The substance-ontological concept of person determines the person as an individual substance of rational nature. It goes back to Boethius, who formulated the classical definition: naturae rationalis individua substantia — “the person is a unique self-standing being of rational nature” (cf. Bexten 2017, pp. 117 ff.). Thomas Aquinas takes over and deepens this definition. The person is “the most perfect thing in the whole of nature” (perfectissimum in tota natura). To be a person is the highest mode of being.
Three marks are essential. First, substantiality: the person is an ens per se, a being standing in itself, not a mere bundle of properties. Second, rationality: the person has rational nature as its essence, not merely as a contingent property. Third, individuality: every person is unique and irreplaceable, a someone.
In contrast to the empirical-functionalist concept of person, the substance-ontological concept determines personhood through being, not through doing. According to agere sequitur esse, person-behavior is a consequence of personhood, not the reverse. Berthold Wald, in Substantialität und Personalität (2005) (German), reworked the line of intellectual history from Boethius through Thomas to Spaemann anew and defended the rehabilitation of the concept of substance against its modern critics.
The dissertation advances as its result the substance-ontological-relational concept of person (Bexten 2017, p. 129). The person is spiritual substance in the body in relation. The truth of the relational concept of person is thereby integrated without abandoning the substantial foundation. In the philosophical tradition this concept of person is found in Aristotle (doctrine of substance), Alexander of Hales (person as a concept of dignity), Josef Seifert (spiritual substance in the body), Conrad-Martius (hypokeimenal pneumatic being), and Spaemann (no potential persons). The basal relations show: this concept of person leads to bR2 — all human beings are persons.
Three positive arguments sustain this concept of person. The argument Nature as Ground — sharpened in Spaemann’s formula “there are no potential persons” and deepened ontologically by Josef Seifert — shows that the ground of personhood lies in the rational nature of the bearer and not in the actual exercise of personal acts: whoever has the nature is a person, regardless of whether the faculties are already, still, or at all actualized. The argument from archphenomenal being-in-itself shows that the person is not a derived mark but a archphenomenon that shows itself and withdraws from every reductionist construction: whoever derives the person loses it. The argument from uniqueness — grounded by Richard of St. Victor in the formula persona est rationalis naturae individua existentia and by Spaemann in the present — shows that every person is an irreplaceable, unsubstitutable existence that cannot be offset against other persons. These three arguments together, supplemented by three objections against the empirical-functionalist concept of person — the Exclusion Objection and the Objection from Diachronic Identity (developed in the 2017 dissertation), as well as the performative contradiction (a further development of one’s own, Bexten 2026, following Apel’s transcendental pragmatics, closing a systematic gap in Spaemann) — form the dialectical scaffolding of the argumentation as it became a book.
Ontological classification: Broader term: Concept of Person; narrower term: Substance-Ontological-Relational Concept of Person
Chapter assignment: Chapter 3: What is a Person?
Sources: Generated by querying the Personhood ontology.
Further sources:
- Boethius: Contra Eutychen et Nestorium, ch. 3 (naturae rationalis individua substantia).
- Thomas Aquinas: Summa Theologiae I, q. 29, a. 3 (persona significat id quod est perfectissimum in tota natura).
- Conrad-Martius, Hedwig (1957): Das Sein. Munich: Kösel (hypokeimenal pneumatic being) (German).
- Seifert, Josef (1989): Das Leib-Seele-Problem und die gegenwärtige philosophische Diskussion. Darmstadt: Wissenschaftliche Buchgesellschaft (German).
- Spaemann, Robert, Persons: The Difference between ‘Someone’ and ‘Something’, transl. Oliver O’Donovan, Oxford University Press 2006.
See also
Nature as Ground, Archphenomenal Being-in-Itself, Uniqueness of the Person, Exclusion Objection, Objection from Diachronic Identity, Performative Contradiction, Richard of St. Victor, Person, Substance, Personhood, Person-Behavior, Agere sequitur esse, Empirical-Functionalist Concept of Person, Relational Concept of Person, Basal Relations, Human Person, Dignity, Someone, Form and Matter, Act and Potency, Body-Soul Unity, Metaphysics, Nature, Soul, Body, Essential Law, Archphenomenon, Personalist Norm, Cognition, Insight, Freedom, Love, Interiority, Reason, Self-Consciousness, Truth, First Dimension, Oblivion of the Person, Embryo, Dementia, Boethius, Thomas Aquinas, Robert Spaemann, Aristotle, Alexander of Hales, Josef Seifert, Hedwig Conrad-Martius, Berthold Wald, Chapter 3: Concept of Person, Chapter 4: Personhood