1. The Ten Categories of Being
Aristotle 384 BC – 322 BC

2. Some Biographical Points
Student of Plato for 22 years at Plato’s Academy
Tutor of Alexander the Great
Systematized the science of logic. Wrote on the Philosophy of Nature, on the nature of poetry, politics, ethics, metaphysics, on the soul, biology, zoology, and more.

3. Some Biographical Points
Aristotle’s father, Nicomachus, was the personal physician to King Amyntas of Macedon.
Aristotle, thus, had a greater appreciation for matter, the physical, etc., than his teacher Plato. Because Plato argued that only forms or essences are true beings, and that forms exist in a separate intelligible World of Forms, and that this world is not fully real, he did not bother to study nature as much as he studied the nature of the state, law, politics, etc.

4. Plato reasoned that there is a world of forms separate from this sensible world, and in this world exists all the forms or essences. They exist in their pure intelligibility, as eternal and unchanging.
And so for Plato, the primary mode of being is “form” or “essences”.
This is not so for Aristotle. According to Aristotle, forms are in things, not in some separate world of ideas. And so the primary mode of being for Aristotle is “thing” or “entity”, or what he calls “substance”.

5. The Ten Categories of Being/Existence
For Aristotle, there are ten categories or modes of being, that is, ten ways to exist. The first way is primary, namely, substance. Things exist as substances (I.e., gold, iron, water, flower, apple tree, man, etc.)
The other nine ways are secondary. These modes of being “exist in” substance, and these are called ‘accidents’. (I.e., a desk, chair, paper, flour, sword, etc.)
Actuality vs. Potentiality

6. 1. Substance (principal mode of being/existing) ie Sammy the snake.

7. Accidents (secondary modes of being/existing).
2. Quantity: parts outside of parts…much
like numeric data…
continuous discrete
1, 2, 3, 4, etc.
No intervals or breaks in time…

8. 3. Quality: quality is a distinct mode of being than quantity
3. Quality: quality is a distinct mode of being than quantity. Asking ‘how much’ is not the same as asking about a thing’s quality.
affective qualities (colour, texture, etc)
abilities and disabilities (ability to grow, or walk)
Quality
habit and disposition (flammable, transparent, floatable)
form and figure (round, square, etc)

9. 4. The Relative (Relation): substances exist in relation to other substances. Beside, in front of, mother of, employer of, etc. What is a thing in relation too?
5. Where (place): Substances occupy place. Where is a different mode of being than ‘when’, or quantity. When we ask where something is, we are not asking about its relation, or size, or quality. Where does a thing exist?
6. When (time): Material substances exist in time. Time is not a substance but when is. If material substances did not exist, time would not exist. Time is the measure of movement according to a before and an after. Hence, time depends upon motion. When did it exist…When will it exist?

10. 7. Action: Substances can act in certain ways
7. Action: Substances can act in certain ways. Bird’s fly, dogs bark, trees produce, etc.
8. Passion (to undergo): Substances can be acted upon. I.e., getting forced into, rained on, etc.
9. Posture: Substances can take on a certain posture, I.e., sitting down, standing up, lying down.

11. 10. State (habit): clothed.
Accidents exist in a substance. They inhere in a substance. The word ‘accident’ is from the Latin ac-cidere: to inhere in.
The substance is that in which the accidents inhere. They actuate the substance in an accidental way, that is, in a way that does not change the substance itself.
The first accident quantifies a substance. A human being, for instance, was at one time smaller than your hand. He/she increased in quantity and is now six foot five inches, three hundred pounds. But even though his quantity changed, he/she (the substance) remained the same substance.
Quality qualifies a substance in an accidental way. You may change color after sitting in the sun, yet you are the same substance.

12. Note: If quantity = substance, then it follows that a change in quantity would amount to a change in substance. Bubba the Glutton would become a different substance the instant he gained any weight (after his body digested the dozen donuts he ate). But Bubba remains Bubba whether he loses or gains, whether there is more of him or less of him. It's still him.
Therefore: Quantity is distinct from substance (not separate). Quantity is a distinct mode of being (even though all substances have quantity).

14. Consider: The Medieval thinkers were able to use this doctrine of substance in order to show that what Catholics believe regarding the Eucharist is not irrational. They argued that it is indeed possible, if God so chooses to work the miracle, for the “substance” of Christ’s body to exist under the appearance of bread and wine.
Transubstantiation refers to the “changing of the substance of bread into the substance of Christ’s body; the changing of the substance of wine into the substance of Christ’s blood.
The substance of bread changes, while the accidents of the bread (quantity, color, taste, etc) remain the same. The substance of wine changes while the accidents of wine (quantity, color, taste, etc) remain the same.