Editor’s Note: This is the fifth in a series of essays on the origins of liberalism and conservatism.
By Victor Nuovo
Of all the great personages of the Enlightenment, Denis Diderot (1713-1784) is probably the most modern; that is, his opinions anticipate all of modern liberalism.
He was a philosophical naturalist, a materialist, a proponent of natural science, an atheist, a proponent of the secular state and of a secular morality to go with it, an advocate of free love and gender equality, a cultural relativist, a defender of religious toleration and of freethinking, an opponent and harsh critic of colonialism and of its notorious consequences, namely, slavery and economic exploitation, and a commentator on their ill effects upon non-European society and cultures.
He was the first writer to explore what he considered to be the inevitable entanglement of Christianity and sexuality, and its unhappy psychological effects, and to describe its tragic consequences: unbearable guilt, sadomasochistic cruelty, and madness. It should also be noted that he describes these things with great empathy and concern.
However, he gained fame not so much as an author, but as an editor. He edited the Encyclopédie, the great French Encyclopedia of the Sciences, Arts, and Crafts, which became a monument of the age, a treasury of enlightened learning. Thus, he is more often thought of as an enabler of the Enlightenment than one of its major figures, such as Rousseau or Voltaire. Because of that, his writings are often ignored. Besides, his philosophical and critical writings are more in the form of articles — many written for the Encyclopédie; they are fragmentary and scattered over a broad range of subjects. He left his readers with the task of unifying his thoughts.
There is, I believe, a common theme or point of view that unites them, and it is central to modern liberalism. It is Diderot’s empirical naturalism. It is evident in almost all his writings, in his choice of topics and what he wrote about them. I will try to illustrate this by commenting on two short works: one, entitled “Letter on the blind, for the use of those who can see,” and an article on natural right written for the Encyclopédie.
Diderot’s “Letter on the blind” consists of reflections on a theme that may seem very remote from politics. It concerns what has come to be known as “the Molyneaux Problem,” a hypothetical question posed by William Molyneaux in a letter to John Locke dated 7 July 1688. Molyneaux was concerned with the truth of Locke’s claim that all the ideas that occupy our minds originate from sensory experience. Now suppose a man born blind were to have his sight restored. (The practice of the surgical removal of cataracts was just beginning.) Here is the problem as Locke summarized it:
“Suppose a Man born blind, and now adult, and taught by his touch to distinguish between a Cube, and a Sphere of the same metal, and nearly of the same bigness, so as to tell, when he felt one and the other; which is the Cube, which the Sphere. Suppose then the Cube and Sphere placed on a Table, and the Blind Man to be made to see [i.e. his sight surgically restored]. I ask, Whether by his sight, before he touched them, he could now distinguish, and tell, which is the Globe, which the Cube.”
Molyneaux thought he could not, and, after some hesitation, Locke agreed; the once blind man, now with his sight restored, would first have to learn from experience that sight and touch concur. It is a fascinating problem that some might argue is still unsolved; it has recently drawn the attention of neuro-scientists.
Diderot applies the question to moral ideas and sentiments. The Enlightenment is commonly described as the Age of Reason, but it was equally an age of feeling, a sentimental age. It was, after all, also the age of Grand Opera. Diderot believed that moral rules are without effect, without empathy.
For example, the Golden Rule, “Do unto others, as you would have others do unto you” would have little effect unless we had some feeling for the feelings of others. In this connection, he believed that the face is the most expressive part of the body, even more than the voice, than sounds of laughter, cries, or screams, and that among facial features, nothing is more expressive than the eyes — themselves as instruments revealing a whole variety of human emotions: joy, hatred, fear, anguish, boredom, contempt and more.
Even apart from the face, the mere bulk of another living animal affects us, although its affect appears to diminish with its size. “We feel for a horse in pain, and squash an ant without giving it a moment’s notice.” The moral sentiments do not originate in the inner sanctum of our self, rather we learn them from seeing others, and there develops a concurrence between what we see in others and what we feel for ourselves. Here, he supposed, is the origin in nature of moral sentiments and of morality. And because justice, a moral principle, is the principle politics; politics must have the same origin.
What of the man born blind, who does not see the faces of others; who does not see an animal writhing in pain? He is not without feelings, and because he does not live as a hermit, but in society with others, he develops capacities that seem to those who have vision to be remarkable in sensitivity and discernment: his sense of place, of direction, of order, especially the mathematical order of things — Diderot remarks that a person born blind can develop through touch a sense of symmetry, but not of beauty. Yet, he conjectures, pity may be less well developed in those born blind just because they cannot see the faces of others.
On the other hand, they have greater self-mastery, and are less inclined to self-pity, because living in a world shaped by people with sight, they are always reminded of their deprivation. This may seem paradoxical, but it is not. All these things remain open questions, like Molyneaux’s problem. But it puts beyond doubt our great dependence on the senses for information, without which our moral senses would not develop or would develop differently.
How does this all relate to the origin of civil society? Diderot agrees with Rousseau; the individual person must be transformed into a citizen. This transformation must be an act of each individual, an act of rational choice.
Diderot’s account of it is striking in its originality. Every individual is faced with a choice between pure selfishness and conforming one’s will to the will of the whole.
He imagines the selfish person to be at war with the human race, for he desires all praise, all riches, all grand attributes for himself — much like a selfish child all of whose wants are satisfied on demand and whose demands persist when they become adults and hold high public office.
Others quite properly regard such an egoistic person with indignation. But their revulsion is warranted only as an expression of a universal will, the will of a society of persons who choose to live under a universal law that applies to everyone in the same way and with the same rigor. In short, it is a law that is just only if it is applied with equity to all.