What are the fundamental teachings of Thomism?

Now, given what has been thought-through about Thomism and Thomists in the introductory posts, the next most obvious question is one related to the fundamental teachings of Aquinas and Thomism—what do Thomists more or less universally hold to be the case, or: 1) Are there particular teachings that are fundamental to Thomism? 2) In what sense might they be fundamental? 3) And what are they?

To answer the first, we must begin with the second: In what sense do I mean ‘fundamental’? By fundamental we should think of teachings that are both foundational and necessary, for all that is truly grounding (regardless of whether we are thinking of a building or a theory) is also necessary to everything subsequent in the superstructure. And by necessary, I here mean that its removal would lead to the undoing of the whole through the de-structuration of its unity.

With respect to Thomism, then, are there teachings that undergird the whole theoretical structure, in all its complexity, with all its parts? To this question, we can confidently say, ‘yes,’ without invoking any controversy. We could immediately here think of the concepts of act (actus) and potency (potentia); the real distinction of being (esse) and essence (essentia); the correlation of form (form) and matter (materia) in material being; the division of being into various modes of being (modus essendi) and predication (modus praedicandi); with a first division into the contrasted categories of substance (substantia) and accidents (accidentia); and, finally, the component that undergirds and embraces the whole theoretical framework, that of the analogy of being (analogia entis).

Each of these, and all together (since they are all interconnected), are surely foundational for Thomism, and all are mentioned in the introductory paragraphs of the ‘24 Thomistic Theses’—a set of teachings collated for and endorsed by the Catholic Church early in the 20th century. Though not an infallible pronouncement of the Catholic Magisterium, it certainly places emphasis on these particular teachings as worthy of close attention, and even if you are not a Catholic, given the attention of Catholicism to philosophy in general and Thomism in particular, it is worth taking note of this endorsement.

Let us here look briefly at each by approaching them from the coordinating perspective of the Thomistic understanding of being (esse), arguably the most foundational notion in Aquinas’ thought, and thereby reveal something of their foundationality as well as their closely interwoven character. Though we will cover each in greater detail in subsequent posts (as well as other foundational teachings), a short introduction will have to suffice here.

For Aquinas, ‘being (esse) is the actuality of all acts and, therefore, the perfection of all perfections’ (Summa theologiae I, 4.1, ad 3; among others). It is hard to imagine a more programmatic statement, and should we take it with due seriousness, we immediately see that everything is shot through with being, so that being is both first and last in all things. As such, it is the most basic of principle of Thomism since it affords the actualization of the whole of what we call reality (derived from the Latin for thing ‘res’), and here understood as the summation of all things in the harmoniously ordered whole of everything existent.

Simply speaking, being is the basis of everything we can say actually ‘is.’

Now, since ‘being’ here translates the Latin ‘esse,’ which is the infinitive form of the verb, it would be better (i.e., more literal) to translate it as ‘to be.’ Should we then return again to Aquinas’ programmatic statement, we see that he holds ‘to be’ itself to be the actuality of all acts and the most basic principle of his whole theoretical framework. Thus, for Aquinas, reality itself is nothing less than dynamic actuality.

‘To be or not to be,’ truly is the question.

Now, included within the domain of reality is both Creator and creation, precisely as similarly existent realities, even while the being of God and the being of creatures are radically different in each case. This differentiation is rooted in a closely corresponding teaching of Aquinas that ‘God is His own essence’ and ‘His own being’ (ST I, 3.4, co.), so that being and essence are actually coincident in the Creator, whereas everything created, because it is created, is necessarily a being-essence composite, so that being and essence are really distinct in every creature.

From this we can see that being and essence stand in an act-potency relation with respect to one another, where being is understood to be the principle of actuality (as a principle of ‘what is’), which actualizes its correlated potency, essence (as a principle of ‘what can be’), to produce a being-essence composite—an existent thing possessing unity of the highest kind (the act-potency unity).

Following Aristotle, Thomism calls these existent things ‘substances (substantiae),’ where substance is understood to identify a primary mode of being, because it has being in itself and thus ‘sub-stands’ all other modes of being. These other secondary modes of being are called ‘accidents (accidentia),’ because they have being in another for they require a foundation in substance to exist. There are nine accidents enumerated by Aquinas, following Aristotle, and they include quantity, quality, relation, action, passion, place, time, posture, and having.

With this basic description of reality already in place, Aquinas then proceeds to show that there is also another kind of act-potency correlation that is foundational to the world of material things. Unlike immaterial substances, which are being-essence composites alone, material substances are a further composition of form and matter, where form provides the principle of actuality and matter the principle of potentiality. (Thus, in an initial way, we see the basic agility of the universally applicable concepts of act and potency.) Then, for living material substances, the form is a special kind of form, a living form now called the soul (anima), where the soul is then understood to be the first principle of life and the form of the living material body. This is an incredibly significant Thomistic teaching that has foundational import for everything anthropological.

Now, above we noted that God and creature are radically different, since ‘to be God’ (here signifying the divine essence) is simply ‘to be’ (here signifying the divine actuality), whereas ‘to be a creature’ (here signifying the creaturely essence) is not simply ‘to be’ (here signifying the creaturely actuality). This means that while God exists by necessity, inasmuch as He possesses an received and unlimited act of being (actus essendi), creatures are radically dependent upon their Creator, inasmuch as they possess a received and limited act of being (actus essendi). This is a big difference.

Yet God and creatures are not so different that no similarity exists between them. After all, since creatures are made by God, they must be like Him in some or other way, for every effect is like its cause. This follows upon a basic metaphysical principle of Aquinas and Thomism, that all causes make, and can only make, effects that are in some way like themselves. Causes can give only what they have, and effects can receive only what the cause can give. For example, fire as an effect is like fire as a cause, and heat as an effect is like fire as a cause; even though in each case the effect is different, and more and less perfectly resembles its cause, both are nonetheless like their cause.

This then brings us right to the final teaching of Aquinas that I listed as foundational above, that of the analogy of being (analogia entis), which explains the Thomistic understanding of the way creatures are related and similar to God via their common possession of being. Having received being from their Creator, creatures are radically dependent upon Him for all they are and have; again, having received being from their Creator, creatures have a similarity to Him through their very participation in being, even though being is possessed by the creature as received and limited, while the Creator just is being by essence.

Therefore, this similarity to God through being also inaugurates the fundamental differentiation of God and creatures, in the still greater dissimilarity of creatures and Creator through the way being is differently possessed. Whereas creatures possess being in a dependent and finite way, the Creator possesses being in a self-dependent and infinite way—or rather, better stated, God just is ‘subsisting being itself (ipsum esse subsistens)’ (ST I, 4.2, co.; among others).

In accord with God’s possession of being by essence, and in correspondence to His universal causality, every true perfection found in created reality bespeaks of this same perfection in the Creator. Though these perfections—like unity, truth, goodness, beauty, nobility, justice, mercy, etc.—are found in creatures in received and limited ways, in God we must come to understand them as essential and infinite.

In just this way, the analogy of being reveals itself to be the Thomistic conceptual framework that embraces everything, both Creator and creature, in their relation and similarity, while simultaneously respecting their still greater distinction and dissimilarity.

This brings our summary of foundational Thomistic teachings to a close. We have here seen, even if only in outline and without demonstrative clarity, that there are certain foundational teachings so basic to Thomism that they are inextricably interwoven with his whole theoretical framework. Moreover, we can certainly grant that other teachings could have been included such that the listing here is not exhaustive. In later posts, we will look at each teaching by itself and with greater expansiveness, while also looking at many others, for much more reasoning is required to substantiate each of these, in themselves and in their relation to one another, or even just to understand them properly in a basic way.