of the positive freedom of man, which he defines as follows: “By this word, I mean every act of our will that is determined by itself and without constraint.” [26]

24On this question, D’Alembert does not follow Frederick’s thought. He tends towards a more radical Spinozism. In the letter of August 2, 1770, he begins by demonstrating that social morality and the system of fatalism and necessity are not incompatible. In the letter of November 30, 1770, while apparently supporting Frederick’s position, he actually diverges from it decisively by adopting the argument that Spinoza makes in his letter to Schuller (letter 58), to show that belief in freedom, in the sense of free will, is an illusion of human consciousness. [27] In the letter of February 1, 1771, in contrast to Frederick, who does not accept the system of fatality and necessity in all its consequences, [28] D’Alembert no longer leaves any place at all for freedom of choice. He reduces it to being merely the effect, certainly willing but still necessary, of the series of causes that determine us in our action:

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I find myself once again, sire, perfectly in agreement with Your Majesty on the definition of freedom. I define it as Your Majesty does, that act of our will that makes us choose between different options, and that determines our choice. But I would argue, and Your Majesty would not dispute it, as it seems to me, that there are always some sort of motives and causes that necessarily determine our choice, and I do not see that Your Majesty’s observations prove the contrary; those men who resist their passions, do so owing to motives that are stronger than those passions; and when exhortations, sanctions, and rewards determine men’s actions, they do so because they have greater power over them than the contrary motives. It therefore seems to me that we always act by necessity, although willingly. I very willingly forbear from poisoning myself, but I also do so necessarily, because the reasons that attach me to my life at that moment are stronger than those that could detach me from it. [29]

26The apparent reconciliation of the two points of view disguises a real divergence in their respective conceptions of freedom. D’Alembert concludes the discussion in his letter of April 21, 1771, by an argument about the obscurity of metaphysical questions. His “reasonable skepticism” is a very convenient protection from allowing the divergences of ideas to appear too flagrantly. [30] In reality, D’Alembert is far more daring than Frederick in his approach to this question.

27Furthermore, he is not at all dismayed at the idea of man as an automaton or a machine, since he presents this idea explicitly in his article on the “Fortuit” (“The Unexpected”) in the Encyclopédie:

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Let us imagine a thousand worlds existing at once, all the same as this one, and therefore governed by the same laws; everything would happen in exactly the same way. Because of these laws, men would carry out the same actions at the same moment in each of these worlds; and an intelligence other than the Creator, looking on these identical worlds, would believe their inhabitants to be automata, even though they were not, and even though each of them would internally be convinced of the contrary. Inner feeling is therefore the only proof that we have and could have of being free. [31]

29The only guarantee that man is not a machine is the inner feeling of freedom, of which D’Alembert demonstrated the fragile and illusory nature in the unpublished clarification on freedom.

30What is more, unlike Frederick, D’Alembert does not find in this conception of the man-machine a danger for morality. Indeed, as he asserts in the article on the “Fortuit,” morality is ultimately a simple question of legislation: most men commit the same acts, out of fear of punishment and appetite for reward, as the wise man does in the name of reason:

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to say, as some philosophers do, that the laws are based on freedom, and that it would be unjust to punish crimes if they were necessary, is to establish an evident truth by a very weak proof. Even if men were pure machines, it would suffice for fear to be one of the principal drivers of these machines, for this fear to be an effective means of preventing a great number of crimes […]. The necessary effect of fear is to hold back the hand of the real or supposed automaton; to prevent or stop this mechanism would amount to preventing its effect; therefore punishments would be, even in a society of automata (which does not exist) [ah, we can breathe easily!] a necessary tool for maintaining the machine. [32]

32The position that D’Alembert defends here is not at all one of a reasonable or moderate skepticism, but rather one of an atheist materialism, like that of Helvétius, according to which men are governed by their own interest alone. Since human beings wish to be happy, it suffices to enact laws that take into account the driving force of personal interest or the fear of punishment to guarantee a peaceful society. D’Alembert adds: “The notion of good and evil is therefore a consequence of the notion of freedom, and freedom is not a consequence of the notion of moral goodness and evil.” [33] The feeling of freedom is therefore the first principle that gives rise to the notions that we have of good and evil. But if we reread the article carefully, including the thought experiment of the thousand worlds in which men automatically commit the same acts, we observe that the values of good and evil are irreversibly relative: there is no good in itself, nor evil in itself, since D’Alembert traces these notions back to the feeling of freedom, of which he shows, in reality, the great fragility.

33Suddenly, religion itself is put in danger, as shown by D’Alembert’s mention, not without irony, of the different solutions that philosophers have offered to the problem of the compatibility of freedom and divine Providence, as well as to the problem of the compatibility of evil and suffering on Earth with the existence of an all-powerful God:

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With regard to the way in which our freedom co-exists with eternal Providence, with the system of justice by which God punishes crime, with the immutable laws to which all beings are subjected, this is a secret that we cannot fathom, and which the Creator has not seen fit to let us understand; but it is perhaps no less incomprehensible how brazenly certain men, who believe or declare themselves to be wise men, have attempted to explain and reconcile such mysteries as these. […] In the project to reconcile (despite the Oracle of God himself) the two truths at hand, they only succeed in destroying one of them, or perhaps weakening both of them: and so there is not a single sect of scholastics who, after exhausting themselves in arguments, distinctions, niceties, and systems in relation to this important question, do not finally come, under the weight of contradictions, to declare the profundity of eternal decrees.

35We can recognize here an interesting argument that is also defended by Pascal: when we seek to rationalize the truths of faith, we actually make them more fragile, since their principles are felt by the heart, and not by reason. [34] This critique of the confusion between the domains of faith and reason has an undeniably Pascalian tone, which should not surprise us when we consider that D’Alembert was educated at the Collège Mazarin, by Jansenist teachers whom he criticizes in his article “Collège” for their useless teaching, which undermined their pupil’s faith. [35] However, D’Alembert concludes on a skeptic note at the end of the article: “The true philosopher is neither Thomist, nor Molinist, nor congruist; he recognizes and sees everywhere the sovereign power of God; he admits that man is free, and remains silent about that which he cannot understand.” [36]

36Two other articles from the Encyclopédie confirm D’Alembert’s falsely moderate position on the question of freedom.

37Although D’Alembert is not the author of the article “Cabale (Premier Principe)” (“Kabbalah (First Principle)”), he adds a final note that resonates as a subversive conclusion. Strictly speaking, this is a remark by the editor-commentator, analogous to the ones by Diderot, marked with an asterisk, which supplement or comment on an article. The abbot Jean Pestré (“C” in the Encyclopédie) is in fact the author of the long article “Cabale (Premier Principe),” where he sets out in great detail the general principles of Kabbalah, though admits that he is not sure of having presented them clearly, as the subject is so difficult: “These are the general principles of Kabbalah, which we have tried to explain clearly, although we do not flatter ourselves that we have succeeded.” [37]

38D’Alembert cannot resist the temptation to add his own final word:

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This is all so much fantasy; but the history of Philosophy, that is, of the extravagant claims of a great number of scholars, belongs to the scope of our work; and we believe that it can even be a rather curious and interesting spectacle for Philosophers, to behold the musings of their peers. We can certainly say that there is no sort of madness that has not passed through the heads of men, and even of wise men; and thank God, we have undoubtedly not yet come to an end of it. These Kabbalists who discover so many mysteries by transposing letters; this light emanating from the head of the great Anpin; the blue flame that the Brahmins seek at the end of their nose; the Tabor Light that the umbilicals think they see at their navels; all these visions are roughly in the same vein: and after reading this article and several others, we might well think of this line from Racine’s The Litigants: [38] What fools! I have never witnessed such an affair.

40The philosophers who seek to demonstrate first principles are placed in the same group as the Kabbalists who transpose letters or make light issue from their heads, or the Brahmins who seek it at the end of their nose: all of this is extravagance, musing, and madness. In this context, all we can do is watch the spectacle, not of nature, but of philosophy, in other words the spectacle of the musings of our peers. Here we find D’Alembert’s ironic detachment, which expresses a critical philosophy with regard to the metaphysical pretensions of the philosophers.

41Finally, the last article that manifests D’Alembert’s atheist materialism is the article “Futur contingent” (“Future contingent”). This article is directly connected to the problematic of freedom and necessity. D’Alembert begins by giving a conventional definition of the future contingent:

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In Philosophy we use the term future contingent to describe that which should occur, but which will not necessarily occur. For example, the proposition tomorrow I shall go to the country is a proposition of the future contingent, not only because I might change my mind between now and tomorrow, but also because I might not have made this decision, and there is no contradiction whether I go or do not go to the country on a given day. [40]

43But from the first paragraph of the commentary, he reduces the future contingent to the voice of a human delimiting his own future contingent, because he is unaware of all the causes and interactions of the universe. It is only for the human being that a particular future can be delimited, and only on the condition of considering this absolutely and in itself can it be said to be contingent:

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When we say that the non-existence of the future contingent does not involve any contradiction, we must consider the future event absolutely and in itself, and not relative to the present system of the universe, its laws of motion, the events that must prepare for and produce the action in question, and ultimately the decrees and foresight of the Creator; for, if we consider instances of the future contingent from these perspectives, we can say that they are no longer contingent, as they must inevitably come to pass. [41]

45The reference to divine foresight is equated with reference to the system of necessity, as the article “Fortuit” showed, which is mentioned a little later in this paragraph. And this is confirmed again in the following paragraph, in which D’Alembert advances a step further in setting out the perspective of the atheist:

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Atheists who admit that the world and matter are eternal and governed by necessity do not recognize any future contingent; because the world, in their view, could not be any different, and events are a necessary consequence of the collisions and motion of bodies: but in the view of all philosophers, and as reason itself dictates, there are future contingents in the sense that God, who created and arranged the world, could have arranged it differently, and the events that occur inevitably in the world, arranged such as it is, would not have occurred in a world arranged in a different way. [42]

47According to atheists, the world as it is could not be other than it is: everything is determined by matter and the laws of motion. According to believers, the world as it is was created according to an arrangement that God chose freely and that could have been different: this allows for future contingents, which are the events of this world connected to such an arrangement. For if we imagine another arrangement created by God, then these events would not take place. As we can see, the problem of future contingents is an abstract one: we disregard the real world and enter into God’s kitchen, where He exercises a choice between different possible arrangements. In other words, we enter into a realm of possibility prior to creation, to distinguish between the necessary and the infallible: the infallible results from the arrangement chosen by God, and the necessary is constituted by the very act of an all-powerful God’s creation of the world. D’Alembert then comes to the problem of freedom, which he expresses in terms of free future contingents:

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The existence of free future contingents, that is, those that depend on human will, is no less infallible than that of futures that are not free. For example, if, owing to God’s eternal decree, I must go to the country tomorrow, it is just as infallible that I shall make this journey as it is that it will rain tomorrow, if God has decided it. For this reason the distinction that some scholars have tried to make between free future contingents and those that are not free, is in itself an illusion, since all future contingents are in the same situation of infallibility. […] In common language, infallible and necessary are the same thing; this is not the case in theological Metaphysics. The essence of every mystery consists in a thing that is expressed by words whose apparent contradiction is an affront to reason, but that our faith teaches us is not contradictory.

49The problem of future contingents leads D’Alembert to consider all actions (going to the country) or all motion (raining) as equally infallible because they are dependent in the same way on an arrangement created by God. And since D’Alembert reduces the distinction between the infallible and the necessary to a subtlety in the language of theologians, we understand at the end of this reasoning that we are actually as free to go to the country as a falling stone is to fall, which believes itself to be free because nothing stands in its way. To conclude, D’Alembert then develops an example with a comment on the futility of scholastic debates about future contingents:

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There is a great deal of argument among scholars to determine whether two propositions of the future contingent—Pierre will die tomorrow, Pierre will not die tomorrow—are both false, when disregarding the decree of God; or if one of them is true, and the other false in this same hypothesis; a pointless, absurd question entirely worthy of the illusions of scholasticism, and one of those questions that should now be excluded from the philosophical teaching that takes place in collèges. See the article “Collège.” We might as well ask whether, when disregarding the fact that every radius of a given circle is equal, the circle continues or ceases to exist. The solution to this question (if it warrants one), is that it begins by imagining an absurdity, that of disregarding the decree of God, and therefore that it does not warrant any serious response; that for the philosopher who has the misfortune to be atheist, and therefore does not allow for the role of God in the events of the universe, one of the propositions is true, and the other false; but for us, to disregard divine decrees is to disregard the existence of God, and therefore the existence of the world, and therefore the existence of Pierre, and it is then ridiculous to ask questions about Pierre when we have disregarded his existence. These abuses of abstractions, and the futile questions to which they lead, are the great vice of scholastic philosophy.

51The scholastic debates involve such a degree of abstraction that one might prefer to assume, prudently, the existence of God, or in effect, the system of the necessity of matter and laws of motion, and the application of the principle of contradiction. Then the problem of future contingents is reduced to this: let us posit proposition A and not-A, they cannot both be true at the same time, whether this time is today or tomorrow, therefore one is true and the other is false.

52Since D’Alembert’s epistemology is one of simplicity, it consists of an application of the principle of economy to the principles of science or philosophy. The principle of economy, when applied to fields of knowledge, leads to an economy of principles. If we then recall his theory of knowledge, we are led to remove the degree of abstraction from the hypothesis of different possible arrangements of the universe, one of which is chosen by God, and we are consequently led to choose the solution of atheist materialism and to adhere to the principle of the necessity or inevitability (the two terms now appear synonymous) of all events in the universe (including our supposedly free actions).