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PhilosophersDenis Diderot

Denis Diderot

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Enlightenment · Materialism1713 – 1784 FranceEnlightenment philosopherMaterialistEditor of the EncyclopédieWriter of dialogues
Letter on the Blind, 1749

Blind Saunderson: order without a designer

What it claims

The order of nature does not prove that a God designed it, and God would not explain it any better: about the origin of things, better to admit our ignorance.

Why

Another explanation is possible: matter produced many beings and only the well-formed ones lasted, with no designer.

Valid with an implicit premise

A clergyman shows a blind mathematician on his deathbed the wonders of nature: they prove God. The blind man answers that this order may come from sorting: matter produced countless forms, the failed ones died out, and only those able to live and reproduce remained. Note: Saunderson existed, but this speech is invented by Diderot. It is his voice, behind a mask. And Saunderson does not say "God does not exist": he even finds it rash to deny what Newton accepted. He asks us to admit our ignorance. The story ends on a puzzle: in his delirium he cries "O God of Clarke and Newton, have mercy on me!" Caution in the face of censorship, or real doubt? Readers disagree. Diderot himself would become an atheist.

P1The order of the world proves a designer only if no other explanation of that order is possible.
P2Yet another explanation is possible: at the start, matter in motion formed a host of beings, many malformed; these died out, and only those able to survive and reproduce remained.
P3This explanation fits what we observe: the order is not perfect, malformed beings are still born, like Saunderson himself, who is blind.
P4 · implicit premiseAn explanation that is possible and consistent with the facts is enough to strip the design argument of its force as a proof, even if it is not demonstrated.
P5Calling on a God to explain the order explains nothing further: it cuts one knot with a knot even harder to untie.
Therefore the order of nature does not prove that a God designed it, and God would not explain it any better: about the origin of things, better to admit our ignorance.

click a premise to reject it

If you accept every premise, logic forces you to accept the conclusion. So the debate is about the premises.
Checked by a logic solver: the premises cannot all be true while the conclusion is false.
Without the implicit premise: Without P4, the computer finds a case where natural sorting is possible and fits the facts, yet the order still proves a designer, because this other explanation, merely possible, does not count.
Valid with P4. The conclusion has two parts. P1 to P4 strip the order of the world of its force as a proof; P5 says that God, in any case, would explain nothing further. The decisive point is P4: a possible explanation is enough, not a demonstrated one. Defenders of design mostly attack there, and P1: for them, the design argument need not rule out every other explanation, it is enough that a designer is the best one. They also attack P2 (is this sorting really possible?) and P5 (is God really a new knot?). Note: the conclusion does not say that God does not exist. It says that this proof fails and that we must admit our ignorance. That is why we file this argument under agnosticism.
Analogy. You find in a drawer only keys that open the door. Did someone choose them? Maybe. But if you know that thousands of keys were tried and all those that did not open were thrown away, the drawer no longer proves that a locksmith made them to measure.

Objections

4

Each objection is a conversation: click to see who replies and where the debate stands.

Diderot himself, three years earlier (Philosophical Thoughts, 1746) 1746 · attacks premise 2

A butterfly's wing, the eye of a tiny insect show an intelligence as clearly as Newton's books show that he thought. And experiment proves that rotting matter never produces anything organised on its own: matter does not arrange itself into living beings.

Diderot replies
Diderot His answer in 1749, through Saunderson
I grant you the admirable order of the world as it is today. But about its first state you are as blind as I am: no one saw how living beings were formed, and nothing forbids us to think there was first a multitude of failures.
Where the debate stands (our summary)Between 1746 and 1749 Diderot changes position: his 1749 answer no longer disputes the present order of the world, but the idea that we know how it was formed. The basic disagreement is whether order can arise from matter alone, a possibility Darwin made precise for living things.
William Paley 1802 · attacks premise 4

Sorting only explains the disappearance of failed forms, not the appearance of organs as precise as the eye. Saying an order is "possible" by chance is not enough: we see nowhere these countless failed attempts, while the eye shows every sign of a tool designed for seeing.

no reply
summary: their text is not yet in our corpus see the argument
No reply possible: objection raised in 1802, after the author's death (1784).
Where the debate stands (our summary)Paley was answering the idea of a one-off sorting, not Darwin's cumulative selection. The debate on the eye, intermediate stages and irreducible complexity continues in Paley's watch argument.
Richard Swinburne 1968 · attacks premise 2

Swinburne grants that Darwin explained the order of living things, the arrangement of their organs, by natural laws: on this point Saunderson's idea became science. But this sorting itself presupposes another order, which nothing sorts: the regularity of the laws of nature, which hold everywhere and always. It is on this order that Swinburne rests the design argument.

no reply
see the argument
No reply possible: objection raised in 1968, after the author's death (1784).
Where the debate stands (our summary)Both camps agree that natural selection explains the adaptation of living things. The disagreement concerns the order of the laws themselves: does it call for a designer, or is it a basic fact that is not explained? The debate has continued with the fine-tuning of the constants (design, a multiverse, or a brute fact). Open point.
Leibniz (the necessary being) 1714 · attacks premise 5

God is not a new knot like the elephant or the tortoise. Each thing in the world depends on another, and we can always ask why. But God is a necessary being: he bears in himself the reason for his existence. So the question "and who made him?" no longer arises. That is where we can stop.

a defender replies
see the argument
We have not yet found a direct reply by Diderot in the texts.
David Hume defender of the argument · 1779 · Cleanthes, in the Dialogues (part IX)
In the Dialogues, Cleanthes, though a defender of design, answers Demea, who puts forward an argument of the same type. Whatever we conceive as existent we can also conceive as non-existent, God included: so no being is necessary in the sense that its non-existence would be a contradiction. And if necessity lies in unknown qualities, why may not the material universe itself be the necessarily existent being? We do not know all the qualities of matter.
Where the debate stands (our summary)The basic disagreement concerns the notion of a necessary being: some judge that such a being ends the series of "whys", others that one does not see why this necessity should belong to God rather than to the material world. Open point.