Subsistent being
| Category | Philosophy |
|---|---|
| Depth | Standard |
| Article type | local Catholic reference article |
Definition
Subsistent being, in the Thomistic expression ipsum esse subsistens, means existence itself subsisting rather than existence received in a limited creature. Aquinas applies this to God. He does not mean an abstract concept floating somewhere or the sum of all things. He means a real source whose existence is not dependent in the way creaturely existence is.
Catholic usage
A creature has a definite nature and actually exists. On Aquinas's account, what it is does not make it the complete explanation of its existing. God, by contrast, is not composed of a nature and an act of existence received from another. Divine essence and existence are identical.
This language is difficult because we first know limited things. We usually distinguish a subject from what it possesses: a person has knowledge and life. In speaking about God, Aquinas denies that these perfections are additions to an underlying, incomplete subject.
Doctrinal context
Why introduce this account? If the ultimate source received existence through a distinction requiring actualisation, it would still stand in need of an explanation beyond itself. The explanatory inquiry would not have reached an ultimate source. Aquinas therefore argues that the first cause cannot have the creaturely composition of essence and existence.
This does not make an abstract universal creative. The general concept “existence” is in the mind; it neither builds houses nor causes creatures. Subsistent being names the proposed actual cause, not the concept by which we speak about it. Confusing these is a serious error in explaining the argument.
Nor does the doctrine make creatures parts of God. A finite being has its own created reality while depending wholly on its cause. Causal dependence differs from being a piece of the cause's substance. Creation is therefore distinct from pantheism.
Distinctions and safeguards
The claim belongs to Aquinas's metaphysical explanation of divine simplicity. Its truth depends on the reasoning about existence and dependence, not on agreement to use a definition. Likewise, saying that God is beyond a creaturely genus does not mean that nothing true can be said of him; analogical language provides another way of speaking.
How can this be a living God rather than an impersonal abstraction?
The expression answers a question about existence and dependence. Further arguments address intellect and will. An explanation becomes misleading if it either identifies subsistent being with a mere idea or assumes that the word alone proves personal knowledge and love. In Christian theology these philosophical conclusions are also distinguished from the revealed doctrine of the three divine Persons.