Cartesianism

Time is substantival and infinite, the continuous medium in which created substances endure under God's ongoing conservation. It is one-dimensional, continuous, linear, and uni-directional, and Descartes famously construes God's sustaining activity as a continual re-creation at each moment, which imparts to time a deeply theological texture. Freedom is non-deterministic because the human will, although finite, is a genuine cause whose acts of assent are not necessitated. The geometric clarity that Cartesian physics demands of space carries over to its picture of duration.

Space, identified with extension itself, is substantival, infinite, three-dimensional, and locally Euclidean. There is no genuine vacuum in the Cartesian universe: where there is extension there is matter, and the plenum is articulated into a single continuous geometric whole. Curvature is flat as a matter of principle, since Descartes's geometry is the classical one, and locality holds because bodies act on one another by contact through the surrounding plenum. The mathematisation of space is precisely what makes the new physics possible.

Matter is substantival, infinite in extent, three-dimensional, and conserved by God's ongoing creative activity. Its essence is extension alone, stripped of all sensible qualities that the scholastic tradition had attributed to it, which permits a thoroughly geometric and mechanical physics. Conservation is grounded both in God's constancy and in Descartes's conservation principle for the quantity of motion. Locality holds because all material interaction proceeds by contact within the plenum, and the entire material world is intelligible to clear and distinct geometric thought.

The Cartesian observer is a thinking thing — a res cogitans whose existence is the first and most certain item of knowledge, secured by the cogito of the 'Meditations' (1641). Although ordinarily joined to a body, the soul is metaphysically distinct from extended matter, so the observer is rated as Disembodied in the strict metaphysical sense even as it operates through embodied perception. Knowledge of one's own ideas is immediate and indubitable, while knowledge of external bodies is mediated by ideas and underwritten by God's non-deceptive nature. Retention is partial because finite minds err and forget. Observers are plural because there are many finite souls, each capable of clear and distinct thinking, and each actively willing assent or suspending judgement on the ideas before it.

Energy is substantival and infinite — Descartes's plenist physics treats motion as a real quantity directly conserved by God, the first cause whose immutability guarantees the laws of nature. Conservation is total: God preserves the total quantity of motion in the universe at every instant, and what looks like local loss is only redistribution among the parts of extended substance. Dispersibility is reversible in the Cartesian picture: physical processes in a perfectly elastic plenum admit time-symmetric description, and irreversibility appears only at the phenomenal level. Mind, as a distinct substance, does not exchange energy with body in the modern sense — the interaction problem that haunts the dualist is precisely the puzzle of how thought can deflect motion without violating its conservation.

Information for the Cartesian is borne by ideas in the mind and by the geometric properties of bodies in extension, both of which are substantival and ultimately grounded in God's creation. Granularity is continuous because thought and extension alike are conceived as continua rather than as bundles of atoms. Information is conserved because God's veracity guarantees the stability of clear and distinct truths and because the geometric structure of the world does not vanish. The framework distinguishes scales: cosmic information is conserved through the divine sustenance of creation, and personal-identity information is also conserved because the immortal soul, as argued in the 'Sixth Meditation', persists beyond the dissolution of the body.