🔷 Metaphysics in Medieval Philosophy
Medieval metaphysicians treated the study of being (ens) as the foundation for all knowledge. Their careful distinctions — between essence and existence, act and potency, form and matter — created a durable map for thinking about God, the soul, identity, causality, and the purposefulness of the world.
Why Metaphysics Mattered
For thinkers such as Thomas Aquinas and Avicenna, metaphysics (or “first philosophy”) investigates being as such — what it means for anything to exist. Unlike modern reductive approaches, medieval metaphysics aimed to show how metaphysical categories ground theology, ethics, psychology, and natural philosophy. Its concepts supplied answers to questions about God, causation, human identity, and the unity of reality.
Key Concepts — Quick Glossary
- Being (ens) — the fact of existing; the primary subject of metaphysics.
- Essence (quidditas) — a thing’s “whatness” (what it is).
- Existence (esse) — the act of being; that a thing actually is.
- Act & Potency — actuality (what is) vs. potentiality (what can become).
- Form & Matter — form organizes, matter underlies; together they compose substance.
- Substance vs Accidents — a substance exists in itself; accidents are properties it has.
- Necessary vs Contingent — God (necessary) vs. created beings (contingent).
A central medieval insight
Creatures have a real distinction between essence and existence: what a thing is (essence) is distinct from the fact that it is (existence). Only a necessary being (God) unites essence and existence.
Essence & Existence: Avicenna, Aquinas, Maimonides
Avicenna argued that essence and existence are distinct in all created things: existence is an “addition” actualized by a cause. Aquinas echoed and refined this: in creatures essence stands in potency to existence; existence is the act that perfects essence (actus essendi). Maimonides similarly held that human reason can demonstrate God’s necessity, while God alone has essence identical with existence. These moves supported proofs for a first cause and explained contingency, change, and dependence.
Act & Potency, Form & Matter
Drawing from Aristotle, medievals used act/potency to describe physical change and metaphysical structure. Matter is the potential substrate; form actualizes it. In living beings the soul functions as form, organizing matter into a unified, living substance.
Substance & the Soul
The rational soul was taken to be the substantial form of the human: not merely an emergent property but a principle of life and intellect that accounts for personal identity across bodily change.
Practical metaphysical note
The distinction between essential nature and accidental features offers a durable way to think about identity: what remains at a person’s core despite life’s changes.
Universals: Realism, Conceptualism, Nominalism
Medieval debates about universals asked whether shared natures (like “humanity”) exist really or only as names. Aquinas advanced a moderate realism (universals exist in things and as ideas), Scotus developed subtle formal distinctions, and Ockham later pushed nominalism (universals as linguistic signs). These disputes shaped medieval ontology and our ideas of sameness and individuality.
Causality, the Cosmos, and Hierarchies of Being
Scholastics adopted Aristotle’s four causes and emphasized God as First Cause and exemplar. The cosmos was often pictured as a graded hierarchy — from pure act (God) to angels, humans, animals, plants, and matter — the Great Chain of Being. This ordered picture supplied metaphysical reasons for teleology, moral order, and human dignity.
Practical Insights for Modern Life
Discern your essentials
Ask what is essential (your values, virtues, talents) and what is accidental (roles, possessions). Nurturing your essence builds steady identity amid change.
Actualize potential
Treat act/potency as a metaphor for growth: latent capacities become real by discipline, education, and habituation — just like a seed becomes a tree.
Seek ordered purpose
Even if you reject medieval teleology, thinking in terms of ends (knowledge, virtue, community) helps make daily life intelligible and meaningful.
Balance unity & individuality
Recognize shared human features (universals) while honoring each person's particularity — a balanced view that supports empathy and respect.
Conclusion
Medieval metaphysics supplied a rigorous vocabulary for asking what it means to be. Whether one accepts its theological premises, its distinctions — essence/existence, act/potency, form/matter — remain powerful tools for thinking about identity, causation, and purpose. Far from antiquarian curiosities, these ideas can still illuminate modern concerns about personal development, social order, and the search for meaning.
Select Sources & Further Reading
- Internet Encyclopedia of Philosophy — entries on Aquinas, act and potency, and Duns Scotus
- Stanford Encyclopedia of Philosophy — articles on universals, Avicenna, and medieval metaphysics
- Primary texts: Aquinas, De Ente et Essentia; Avicenna, selections from Al-Shifa’; Maimonides, Guide for the Perplexed.