Discourse on Metaphysics

Context and Aims

Gottfried Wilhelm Leibniz’s Discourse on Metaphysics (Discours de métaphysique) is a compact treatise written in 1686, probably intended for his correspondent, the theologian Antoine Arnauld, rather than for immediate publication. It presents in relatively accessible form several of Leibniz’s most influential metaphysical theses at a formative stage of his system, anticipating later works such as the Nouveaux essais and the Monadology.

The Discourse aims to reconcile metaphysical rationalism with Christian theology, defending both the perfection of God and the meaningfulness of human freedom and morality. Leibniz frames many of his claims as clarifications or corrections of earlier thinkers, especially Descartes and Scholastic Aristotelianism, and he seeks a middle path between strict occasionalism and robust creaturely causation.

Central Doctrines and Arguments

Leibniz structures the Discourse in a series of numbered sections, each developing a key metaphysical claim. Several themes have become canonical reference points in discussions of his philosophy.

1. God’s perfection and the nature of divine choice

A guiding idea is that God is absolutely perfect, and that this perfection governs God’s choice of which world to create. Leibniz maintains that God, as a perfectly wise and good being, always chooses the best possible world—a world whose overall order and harmony are unsurpassed, even if it contains local imperfections or moral evils. According to this view, apparent defects are to be understood as contributing to a larger, optimal structure that finite minds cannot fully survey.

In the Discourse, this doctrine is still formulated in a relatively tentative way, but Leibniz already links it to his conception of divine intellect: God has an infinite grasp of possible essences and “combinations” of things, and the act of creation is the selection of one complete, harmonious set of compossible possibilities.

2. Individual substances and complete concepts

One of the most distinctive claims of the work is the “complete concept” theory of substance. Leibniz argues that every individual substance—for example, the person Socrates—can be associated with a complete concept that includes everything that will ever truly be predicated of that individual. In this sense, the entire history and character of a substance are grounded in its concept as understood by God.

This view has important consequences:

• Truths about an individual (such as “Socrates will drink hemlock”) are, in some sense, analytically contained in the complete concept of that individual.
• Each substance is metaphysically independent, not in the sense of existing without God, but in that its identity and unfolding states are rooted in its own internal nature rather than being determined by external interaction.

Critics have argued that this threatens human freedom, since future actions seem fixed in a concept known by God. Leibniz responds by distinguishing between necessity and certainty: while God’s knowledge of the complete concept makes future events certain, they are not thereby metaphysically necessary, since their denial does not involve a logical contradiction.

3. Substantial form, activity, and internal principle

Leibniz rejects a purely mechanistic picture of the world consisting only of extended bits of matter in motion. In the Discourse, he reintroduces the idea of substantial forms—internal principles of unity and activity—into early modern philosophy. For him, a genuine substance must have an inner source of change; it is not merely a passive bearer of externally imposed motions.

This leads toward his later doctrine of monads, though the term itself does not yet play a major role here. The Discourse already maintains that:

• True unity is found in simple, non-extended substances, not in arbitrarily assembled collections of parts.
• These substances possess perceptions and appetitions (tendencies toward further states), making them intrinsically active rather than inert.

4. Pre-established harmony and causation

The Discourse marks an important stage in the formulation of pre-established harmony, Leibniz’s account of the apparent interaction between mind and body and, more generally, among created substances. Rejecting both Cartesian interactionism and Malebranchean occasionalism, Leibniz proposes that:

• Each substance evolves according to its own internal laws or concept.
• There is no genuine causal interaction between substances; rather, there is a divinely instituted coordination among them.
• This coordination is so exact that the inner states of one substance correspond to those of others, as if they interacted, much like perfectly synchronized clocks.

Thus, God’s original creative act pre-establishes a harmony between all substances, preserving both divine sovereignty and the apparent regularities of experience, while avoiding direct divine intervention at each event.

5. Free will, contingency, and moral order

Another major focus is the reconciliation of divine foreknowledge and decree with human freedom. Since all truths about an individual are contained in its complete concept and are known by God, the danger of fatalism is pressing. Leibniz’s strategy in the Discourse involves several distinctions:

• He differentiates necessary truths (grounded in the principle of contradiction) from contingent truths (based on the principle of sufficient reason but not logically necessary).
• Human actions are contingent: although there is always a sufficient reason why a free agent chooses as they do, the opposite remains logically possible.
• God “inclines without necessitating,” ordering the world and a person’s nature such that free choices fit into the best overall plan, without removing the agent’s authorship of those choices.

Leibniz argues that this framework preserves moral responsibility and justifies divine reward and punishment, since agents act from internal principles and reasons, not from external compulsion.

Reception and Influence

Because the Discourse on Metaphysics remained unpublished until the nineteenth century, it did not directly shape early modern debates in the way that Descartes’s or Spinoza’s main works did. Nevertheless, it has become a crucial text for later interpreters attempting to reconstruct Leibniz’s system and its development.

Scholars use the Discourse to trace the evolution from Leibniz’s more Scholastic early period to his mature idealism and monadology. The work’s articulation of complete concepts, pre-established harmony, and the best possible world has also been central in discussions of:

• The problem of evil, particularly in assessing the philosophical content of Leibniz’s theodicy.
• Modal metaphysics, as commentators analyze his understanding of possibility, necessity, and contingency.
• The history of rationalism, since the Discourse offers a bridge between Cartesian metaphysics and later German idealism.

Interpretive debates continue over how closely the Discourse matches Leibniz’s later published positions, how to reconcile the complete concept doctrine with robust human freedom, and whether pre-established harmony implies a form of occasionalism in disguise. Despite such disputes, the work is widely regarded as one of the most illuminating entrances into Leibniz’s metaphysical project and its distinctive synthesis of logic, theology, and science.