The argument from uniqueness is one of the most deeply anchored arguments for the substance-ontological concept of person. It runs: the person is not a specimen of a species, but a unique, irreplaceable entity that cannot be substituted. A person is someone and not something — and as this someone, the person exists only once.
Richard of St. Victor supplemented the classical medieval definition of the person with precisely this element. Boethius had defined the person as naturae rationalis individua substantia — as a unique, self-subsisting being with a rational nature. Richard adds: persona est rationalis naturae individua existentia — the person is the unique existence of a rational nature. The accent falls on existentia, on the unique act of being-there. Every person is a unique bringing-forth into being, not merely one further occurrence of a kind.
Robert Spaemann translated this argument into the present. He opens his book Persons with the observation that we do not count persons as we count things. Two identical chairs are two chairs; two identical persons would be a contradiction in terms. Even identical twins are two persons, because they are two unique existences, not two specimens of the same individual. Uniqueness is not a statistical statement about rare properties, but an ontological statement about the very mode of being of the person.
A series of consequences follows from this. First: persons cannot be replaced. The loss of a person cannot be compensated for by another person, not even by a similar one or by one comparable in every respect. Second: persons cannot be weighed against one another. The utilitarian thought that many human beings might have a higher value than few, and that a sacrifice might pay off, misses the ontological structure of the person. Third: the dignity of the person has its ground in its uniqueness. Dignity is neither gradual nor comparative, because that which bears it is incomparable.
The argument is closely connected with the argument Nature as Ground and with the primordial in-itself-being. All three arguments together sustain the concept of person that the dissertation defends as adequate.
In the Argument Map of the Concept of Person: Appears as the syllogism Person as intellectualis naturae incommunicabilis existentia of Richard of St. Victor and stands in the line Boethius → Richard → Wojtyła (personalist norm).
Ontological classification: Superordinate concept: Argument; supports: Substance-Ontological Concept of Person
Chapter assignment: Chapter 3: What is a Person?
Sources: Generated by querying the Personhood ontology.
Further sources:
- Richard of St. Victor: De Trinitate IV, 22 (persona est rationalis naturae individua existentia).
- Spaemann, Robert: Persons. The Difference between ‘Someone’ and ‘Something’. Translated by Oliver O’Donovan. Oxford: Oxford University Press, 2006.
- Boethius: Contra Eutychen et Nestorium, cap. 3.
See also
Substance-Ontological Concept of Person, Someone, Dignity, Nature as Ground, Primordial In-Itself-Being, Richard of St. Victor, Robert Spaemann, Boethius, Chapter 3: Concept of Person