Aristotle, Categories. Chapter 8, Of Quality

Study Aristotle's Categories in the Classical Liberal Arts Academy

In this lesson, we continue our study of Aristotle’s ten Categories. Having studied Substance, Quantity and Relatives, we move on to Quality in chapter 8. Translation by Thomas Taylor 1. I denominate Quality that according to which certain things are said to be of such kinds. 4. But habit differs from disposition in this, that it is a thing more lasting and stable. And of this kind are the sciences and the virtues. For science appears to rank among the number of things which are more stable, and are with difficulty removed.   In like manner virtue, such as justice and … Continue

Porphyry, Introduction. Chapter 2

Study Porphyry's Introduction in the Classical Liberal Arts Academy

1. It seems that neither Genus nor Species is simply denominated. Of Genus 2. For a collection of certain things, subsisting in a certain respect with reference to one thing, and to each other, is called Genus; according to which signification the Genus of the Heraclidae is denominated from the habitude from one thing, I mean from Hercules, and the multitude of those who derive in a certain respect alliance from him; being Thus, denominated, according to abscission from other Genera. 3. After another manner also the principle of the Generation of everyone is again denominated Genus, whether from the … Continue

Free Book! Porphyry’s Introduction

Purchase a printed copy of Porphyry's Introduction from the CLAA Catalog.

We’re happy to provide Academy students with another newly published book: Porphyry’s Introduction to the Categories of Aristotle. This 3rd century classic is the first book studied in the Classical Liberal Arts Academy’s Classical Reasoning I course. You can download a free copy below, or purchase a printed copy from the Academy bookstore. God bless your studies,Mr. William C. Michael, HeadmasterClassical Liberal Arts

Aristotle, Categories. Chapter 3

Study Aristotle's Categories in the Classical Liberal Arts Academy

In this lesson, we study the third chapter of Aristotle’s Categories. Study the lesson for mastery, using the notes and comprehension questions as a guide. Translation by Thomas Taylor When one thing is predicated of another as of a subject, as many things as are spoken about that which is being predicated, can also be spoken about the subject.  Thus “man” may be predicated truly of an individual man (see line 1 below), and “animal” may be predicated truly of “man” (line 2); and therefore “animal” may also be predicated truly of that individual man (line 3).  For that individual … Continue

The Porphyrian Tree or Tree of Porphyry

The Porphyrian Tree or Tree of Porphyry

One of the most important (and difficult!) obstacles for students in classical Logic is understanding an illustration known as the “Porphyrian Tree” or the “Tree of Porphyry“. This illustration explains how Aristotle’s “Categories” are divided from the “genus most general” down through all subalternate genera and species, down to the “species most special” and individuals. It is the key to understanding Aristotle’s art of Reasoning, but it takes some work to understand rightly. Let’s take a careful look at the Porphyrian Tree above, and I’ll explain its meaning. Explanation of the Porphyrian Tree Starting at the top of the tree, … Continue

Poprhyry, Introduction. Chapter 3, Of Difference

Study Porphyry's Introduction in the Classical Liberal Arts Academy

Having studied Genus and Species, we move on to the study of Difference in chapter 3. Translation by Thomas Taylor Difference, however, is predicated (a) in common, (b) peculiarly, and (c) most peculiarly. 1. Simple Differences A. Common Difference (a) For one thing is said to differ from another in common, in consequence of differing in some respect or other, either from itself, or from something else. For Socrates differs from Plato, in being another person, and he differs from himself when a boy, and when he becomes a man, and when he does any thing, or ceases to do … Continue

Aristotle, Topics. Book I, Chapter 2

Aristotle Topics Book I Chapter 2

Translation Translation by Thomas Taylor To what has been said in chapter 1, it will be consequent to show in what the ability of this treatise consists, and how far its utility is extended. It is useful, therefore, to three things: to exercise, to common conversation, and to philosophic sciences. That it is useful indeed to exercise, is from these things evident; for possessing this method, we may be easily able to argue on every proposed subject. But it is useful to common conversation; because, when the opinions of the multitude are enumerated, we may converse with them not from … Continue

Aristotle, Topics. Book I, Chapter 1


Translation Translation by Thomas Taylor The design of this treatise is to discover a method by which we may be able to syllogize about every proposed problem from probable arguments; and so that we ourselves sustaining the controversy, may assert nothing repugnant. In the first place, therefore, let us show what a syllogism is, and what are the differences of it, in order that a dialectic syllogism may be assured; for we investigate this according to the proposed discussion. A syllogism, therefore, is a discourse in which, certain things being posited, something different from the things posited happens from necessity … Continue

Aristotle, On Interpretation, Chapter 3

Aristotle, On Interpretation

In this lesson, we study the third chapter of Aristotle’s treatise On Interpretation, the second book of the Organon. For tutorial resources on this lesson, please see the Academy YouTube channel. This lesson is studied in the Academy’s Classical Reasoning I course. The text below is adapted from Thomas Taylor’s translation of Aristotle’s Prior Analytics A Verb is that which in addition to something else signifies time; of which no part is significant; and it is always an indication of those things which are asserted of something else. But I say that “in addition to something else to something else … Continue