--- title: "A History of Philosophy, Vol. IV: Modern Philosophy — From Descartes to Leibniz" author: "Frederick Copleston" year: 1960 shelf: "ancient-roots" purchase_url: "https://bookshop.org/search?keywords=Copleston+History+of+Philosophy+Descartes+to+Leibniz" in_stock: false related: ["copleston-history-philosophy-3", "descartes-meditations-philosophy", "damasio-descartes-error", "copleston-history-philosophy-2"] collections: [] content_type: "book-commentary" key_takeaways: - "Volume IV isolates the great Continental rationalists — Descartes, Pascal, Malebranche, Spinoza, Leibniz — as a coherent movement, deliberately holding British empiricism for Volume V and Kant for Volume VI, so the reader meets rationalism as a system rather than a survey." - "The animating problem the volume traces is substance and the relation of mind to body: Descartes' dualism opens the interaction puzzle, Geulincx and Malebranche answer with occasionalism, Spinoza dissolves it into one substance, and Leibniz reorganizes the whole into a pre-established harmony among monads." - "Copleston's Introduction refuses the textbook 'sharp break': early modern philosophy is read as both continuous with and genuinely novel against its medieval and Renaissance inheritance, correcting the rationalists' own overstated claims to have begun from nothing." references: - "Copleston, F. (1960). A History of Philosophy, Vol. IV: Modern Philosophy — From Descartes to Leibniz. Image Books/Doubleday." - "Copleston, F. (1953). A History of Philosophy, Vol. III: Late Medieval and Renaissance Philosophy. Image Books/Doubleday." - "Descartes, R. (1641). Meditations on First Philosophy." glossary_terms: - "substance" - "occasionalism" - "the geometrical method" - "monad" - "pre-established harmony" scholar_prompts: - "Copleston frames Volume IV around the mind-body problem Descartes bequeaths — two substances that cannot obviously touch. How does this seventeenth-century rupture between res cogitans and res extensa set the terms for the psychology that this library's Jungian shelf spends a century trying to heal?" - "The occasionalists and then Spinoza and Leibniz each refuse Descartes' interacting substances in favor of a single order — God as the only true cause, one substance, or a harmony fixed in advance. Read against depth psychology's insistence on the reality of psyche, which of these rationalist settlements does the least violence to inner life?" - "Copleston, writing as a Jesuit historian, gives Leibniz's theodicy and Spinoza's intellectual love of God fair and close exposition. Where does the rationalist project of grasping the whole by reason converge with, and where does it part from, the symbolic and imaginal knowing this library treats as primary?" seo_title: "Copleston's History of Philosophy, Vol. IV: Descartes to Leibniz | Seba" seo_description: "On Copleston's fourth volume — the Continental rationalists from Descartes to Leibniz: substance, the mind-body problem, occasionalism, Spinoza's monism, and Leibniz's monads." --- **One Book for the Rationalists** The fourth volume opens with a decision the reader should notice. Copleston had hoped, he explains in the preface, to carry the story from Descartes through Kant in a single book; the material forced him to divide it into three. Volume IV takes only the great rationalist systems of the Continent in the pre-Kantian period — Descartes to Leibniz — leaving British philosophy from Hobbes to Hume for Volume V and the road to Kant for Volume VI. The gain is concentration: rationalism is presented not as one lane in a survey but as a movement with its own logic, worked out at length philosopher by philosopher rather than problem by problem. The cost, which Copleston names himself, is that a reader given detailed portraits of separate thinkers may lose the general picture — a risk the Introduction sets out deliberately to offset. **Continuity and Novelty** That Introduction is the volume's interpretive spine, and its argument is a refusal of easy alternatives. The older textbook picture made modern philosophy begin with Descartes as a clean break from the schools; a corrective generation of scholars then emphasized how much of medieval and Renaissance thought carried forward. Copleston will let neither claim harden into a rule. Continuity can be observed in the philosophical sphere as in the political and social; discontinuity has been over-stated by philosophers eager to advertise their own novelty. But continuity can be over-emphasized in turn, and the honest account holds both elements together rather than choosing between the assertion of a sharp rupture and the assertion of seamless descent. This balanced posture — sober, source-fed, unwilling to flatter either the rationalists' self-image or the reaction against it — is the register in which the whole volume is written. **Substance and the Mind-Body Problem** The connective thread that keeps the separate portraits from scattering is the problem of substance, and within it the relation of mind to body. Descartes receives the volume's longest treatment — the idea of method and the methodic doubt, the cogito, the criterion of truth and the proofs of God's existence, and then the fateful division of the world into thinking substance and extended substance, whose interaction he could assert but not explain. From that unresolved seam the rest of the volume follows almost as a series of answers. Pascal breaks off toward the heart and the limits of the geometrical method; Geulincx and the Cartesians confront the problem of interaction directly; Malebranche makes God the only true cause and locates the vision of eternal truths in God, so that finite things are occasions rather than agents. Spinoza then removes the difficulty at its root: if there is only one substance, of which thought and extension are attributes, the puzzle of how two substances communicate simply dissolves — and with it, worked out by the geometrical method, come the conatus, the passage from bondage to freedom, and the intellectual love of God in which the ethics culminates. **Leibniz and the Rationalist Summit** The volume closes on Leibniz, in whom Copleston finds the rationalist ambition at its most architecturally complete. The distinction between truths of reason and truths of fact, the principle of perfection, the identity of indiscernibles and the law of continuity organize a world of simple substances — monads — each unfolding from within, without windows onto one another. Where Descartes left interaction unexplained and the occasionalists made God intervene, Leibniz fixes the correspondence in advance: the pre-established harmony synchronizes soul and body, and every monad, as a mirror of the whole, requires no causal traffic to agree with the rest. The final chapter turns this metaphysics toward God — the ontological argument, the argument from eternal truths, the argument from the harmony itself — and to the problem of evil, where the theodicy and the reading of progress and history bring the rationalist project to its most confident reach for the whole by reason alone. Read as series architecture, Volume IV is the panel in which the modern subject, opened at the close of Volume III, first tries to think its own foundations without the medieval scaffolding. For this library the volume earns its place less as doctrine than as diagnosis: the split of mind from body that Descartes installs is the wound the Jungian and the neuroscientific shelves alike keep returning to, and Copleston gives the exact terms in which it was first made.