The Monadology

Gottfried Wilhelm Leibniz · 1714

Thesis

At bottom, reality is made not of matter but of countless simple, indivisible substances, monads, each a center of perception that unfolds by its own inner principle, coordinated with all the others by God in a pre-established harmony, so that the world they make up is the best of all possible worlds.

The main ideas

Whatever is composite must be made of simple things without parts. These simples, monads, are the true elements of reality.
Monads do not act on one another. Each changes only from within, according to its own nature.
Every monad perceives and strives, but in different degrees, from bare monads to souls with memory to spirits capable of reason.
Perception cannot be explained mechanically, by parts pushing one another.
All reasoning rests on two principles: contradiction, and sufficient reason, that nothing happens without a reason why it is so and not otherwise.
God coordinates all monads in advance, so each mirrors the whole universe from its own point of view.
Of all the worlds God could have created, this one is the best.

A philosophy in brief

Gottfried Wilhelm Leibniz, the German philosopher and mathematician who invented calculus independently of Newton, wrote the work now called the Monadology in French in 1714, while living in Vienna, two years before his death. It is a summary of his metaphysics in about ninety short numbered paragraphs.

Leibniz never published it, and he did not give it its title. It first appeared in 1720, in a German translation by Heinrich Köhler, who named it. At the same time in Vienna, Leibniz wrote a companion summary, the Principles of Nature and Grace.

The Monadology is extremely compressed. Many of its claims summarize arguments Leibniz made at greater length elsewhere, especially in his Theodicy (1710), so it reads less as a sustained argument than as a map of an entire system.

Implication: read it slowly, as a set of linked theses, and look to Leibniz's longer works for the arguments behind them.

Monads

The work begins with an argument. There must be simple substances, because there are compound things, and a compound is only a collection of simples. These simple substances, which Leibniz calls monads, have no parts. Because they have no parts, they have no extension or shape, and they cannot be divided. They are not tiny atoms of matter but something more like points of force or life.

Because monads have no parts, nothing can enter or leave them. In Leibniz's famous image, monads have no windows. No monad can act on another, and each changes only through an internal principle of its own.

The mechanism is that whatever is truly simple cannot be affected by anything outside it, so all its changes must come from within.

Implication: Leibniz's system shows how far a single premise, that the ultimate elements of reality must be simple, can be pushed when followed rigorously.

Perception and degrees of mind

Since monads have no parts, Leibniz must explain what distinguishes them. His answer is that each has perceptions, internal states that represent many things in a single unity, and appetition, the inner tendency that moves it from one perception to the next.

He distinguishes perception from apperception, or consciousness. Monads can perceive without being aware of it, an early statement of the idea that much mental life is unconscious.

Monads differ by the clarity of their perceptions. The simplest have only bare perception. Those whose perception is more distinct and accompanied by memory deserve the name of souls, as in animals. The highest, spirits or rational souls, can know necessary truths and reflect on themselves.

Implication: think of mind as a matter of degree rather than something a thing either has or lacks, and of much of it as operating below awareness.

The mill

In one of the most famous passages in the work, Leibniz argues that perception cannot be explained by mechanical causes. Imagine, he says, a machine that could think and perceive, enlarged to the size of a mill so that one could walk inside it. Inside, one would find only parts pushing against one another, never anything that would explain a perception.

From this he concludes that perception must belong to simple substances rather than to composite machines.

The argument anticipates a question philosophers of mind still debate: how physical processes in the brain could give rise to experience. Its interpreters disagree about whether it shows that matter cannot think, or only that we cannot see how it could.

Implication: when an explanation describes only how parts move, ask whether it has explained experience or only described its physical correlates.

Two great principles

Leibniz holds that all reasoning rests on two principles. The principle of contradiction says that whatever involves a contradiction is false. The principle of sufficient reason says that nothing happens and nothing is true without a reason why it is so and not otherwise.

These correspond to two kinds of truth. Truths of reasoning, like those of mathematics, are necessary: their opposite is impossible. Truths of fact are contingent: their opposite is possible, so they require a sufficient reason.

Applying the principle of sufficient reason to the whole series of contingent things, Leibniz argues that its ultimate reason must lie outside the series, in a necessary being that contains the reason for its own existence. That being is God.

Implication: whenever something could have been otherwise, ask why it is as it is. The demand for a reason is the engine of both science and Leibniz's theology.

Harmony and the best world

Leibniz still has to explain why monads seem to act on one another. His answer is pre-established harmony. God created all monads so that their internal developments correspond perfectly, like clocks set to keep the same time. The soul and the body agree not because one moves the other but because each follows its own laws in harmony with the other.

As a result, every monad reflects the entire universe from its own point of view, a perpetual living mirror of the universe. The many monads are many perspectives on a single world.

Since God is perfect and chose freely among infinitely many possible worlds, Leibniz argues, he must have chosen the best: the one with the greatest variety joined with the greatest order. Spirits, which can know God, form together a moral community he calls the City of God.

Implication: Leibniz's optimism is a conclusion from premises about God and reason, so to reject it, one must reject a premise, not only point to the world's suffering.

Limits

Its central doctrines are hard to accept. If no monad acts on another, all apparent causation, including between mind and body, becomes a coordinated show arranged in advance, a consequence many philosophers have found implausible.
Its optimism was famously mocked. Voltaire's Candide (1759) satirized the claim that this is the best of all possible worlds through the character of Pangloss, in the wake of the 1755 Lisbon earthquake.
Later philosophers challenged its foundations. Kant argued that Leibniz confused the objects of the senses with objects of pure thought, and Bertrand Russell argued that the system follows from a mistaken assumption that every proposition has a subject-predicate form.

A Brief History of Time — a physicist's attempt to explain why the universe exists and how it began.
Strangers to Ourselves + Redirect — modern research on the unconscious mind, which Leibniz's distinction between perception and consciousness anticipated.