Aristotle's Categories are taken from a section of his work on logic, Organon, entitled Categories. The works of Aristotle, a philosopher of Ancient Greece, were extremely influential on the development of Western philosophy and science for centuries after he lived. Aristotle's Categories deal with the nature of any given part of a proposition, a statement that can be proven either true or false. Therefore, Aristotle's Categories are an integral part of the study of Aristotelian logic.
Aristotle's Categories are ten in number and can be used to identify both the subject and the predicate of a proposition. The predicate is that which can be proven true or false about the subject. In the sentence "All men are mortal," for example, "All men" is the subject and "are mortal" is the predicate.
The first of Aristotle's Categories is Substance. This is both the most complex and the most controversial of the Categories. Put simply, substance is that which exists in and of itself. All of the other categories say something about the substance, but the substance itself can stand alone. Some modern philosophy rejects this definition of substance.
The second of Aristotle's Categories is Quantity. This refers to the physical size of something and is the basis for much later mathematical thought. Nearly any concept that is physical in nature and can be measured in numbers would fall into the quantity category, such as descriptions of height, weight, and width.
Aristotle's third category is Quality. This describes the inherent nature of an object. Quality also includes physical descriptions, but only those that cannot be described mathematically.
The fourth of Aristotle's Categories is Relation, which describes how one object relates to another. The relation of one thing to another may be that of cause and effect, or that of equivalence, for example. Things can also be related physically, such as one being smaller than the other, or temporally, such as one being earlier than the other.
Aristotle's fifth category is Place. This refers to the object's physical position in the environment, or its location. The sixth is Time, or the object's temporal position, either in relation to certain events or in relation to any timekeeping system.
The seventh of Aristotle's Categories is Position. This refers specifically to the position of different parts of the object in relation to each other, and may be better understood by some as "pose" or "posture." The eighth is State. This is an ongoing but not an inherent attribute of the object. Whereas an adjective like "light-hearted" may fall into the quality category, one like "sleeping" would be classified as a state.
Aristotle's ninth category is Action, referring to how changes to an object affects something else. Conversely, the tenth category is Passion or Affection, regarding the changes that something else has on the object.
Every part of a verifiable statement, or proposition, falls into one, and only one, of these categories, according to Aristotle. Here is an example sentence with the pertinent categories in parentheses: The shy (quality), five-foot-two (quantity) girl (substance) reclined (position) beside her sister (relation) in her backyard (place) that afternoon (time), pleased (affection) with the strawberries she ate (action), but bored (state).