Denis Diderot (1713–1784) solidified his position as a central figure in the Enlightenment with unorthodox thinking which was informed by his scientific leanings—one of such ideas was his staunch materialism. Diderot’s place as a materialist would inform many of his other beliefs (viz. determinism, his ethical views, etc.); but, the focus of what’s to follow is his conception of materialism and how he argues for the validity of the view through dialogues in D’Alembert’s Dream.
There are three prevailing theses regarding the world and how it’s constituted (the same three that prevailed during Diderot’s time): materialism, dualism and idealism. Materialists insist that everything in the world—including the mind—is physical; dualists insist that there are two fundamental “types” of things in the world: those that are physical and those that are mental, fragmenting persons’ constitution into two distinct types: mind and body; idealists think there are only mental things in the world, directly opposing materialism (for my purposes, I will be focusing on materialism and dualism). Diderot rejected dualism, choosing to instead prioritize the natural world and disregard supernatural explanations appealing to things like souls or divine intervention.
A typical materialist believes that the world is full of inert matter—Diderot’s materialism was not typical; he believed that matter was self-organizing and, more radically still, he believed matter was able to think/feel (to a certain extent). In D’Alembert’s Dream he used fictitious dialogues between four characters (Diderot, D’Alembert, L’Espinasse, and Bordeu) to further explore this idea of self-organizing matter and how the distinctions we make between material things are arbitrary; that is to say, in Diderot’s view, everything in the world is in a constant state of flux and, given adequate time, matter may organize itself into any imaginable form: “Everything changes, everything passes away—only the Whole endures. The world is perpetually beginning and ending; every moment is its beginning and its end; there has never been any other kind of world, and there never will be any other.” (Diderot 117)
The argument for this version of materialism was made by Diderot using his characters in D’Alembert’s Dream as mouthpieces. An important distinction they discuss is that between continuous and contiguous; the first time this distinction is made is in the following passage: “And how does this continuity arise? … Just the way a drop of mercury melts into another drop of mercury, one living, sensitive molecule can melt into another one … Before assimilation, there were two molecules; afterward there was only one….” (Diderot 110) Making this distinction was important for Diderot’s materialism because it illustrates how he thinks of matter and its organization, and how different his thinking was from contemporary dualists and materialists. Diderot’s central claim is that matter’s appearing contiguous (i.e. separate objects) is illusory, and that, really, all matter is continuous (i.e. inseparable objects).
This continuity/contiguity distinction is explicated even further when the characters L’Espinasse and Bordeu begin discussing the nature of bees and how they seem contiguous but act mostly in accordance with each other; how “the whole cluster [of bees] will stir, quiver, change its shape and location, the cluster will make a noise … so that anyone who had never seen such a cluster formed would most likely mistake it for an animal with five or six hundred heads and ten or twelve hundred wings….” and to push the analogy further, we could imagine “…how the bunch of bees could be transformed into a single, unique animal[:] … soften the material in the feet by which they cling to one another, make them continuous instead of contiguous.” (Diderot 112) It seems, according to Diderot, that the human body (its organs, etc.) is much like hundreds of bees working together; but, even more radical is the notion that each human body is also like a single bee in a much larger continuous hive.
A surprising consequence of this version of materialism (vital materialism) (Stoljar) is that the matter present in the world is necessary to explain everything—including things like thoughts and senses; to Diderot, this means that certain properties of matter are, in themselves, thinking and sensing. This doesn’t mean, though, that everything is sensing/feeling all the time; rather, it means that everything has the potential to be organized in such a way to sense and feel: “If we think of animals as sensitive instruments, then one of them is perfectly comparable with another that has been put together on the same plan—all will have the same strings and their keys will respond in the same way to joy and sorrow, hunger and thirst, anger, admiration and fright.” (Diderot 104) So, in this way, when matter organizes itself into a certain formation (e.g. a human being), sensing, feeling, and thinking emerge; and, since matter is continuous (as opposed to contiguous), there is no real difference between living/non-living things other than the mere complexity of the matter that’s been arranged.
This view of continuous, self-organizing matter, all of which had the potential to sense/feel when organized in a particular fashion, was what set Diderot apart from his contemporaries and their views on the subject—it left no room for anything other than worldly explanations. This left many of Diderot’s contemporaries asking how God fit into the larger framework, but Diderot did not concern himself with including God in this view. Diderot’s materialism was the framework which informed his thinking on most other topics (viz. ethics, metaphysics, aesthetics, etc.) and naturally led him to a deterministic conclusion, since everything is matter and causally related.
Fortunately for Diderot, the Enlightenment was an era chock-full of people desiring to understand the world in a naturalistic way, without appealing to the need for supernatural forces and explanations with mysterious origins. Diderot’s materialist framework was ahead of its time, setting the stage for ideas like emergentism about consciousness and presented thoughts resembling evolutionary theory. In D’Alembert’s Dream, Diderot depicts a hyper-rational mathematician/physicist D’Alembert slowly become convinced that there is nothing other than the various arrangements of matter and, in so doing, presents an argument for a specific flavor of materialism to the reader. In Diderot’s world, matter is self-organizing, continuous, and always changing forms; so, when D’Alembert raised the challenge: “…I don’t see very well how one can make a physical object change from a state of latent consciousness to a state of active consciousness”, Diderot retorted by saying, “It is something that happens every time you eat a meal.” (Diderot 94)
Glossary of Terms
- Materialism – “The general idea is that the nature of the actual world (i.e. the universe and everything in it) conforms to a certain condition, the condition of being physical.” (Stanford Encyclopedia of Philosophy)
- Vital Materialism – Diderot’s specific materialism that proposes matter that is active, self-organizing, and not inert.
- Dualism (more specifically, substance dualism) – “It is agreed that by ‘substance dualism’ we mean the view that minds and bodies are fundamentally distinct kinds of substances.” (Stanford Encyclopedia of Philosophy
- Determinism – “The idea that every event is necessitated by antecedent events and conditions together with the laws of nature.” (Ibid.)
- Continuous – “To be continuous is to constitute an unbroken or uninterrupted whole, like the ocean or the sky. A continuous entity—a continuum—has no “gaps”.” (Ibid.)
- Contiguous – to be bordering/adjacent, but not continuous.
- Emergentism (about consciousness) – “A property is emergent if it is a novel property of a system or an entity that arises when that system or entity has reached a certain level of complexity and that, even though it exists only insofar as the system or entity exists, it is distinct from the properties of the parts of the system from which it emerges.” (Internet Encyclopedia of Philosophy)