This is a summary of some key concepts for the understanding of the Thomistic theological constructs for the structure of reality and being.
In Aristotle, there are two senses of substance: the “first substance” is a whole, concrete entity – this horse, this man. The second sense, or “second substance” refers to quiddity – horse, man.
First substance refers to a being or an entity subsisting or existing in itself, not in another being like an accident. This is a metaphysical category; e.g., God, angels, human beings.—not physical, chemical substance. It is the basic ontological unit, a complete, individual whole, a determinate, particular subject of existing and acting, e.g., this tree, this human being, Tom, Mary, etc. It is the proper subject of existence, “that which exists [quod est],” not “that by which something exists [quo est]”
This is the first “category” of Aristotle’s ten categories or predicaments, the principal and primary sense of being. (See the list below)
Aquinas defines “person” as “individual substance of rational nature,” (cf. Boethius) and divine persons as “subsisting relations.”
Second substance refers to the essence/quiddity/nature (including both substantial form and prime matter) that defines the kind of being something is, “that by which” a thing remains the kind of being it is; it is universal, not particular like first substances, and is realized only in first substances. Iit is an internal principle of being (not a being), “that by which”; e.g., humanity, dogness, treeness, not a human being, a dog, a tree—entities are not all externally determined but have certain natures intrinsic to themselves that make them what they are and make them act as what they are; intrinsic or internal principle of being and acting.
Therefore it refers to a set of the defining potentialities proper to a specific kind of being to be actualized by accidents; it provides identity, continuity, and stability in the midst of “accidental changes,” coming to an end when “substantial change” occurs and the entity ceases to be what it is – for example when a body ceases to be human by dying and being decomposed in to chemical substances.
They refer to realities that cannot exist in themselves, like first substances, but only in something else that does exist in itself – like color, weight, action, passion, etc. Iit is that by which a being can change while remaining the specifically and individually same entity and provides the elements of change and difference; it is the principle of diversity within the unity of the first substance. Some accidents are called “proper” accidents because they are proper to the species as a whole (e.g., ability to speak, laugh)
There are, according to Aristotle and Aquinas, nine categories of accidents, or modes of being in which a first substance can exist
- Quality: good, bad, wise, white
- Quantity: two feet long
- Action: run, walk, etc.
- Passion: being burned, being cut
- Relation: double, half, greater than
- Place: in the classroom, in Claremont, etc.
- Time: yesterday, last year, etc.
- Posture: reclining at table, sitting down, etc.
- State: having shoes on, being in armor
Structure or Essence of Material Substances:
The essence of material substances is composed of substantial form and prime matter. Substantial form is the source of the specific identity or identity as a species, as a human being, as a dog, etc. Prime matter is pure potentiality to be specified, determined, activated by the form. It is the principle of individuation: it multiplies the form and accounts for diversity within the unity of the form or species by receiving and restricting the form to “this” material subject–the possibilities of the species are not exhausted by an individual. For example, “humanity”is multiplied into “many human individuals” by matter.
Consequently, in human beings there is a composite of form and matter: hylomorphism. There is a unity and distinction of soul and body – soul as form of the body (matter); the soul is the efficient, transcendent cause of the body through intellect and will
Ultimate Principles of Being: Essence and Existence
For any being, or substance there are two fundamental questions: what something is and whether it exists—essence and existence
As such, there is a distinction between ens (a being), esse (to be, act of being, act of existing, activity of existing, existence, as verbal noun), and essence– the act of existing diversified by a diversity of essences. For example, one can ask whether a unicorn actually exists.
There is real distinction between essence and act of existing in all finite beings – they may or may not exist – but only a rational distinction in God, since God’s essence does not possess existence, but rather, is identical with his existence.
Ontological primacy of esse, existence:
Thomism is a metaphysics of existence, not metaphysics of first substance–esse is not to be reduced to substance. It is an existentialist, not essentialist ontology. The general rule is that the actual determines the potential (e.g., accidents determine substance; form determines matter (specifying and actualizing).
The act of being cannot be determined by anything outside itself, i.e., by something not existing. It can only be determined internally from within – the finite act of being is not absolute, pure, unique esse but only an act of being of a certain limited kind.
This limitation can only come from essence, which as potency, potentiality of certain kind of being, receives, determines, specifies, and limits the act of being. Thus, the act of existing both actualizes the essence as something other than itself and is limited by essence.
This is different – even opposite than previous ideas found in Alfarabi, Avicenna, Algazali, which, in making a distinction between essence and existence, considered existence as added to essence, i.e., existence as accident, which is then an essentialist philosophy (not existentialist).
In contrast, for Aquinas, existence is not on same level as essence. Existence is not another accident, but the most intimate and most profound element in all things. Existence as accident cannot explain the necessary existence or simplicity of existence in God. Esse and essence belong to two different orders altogether: esse transcends the whole plane of essence.
Essence is distinct from existence and essence does not contain existence but is also thoroughly actuated by existence. Existence is internal to essence in the sense that essence is truly essence only when actualized by existence, but essence is external to existence in the sense that existence is not inherent in essence; that is to say, a thing can be or not, exist or not; to be a particular kind of being is not necessarily to exist as that kind of being—existence is most internal to me yet external to my essence as this individual of a particular kind.
To create is precisely to produce the esse of things – it is to make things exist. The creator is most intimately present to things because he is present to their act of existing—more deeply than to their materiality or even their spirituality. God is more intimately present to me than I am to myself – as Augustine said, intimius intimo meo.
Existence is graced, intrinsic to me as most intimate to me yet not constitutive of me because I am not my own existence—my existence is always borrowed, gifted, given. Existence is not part of my essence. This distinction precludes pantheism, and yet it does involve a certain panentheism: all things are in God, in the sustaining power of God’s creative causality.
All things have meaning only in relation to existence; what is most perfect is the act of existing, related to all things as to their first act. Existence is the actuality of all things, including essence, form, matter, etc. It precedes all other perfections: the good, the beautiful, one, etc.; these latter are meaningful only insofar as they are or exist and therefore only as particular modes of being or existing. There is a primacy of existence in Aquinas vs. the primacy of the Good in Plato.
Cognitive primacy of existence:
Esse, existence, is the horizon of all cognition: all things are understood as existing or at least as capable of existing (the first principle) and we perceive all things under the horizon of being (sub ratione entis). The natural tendency of reason is to essentialize existence, turn it into a mode or kind of essence, especially material essence—to reify esse into a frozen essence, to reduce existence to an abstract concept.
We must distinguish between simple apprehension of essence or quiddity (first operation of the intellect, i.e., what is this? It is a horse, or a unicorn.) and the act of judgment which composes or combines or separates essence and existence (second operation of the intellect which regards the esse of things – the unicorn does not exist, the horse exists). Thus, there is a judgment of existence: “Socrates is”– a composition of substance Socrates and its existence in the unqualified or absolute sense.
It depends also on what the meaning of “is” is!
Judgment of existence in the qualified sense would be: “Socrates is a human being” – the role of the copula: essence of Socrates is to be a man, or white–existential value is not direct in the copula, but still there–actuality of the act of existing is the principal signification of “is,” but secondarily all actuality whatsoever including the actuality of a certain form (man, white).
The copula still designates composition of form and existence; the actuality of the form is consignified —“Socrates exists with such and such determinations” still specifies his particular mode of existing. The unity of subject and predicate is affirmed as existing in reality, outside the mind, irreducible to our own affirming subjectivity. Thus the modern turn to the subject has its limitations.
Every time we make such judgments – Socrates is … – we are already affirming existence, and act of existing as grasped in the act of judging contains a permanent reference to an infinitely rich reality of the pure act of existing–pursuing it all the way to the supreme existent, God. As concept, being is most universal and most abstract—richest in extension but poorest in comprehension. Reason dislikes the undefinable, which being is in its inexhaustible reality.
Real distinction between essence and existence in finite beings
Essence can be understood without knowledge of its existence. There is a radical contingency of all beings (they may or not come into existence, and they may nor not cease to exist) and there is the impossibility of there being more than one being in which essence and existence are identical (God).
Existence and essence are related as act and potency. There is no potency in God, who is pure actuality because his essence is identical with his existence.
God is not a genus, a quiddity. Finite existence is existence by participation; God exists by essence – ipsum esse subsistens, the very act of existing that subsists, the subsisting act of existing
Kant says that existence is a logical, not a real predicate, but this is not true; existence is neither merely logical nor merely one among other predicates, but the predicate that confers reality on all other predicates because existence makes all predicates real. The reality of predicates depends on existence.
Thus, Thomist theology is a theology of being (sapiential, contemplative), as opposed to contemporary theologies of life, existence, praxis, liberation, hope, etc. (prophetic, practical).
Kierkegaard speaks of forgetfulness of existence in the subjective sense, Heidegger of forgetfulness of being—Aquinas speaks of the forgetfulness of existence in the metaphysical sense—the sense of the suppression of contingency of existence, death, old age—our tendency to reduce reality to the sensible in their particularity—and ignore the act of existing as the most profound and intimate act of a being as a being (shich requires contemplative detachment from the lures and illusions of sensible things)
Because of the composition of act and potency, where every act is the actualization of an existing potentiality, the world is not a mere succession of purely contingent appearances or acts but an orderly succession of intelligible, stable events—there is no act which is just act without actualizing a potentiality, while potentiality, if it is real, is an already actualized potentiality.