Gottfried Wilhelm Leibniz
Seeking a reason for all that is: even asking why there is something rather than nothing, and why this world among all possible worlds.
German · 1646 – 1716
A universal mind of German , born in Leipzig in the aftermath of the Thirty Years' War. A diplomat, jurist and librarian in the service of the House of Hanover, he pursued at once mathematics (inventing, at the same time as and independently of him, the infinitesimal calculus, whence a bitter priority dispute), logic, physics and metaphysics. He published almost no major book: his thought lives in a vast European correspondence, in the Discourse on Metaphysics, the Monadology, and the Theodicy, the only one to appear in his lifetime. A critical heir of and an opponent of 's necessitarianism, he sought to reconcile the new mechanistic science with , finality and a creator God. His optimism was mocked by in Candide, yet his logic and his project of a universal language of concepts make him a recognized forerunner of modern logic.
The true atoms of nature are not material but spiritual: the real is made of monads, simple windowless substances, each of which expresses the whole universe in its own way.
Among the infinity of possible worlds, God, wise and good, necessarily chose the best: we live in the best of all possible worlds.
No substance acts on another: soul and body agree through a pre-established harmony set up in advance by God, like two perfectly synchronized clocks.
Nothing is without a : since every truth can in principle be demonstrated, one could one day settle disputes by reckoning, as two accountants do.
The free act does not escape the reason that determines it, but that reason inclines without necessitating: its contrary remains possible, so I remain free.
Justification
Against the empiricism of Locke, for whom nothing is in the understanding that was not first in the senses, Leibniz replies: nothing, except the understanding itself. The mind is not a but carries within it in potency, like veins in marble; necessary truths (logic, mathematics, metaphysics) cannot come from experience, which yields only particular cases. This is an avowed , tempered by acknowledging the role of the senses for truths of fact.
Nothing is in the intellect that was not first in the senses, except the intellect itself.New Essays on Human Understanding, II, 1
New Essays on Human Understanding, preface and book II, ch. 1 · New Essays, II, 1, §2 (the veins in the marble)
Justification
Two principles govern all knowledge: that of contradiction, which rules necessary truths, and that of , by which nothing is true without a reason why it is so rather than otherwise. If every truth has its reason, then every truth is in principle analyzable and demonstrable: this is the ground of Leibniz's rationalist , which pushes the idea to its limit by dreaming of a characteristica universalis, a universal language of concepts, and a calculus ratiocinator in which disagreements would be resolved by reckoning, as between two accountants. Certainty is no longer a distant ideal but the assignable terminus of a regulated procedure.
When a controversy arises, there will be no more need of disputation between two philosophers than between two accountants. It will suffice to take their pens, sit down, and say: let us calculate.On the Art of Combinations / Letters
On the Method of Universality; letters on the characteristica universalis · Monadology, §31-32 (principles of contradiction and of sufficient reason)
Justification
Leibniz distinguishes truths of reason, necessary, whose negation is contradictory, from truths of fact, contingent, grounded in the principle of sufficient reason. In every true proposition the predicate is contained in the subject (praedicatum inest subjecto): truth is an analytic coherence of notions, secured by the divine understanding. A correspondence share remains for truths of fact, yet the heart of the doctrine is the internal coherence of concepts.
In every true affirmative proposition the predicate is contained in the subject: praedicatum inest subjecto.Discourse on Metaphysics, §8; Generales inquisitiones
Monadology, §31-36 (truths of reason and truths of fact) · Discourse on Metaphysics, §8 (the predicate is in the subject)
1 more
Justification
A leading mathematician, physicist and logician, Leibniz holds mechanistic science to be fully valid in its order, that of efficient causes. But it cannot suffice: physics requires a metaphysical foundation (force, substances), and the order of ends escapes mechanical explanation alone. He therefore refuses reductive scientism in favor of a plurality of mutually harmonized levels of explanation.
Discourse on Metaphysics, §17-18 (force, beyond Cartesian extension) · Monadology, §79 (the two realms of efficient and final causes)
Justification
Nothing happens without a , not even creation: if God brought this world into being rather than another among the infinity of possible worlds he conceives, it is because his wisdom and goodness led him to choose the one that realizes the maximum of perfection with the least means, the best of all possible worlds. Evil is therefore not a refutation but a calculated part: God permits it where it conditions a greater good of the whole. This optimism answers the scandal of evil by turning an objection against providence into a consequence of divine perfection, the reasoning would mock in Candide through Pangloss.
It follows from the supreme perfection of God that in producing the universe he chose the best possible plan.Monadology, §55; Theodicy
Theodicy, §8-10 and §225 (the best of all possible worlds) · Discourse on Metaphysics, §3 (God does everything in the most perfect way)
Justification
If nothing happens without a , how can the act remain free? Leibniz unties the difficulty by distinguishing two necessities: absolutely necessary is that whose contrary is contradictory (truths of reason); only hypothetically necessary is what presupposes God's free choice of the best. The human act belongs to the second case: it is certain, because inscribed in the person's complete notion, yet not necessary, for its contrary remains logically possible. Motives therefore incline without compelling, and this is precisely what separates Leibniz from the necessitarianism of , where everything follows from God with geometrical necessity. This refined reconciles determination by reasons with contingency, hence a value barely on the determinist side.
Reasons incline without necessitating.Theodicy
Theodicy, §43-53 and §288 (inclining without necessitating) · Discourse on Metaphysics, §13 (the individual notion includes everything, without absolute necessity)
Justification
The self is a monad, a simple, indivisible substance whose individual notion includes once and for all everything that will ever happen to it. Personal identity is thereby secured by the permanence of this substance, a marked substantialism. Leibniz nonetheless grants a role to memory and the continuity of consciousness (apperception), adding a nuance of psychological continuity.
Monadology, §1-3 and §14 (the monad, simple substance; perception and apperception) · Discourse on Metaphysics, §8-9 (the individual notion of each substance)
7 more
Justification
For Leibniz, this world is the best of all possible worlds, chosen by God among the infinity of possibles according to the principle of the best. Nothing happens in it without a sufficient reason, and each substance, through pre-established harmony, contributes to the order and perfection of the whole. Life draws its meaning from this providential purpose that envelops it, to be recognized rather than invented.
Theodicy · Monadology, §§ 53-60
Justification
For Leibniz, no substance truly perishes: the monad is indestructible, and what we call death is only an enfolding and a diminution, not an annihilation. The rational soul moreover keeps its individuality, its memory and its moral identity, the pledge of a personal immortality required by divine justice.
Monadology, §§ 73-77 · Discourse on Metaphysics, § 34
Justification
Against Locke, Leibniz makes uneasiness, the muffled push of the small appetitions, the permanent spring of action and the engine of our advance toward greater perfection. Desire is no evil to be repressed but a positive force, provided it is enlightened and ordered toward the true good by the understanding: affirmation and reasoned sorting balance out in him.
New Essays on Human Understanding, II, 20-21
Justification
The complete notion of each individual substance contains a priori all its past, present and future predicates: to be Caesar is to possess from all eternity the essence from which everything he will do follows. The individual is thus wholly determined by his intelligible essence, conceived by God before creation, a radical essentialism.
Discourse on Metaphysics, §8-13 (the complete notion, the case of Caesar)
Justification
In the Theodicy, evil and suffering are not gratuitous scandals: God permits them because they are necessary conditions of a greater good in the economy of the best of worlds. Suffering thus fits into an overall finality that redeems it, a clearly fecund rather than abolitionist position.
Theodicy, §10-25 (metaphysical, physical and moral evil) · Theodicy, §118-119 (partial evil contributes to the good of the whole)
Justification
Happiness consists in a continual progress toward new pleasures and new perfections: felicity is not a state but a path () along which the mind grows in knowledge and power (perfectionism). Pleasure is integrated, but as the feeling of a perfection, not as a sensory end, hence a minor hedonist weight.
Principles of Nature and Grace, §18 (happiness as perpetual progress toward new pleasures) · New Essays, II, 21 (felicity as a road rather than a dwelling)
The transhumanism / bioconservatism debate on the technical alteration of human nature is anachronistic for a seventeenth-to-eighteenth-century thinker.
1 more
Justification
Leibniz's ethics lies in caritas sapientis, the charity of the wise: justice is love regulated by wisdom, willing the good of others within the order of universal perfection. This concern for others guided by knowledge unites a virtue ethics (the perfection of the soul) with a share of care (benevolence) and of duty (the rational order of the just).
Meditation on the Common Concept of Justice · Codex iuris gentium, Preface
Justification
Whatever is composite presupposes something simple, for an aggregate borrows its reality from its elements: there must therefore exist simple substances, without parts, the monads. But matter, endlessly divisible and extended, is never simple: the true atoms of nature cannot be material but must be of a spiritual order, units whose essence is perception and appetition. Extended matter then has only a derived reality, that of a well-founded phenomenon resulting from the aggregation of monads. This answers the problem of the unity of the real that Cartesian extension, always divisible, could not ground; it keeps a dualist tint, the order of bodies and that of souls remaining distinct but harmonized.
The monads have no windows through which anything could enter or leave.Monadology, §7
Monadology, §1-7 (the monads, simple windowless substances) · Letters to De Volder and Des Bosses (well-founded phenomena)
Justification
God is the supreme, necessary and personal substance, cause of the pre-established harmony and author of the choice of the best world. Leibniz proves him along several lines: the sufficient reason of the contingent universe must lie outside it; the eternal truths presuppose a divine intellect; he takes up and amends the ontological argument. This is theism in the full sense, providential and creative, not the impersonal God of , whom he opposes.
Monadology, §38-45 (God, sufficient reason, source of the eternal truths) · Theodicy, §7-8 (God, cause of the best world)
Justification
Since the monads are without windows, no substance really acts on another: the coordination of soul and body, like that of all substances among themselves, can come neither from direct influence nor from God's repeated assistance (occasionalism), but from a pre-established harmony set up at creation, like two clocks tuned in advance. Hence the rehabilitation of the set aside by mechanistic science: the realm of efficient causes (bodies) and that of final causes (souls, ends) coincide without mingling. Everything is explained mechanically in the detail of phenomena, yet the ultimate reason for their arrangement is final, inscribed in the divine choice of the best. Finalism thus takes metaphysical precedence without abolishing mechanism.
Discourse on Metaphysics, §19-22 (the usefulness of final causes in physics) · Monadology, §79 (souls act by the laws of final causes, bodies by those of efficient causes)
Justification
The subtitle of the Theodicy announces the program: to show the conformity of faith with reason. For Leibniz faith and reason can never contradict each other, since they share the same author; reason can illuminate the mysteries without exhausting them, and defend religion against its detractors. This is in the proper sense, against all fideism as against all conflict.
Theodicy, Preliminary Discourse on the Conformity of Faith with Reason
Justification
Evil is not a positive reality that God would have produced, but a privation, a limitation inherent in every finite creature (metaphysical evil), from which follow suffering (physical evil) and fault (moral evil). God does not will evil, he only permits it when it is the condition of a greater good in the economy of the whole. This is the theodicy, the word Leibniz coins to justify God against the argument from evil: he turns the objection around by showing that a world with no evil at all would be less perfect than ours, and so unworthy of a wise creator. The position is resolutely justificatory rather than tragic or rebellious.
Theodicy
Justification
Against the of , who identifies God with Nature, Leibniz upholds a creator God distinct from his creation, a transcendent orderer who chose this world among the possibles and reigns over the City of God. The world depends on him without being identical to him.
Monadology, §85-90 (the City of God, perfect monarch) · Theodicy (refutation of Spinozist necessitarianism)
3 more
Justification
For Leibniz, perception cannot be explained by mechanics: were one to enter a thinking machine enlarged like a mill, one would find only parts pushing one another, never anything to account for a perception. The life of the soul is thus not reducible to the motions of bodies; it belongs to an order of its own (final causes) harmonized with the mechanical, which leans to the emergentist side.
Supposing there were a machine whose structure made it think... on visiting it one would find only parts pushing one another, and never anything to explain a perception.Monadology, §17
Monadology, §17 (the mill argument)
Justification
The whole Leibnizian edifice makes reason the principle of true knowledge and conduct: confused petites perceptions and the passions must be clarified by the understanding, and even love is defined as the pleasure taken in another's perfection, a judgment rather than pure feeling. The leaning is intellectualist, sentiment remaining subordinate to the clarity of ideas.
New Essays, preface and II, 1 (the petites perceptions) · Codex juris gentium, preface (love as pleasure taken in another's perfection)
The contemporary debate on artificial intelligence and the possibility of a computational mind is anachronistic. The mill argument (Monadology, §17) nonetheless shows that Leibniz held perception to be inexplicable by mechanics alone, an intuition often linked to modern critiques of functionalism.