Thomas Aquinas

1. Thomas Aquinas “On Being and Essence”

2. Saint Thomas Aquinas born ca. 1225; died 7 March 1274 Dominican

3. Existence as Superior to Essence Plato maintained that ultimate reality consists of essence. For Aristotle, existence is primary. For Plato, the world we perceive with our senses contains nothing except impermanent, ever-changing objects. Plato reasoned that for our observations of the world to count as true knowledge and not just as anecdotal evidence, our minds need to make a conceptual leap from individual instances of things to general ideas. He concluded that there must be something permanent that lies behind and unites individual existences, and he referred to this something as “essence.” According to Plato, existence, or the everyday world of objects such as tables, chairs, and dogs, is inherently inferior to essence. Early church thinkers saw in Plato’s ideas a parallel to their own division of the universe into the inherently imperfect, corrupt world of matter and everyday existence and the perfect and heavenly world of spirit.

4. Aquinas follows Aristotle in concluding that Plato’s theory is deficient, in part because it is unable to account for the origin of existence and in part because it is unacceptably dismissive of existence. Holy Scripture states that after each of the six days of Creation, God saw that the fruit of his day’s work was “good” or even “very good.” Furthermore, when Moses asks God how he should refer to him, God responds, “I am that I am,” thereby equating himself with being. In other words, God is pure existence or Being itself. Aquinas argues that man’s purpose consists exactly in developing himself toward Being, not in attempting to escape Being. In the traditional church view prior to Aquinas, the difference between God and his creatures was one of kind, as existence was something that in itself separated us from God. In Aquinas’s view, the difference between God and his creatures is one of degree, and we are separate from God insofar as we do not have as much existence as God. Prior to Aquinas, traditional church thought maintained that existence was the chief impediment to the realization of our spiritual destiny. Aquinas held that our spiritual destiny consists precisely in the enhancement of our existence. (SparkNotes)

5. Chapter 1 Aristotle says that Being has two senses: In one sense it signifies that which is divided into ten categories. In another sense that which signifies the truth of propositions. The difference is that in the second sense you can call anything being “about which an affirmative proposition can be formed” even if it posits nothing in reality. (In the sense, blindness, which is really just a privation, can be called a substance, it as a kind of being.) The term “essence” can only be associated with being in the first sense. (Think of the blindness example. Blindness can’t have an essence in that it posits something in the real world.) The term quiddity refers to a thing for what it is; philosophers introduce the term to mean the same thing as essence. It is what makes the thing what it is in relationship to other things; genus, species, etc.

6. Aristotle said that “every substance is a nature,” but Thomas Aquinas thinks that the term nature must signify “the essence of a thing as it is ordered to the proper operation of the thing, for no thing is without its proper operation.” But the “same thing is called essence, because the being has existence through it and in it.” Some substances are simple, and some are composite, and essence is in both. The simple substances are the causes of the composite ones, or “at least this is true with respect to the first simple substance, which is God.”

7. CHAPTER II In composite substances we find form and matter. It is clear that essence is that which is signified by the definition of the thing. The definition of a natural substance contains not only form but also matter (otherwise it would be like a mathematical definition). We can’t say that matter is added onto this natural substance as something added to or beyond the essence (that would be accidents, and they have a definition that goes beyond their own genus, which shows they don’t have a perfect essence). (I take this to mean that “white” or “heavy” are accidents, and do not have a perfect essence because they do not have a substance.)

8. Therefore, the essence clearly comprises both matter and form. Individuation emerges in such composite substances by way of signate matter. Signate matter is “matter considered under determinate dimensions.” Signate matter is not included in the definition of man as man, but it would be included in the definition of Socrates as Socrates (if he had a definition). This term body, therefore, can signify a certain thing that has a form such that from the form there follows in the thing designatability in three dimensions and nothing more, such that, in other words, from this form no further perfection follows, but if some other thing is superadded, it is beyond the signification of body thus understood.

9. CHAPTER V There are three ways in which substances may have an essence. First, is the way God has his essence, which is his very existence itself, and so we find certain philosophers saying that God does not have a quiddity or essence because his essences is not other than his existence. Even though we say that God is existence alone we do not fall into the error of those who said that God is that universal existence by which everything formally exists. The existence which is God is of such a kind that no addition can be made to it. When through its purity it is distinct from every other existence. Similarly, though God is existence alone, the remaining perfection and nobilities are not lacking in him. (In fact, he has these perfections in a “more excellent way.”) Second, essence is found in created intellectual substances.

10. (That material objects, for Aristotle and Aquinas, are contingent. This problem of contingency is what he wants to explore in his second mode of essence.) In this second mode, existence is other than essence, even though in these substance, it is essence without matter. Third, substances composed of matter and form in which existence is both received and limited because such substances have existence from another, and again because the nature or quiddity of such substances is received in signate matter.