C — Certain, certitude
Original French
Quel âge a vôtre ami Christophe? Vingt-huit ans; j’ai vû son contract de mariage, son extrait baptistère, je le connais dès son enfance, il a vingt-huit ans, j’en ai la certitude, j’en suis certain.
A peine ai-je entendu la réponse de cet homme si sûr de ce qu’il dit, & de vingt autres qui confirment la même chose, que j’aprends qu’on a antidaté par des raisons secrettes, & par un manège singulier, l’extrait baptistaire de Christophe. Ceux à qui j’avais parlé n’en sçavent encor rien; cependant, ils ont toujours la certitude de ce qui n’est pas.
Si vous aviez demandé à la terre entiére avant le temps de Copernic, Le soleil s’est-il levé? s’est-il couché aujourd’hui? tous les hommes vous auraient répondu, Nous en avons une certitude entiére; ils étaient certains, & ils étaient dans l’erreur.
Les sortilèges, les divinations, les obsessions, ont été longtemps la chose du monde la plus certaine aux yeux de tous les peuples; quelle foule innombrable de gens qui ont vû toutes ces belles choses, qui en ont été certains! aujourd’hui cette certitude est un peu tombée.
Un jeune homme qui commence à étudier la géométrie vient me trouver; il n’en est encor qu’à la définition des triangles: N’êtes-vous pas certain, lui dis-je, que les trois angles d’un triangle sont égaux à deux droits? il me répond que non-seulement il n’en est point certain, mais qu’il n’a pas même d’idée nette de cette proposition; je la lui démontre, il en devient alors très-certain, & il le sera pour toute sa vie.
Voilà une certitude bien différente des autres; elles n’étaient que des probabilités, & ces probabilités examinées sont devenües des erreurs, mais la certitude mathématique est immuable & éternelle.
J’existe, je pense, je sens de la douleur, tout cela est-il aussi certain qu’une vérité géométrique? Oui. Pourquoi? C’est que ces vérités sont prouvées par le même principe qu’une chose ne peut être, & n’être pas en même temps. Je ne peux en même temps exister & n’exister pas, sentir, & ne sentir pas. Un triangle ne peut en même temps avoir cent quatre-vingt degrés, qui sont la somme de deux angles droits, & ne les avoir pas.
La certitude physique de mon existence, de mon sentiment, & la certitude mathématique sont donc de même valeur, quoiqu’elles soient d’un genre différent.
Il n’en est pas de même de la certitude fondée sur les apparences, ou sur les rapports unanimes, que nous font les hommes.
Mais quoi, me dites-vous, n'êtes-vous pas certain que Pékin existe? n’avez-vous pas chez vous des étoffes de Pékin? des gens de différents pays, de différentes opinions, & qui ont écrit violemment les uns contre les autres en prêchant tous la vérité à Pékin, ne vous ont-ils pas assuré de l’existence de cette ville? Je réponds qu’il m’est extrêmement probable qu’il y avait alors une ville de Pékin; mais je ne voudrais pas parier ma vie que cette ville existe; & je parierai quand on voudra ma vie, que les trois angles d’un triangle sont égaux à deux droits.
On a imprimé, dans le Dictionnaire Enciclopédique, une chose fort plaisante; on y soutient qu’un homme devrait être aussi sûr, aussi certain que le maréchal de Saxe est ressuscité, si tout Paris le lui disait, qu’il est sûr que le maréchal de Saxe a gagné la bataille de Fontenoi, quand tout Paris le lui dit. Voyez, je vous prie, combien ce raisonnement est admirable; je crois tout Paris quand il me dit une chose moralement possible; donc je dois croire tout Paris quand il me dit une chose moralement & physiquement impossible.
Apparemment que l’auteur de cet article voulait rire, & que l’autre auteur qui s’extasie à la fin de cet article, écrit contre lui-même, voulait rire aussi.1
1 Voyez l’article certitude, Dictionn. Enciclopédiq.
Musean translation
Mouseia’s complete machine-assisted Musean translation of the 73 articles in the 1764 first edition, made directly from the French and reviewed against the scan-collated French text. The author’s notes, quotations and verse are retained. Historical ethnic labels, including offensive terms, are retained from the 1764 text.
“How old is your friend Christopher?” “Twenty-eight; I have seen his marriage contract and his baptismal certificate. I have known him since childhood. He is twenty-eight; I have certainty of it, I am certain of it.”
Scarcely have I heard the answer of this man so sure of what he says, and of twenty others who confirm the same thing, when I learn that for secret reasons, and through a peculiar scheme, Christopher’s baptismal certificate has been backdated. Those to whom I had spoken know nothing of it yet; yet they still have certainty of what is not.
If you had asked the whole earth before the time of Copernicus, “Did the sun rise? Did it set today?” everyone would have answered: “We are completely certain of it.” They were certain, and they were wrong.
Sorcery, divination, demonic harassment were for a long time the most certain thing in the world in the eyes of all peoples; what an innumerable crowd of people who had seen all these fine things, who were certain of them! Today that certainty has faded somewhat.
A young man who is beginning to study geometry comes to find me; he is still only at the definition of triangles. “Are you not certain,” I say to him, “that the three angles of a triangle are equal to two right angles?” He answers that not only is he not certain of it, but that he has not even a clear idea of that proposition; I demonstrate it to him, and he then becomes very certain of it, and he will be so for all his life.
There is a certainty very different from the others; they were only probabilities, and these probabilities, examined, have become errors; but mathematical certainty is immutable and eternal.
I exist, I think, I feel pain: is all that as certain as a geometrical truth? Yes. Why? Because these truths are proved by the same principle, that a thing cannot be and not be at the same time. I cannot at the same time exist and not exist, feel and not feel. A triangle cannot at the same time have a hundred and eighty degrees, which are the sum of two right angles, and not have them.
The physical certainty of my existence, of my feeling, and mathematical certainty are therefore of the same value, although they are of a different kind.
It is not the same with the certainty founded on appearances, or on the unanimous reports that men make to us.
“But what,” you say to me, “are you not certain that Peking exists? Do you not have fabrics from Peking at home? Have not people from different countries, with different opinions, who have written violently against one another while all preaching the truth at Peking, assured you of that city’s existence?” I answer that it is extremely probable to me that there was then a city of Peking; but I would not wager my life that this city exists; and I will wager my life whenever anyone wishes, that the three angles of a triangle are equal to two right angles.
Something very amusing has been printed in the Encyclopedic Dictionary; it is maintained there that a man ought to be as sure, as certain that Marshal Saxe has risen again, if all Paris told him so, as he is sure that Marshal Saxe won the battle of Fontenoy, when all Paris tells him so. See, I beg you, how admirable this reasoning is: I believe all Paris when it tells me something morally possible; therefore I must believe all Paris when it tells me something morally and physically impossible.
Apparently the author of that article meant to joke, and the other author who goes into raptures at the end of that article, written against his own views, meant to joke too.1
1 See the article Certainty, Encyclopedic Dictionary.
Plain English translation
Mouseia’s complete machine-assisted Plain English translation of the same 73 articles, made directly from the French and reviewed against the scan-collated French text. The author’s notes, quotations and verse are retained. Historical ethnic labels, including offensive terms, are retained from the 1764 text.
“How old is your friend Christophe?” “Twenty-eight. I’ve seen his marriage contract and baptismal record. I’ve known him since childhood. He’s twenty-eight. I know it with certainty. I’m certain.”
The man is sure of his answer. Twenty others confirm it. They’ve barely spoken when I learn something else. For secret reasons, through some strange maneuvering, Christophe’s baptismal record was backdated. The people I spoke to still know nothing about it. Yet they remain certain of something that isn’t true.
Before Copernicus, you could have asked the whole world, “Did the sun rise? Did it set today?” Everyone would have answered, “We’re completely certain of it.” They were certain, and they were wrong.
For a long time, all peoples thought nothing was more certain than spells, fortune-telling, and harassment by demons. Countless people saw all these fine things and felt certain of them! Today that certainty has faded a little.
A young man who’s starting to study geometry comes to see me. So far, he’s only reached the definition of triangles. “Are you certain,” I ask, “that a triangle’s three angles add up to two right angles?” He says he isn’t certain at all. He doesn’t even clearly understand what the statement means. I prove it to him. Now he’s completely certain, and he will be all his life.
That’s a very different kind of certainty. The others were only probabilities. When examined, those probabilities turned out to be errors. But mathematical certainty is unchanging and eternal.
I exist. I think. I feel pain. Is all this as certain as a truth of geometry? Yes. Why? The same principle proves these truths: something can’t both be and not be at the same time. I can’t exist and not exist at once, or feel and not feel. A triangle’s angles can’t total 180 degrees and not total 180 degrees at once. That’s the sum of two right angles.
So physical certainty about my existence and feelings is worth as much as mathematical certainty. They’re different kinds of certainty, but their value is the same.
That isn’t true of certainty based on appearances or on reports everyone agrees on.
“But wait!” you say. “Aren’t you certain Peking exists? Don’t you have fabrics from Peking at home? Haven’t people from different countries, with different opinions, assured you the city exists? They’ve written bitter attacks on each other while all preaching the truth in Peking.” I find it extremely likely that a city of Peking existed then. That’s my answer. But I wouldn’t bet my life that the city exists. I’ll bet my life whenever you like that a triangle’s three angles equal two right angles.
The Encyclopedic Dictionary printed something very amusing. Suppose everyone in Paris tells a man that Marshal Saxe has risen from the dead. How sure should he be? All Paris also tells him Marshal Saxe won the battle of Fontenoy. The dictionary says he should be just as sure, just as certain, about both. Please look at this wonderful reasoning. I believe all Paris when it tells me something humanly possible. So I must believe all Paris when it tells me something humanly and physically impossible.
Apparently the author of that article meant to joke. And the other author, who gushes at the end of this article written against himself, must have meant to joke too.1
1 See the article certitude, Dictionn. Enciclopédiq.
About this section
C — Certain, certitude is part of Pocket Philosophical Dictionary by Voltaire. This page sets the French original beside 2 direct-source translations, so any line can be checked against the source. It is article 19 of 73 in the work, which is kept in the European tradition.
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