Introduction
This lecture is intended for students enrolled in the Academy’s Classical Reasoning One course. If you’re not enrolled and would like to join us for self-paced studies, visit classicalliberalarts.com. My name is William Michael. I’m the Academy headmaster, and I’ll be leading this study of chapter one of Porphyry’s Introduction.
We’re studying chapter one, as I said, of the Introduction of Porphyry. Porphyry, who lived in the great ancient city of Tyre, was a Greek philosopher who lived from around 234 to 305 AD, 234 to 305 AD, so we’re talking Christian Era. He wrote this work, this Introduction, around 268 AD, around 270, and he was a student of the great Platonic philosopher Plotinus. This Introduction from Porphyry, which is also referred to as the Isagoge, which is just the Greek word for introduction, was written to help students understand the basic terms, the basic concepts that were said to be needed to study Aristotle’s Categories, which is, of course, one of the most important works in logic and philosophy, a work that many students stumble upon when they attempt to study it, and it leads many to quit the study of philosophy.
This opening chapter in Porphyry’s Introduction serves as his statement of purpose. He explains what he’s going to teach and what he will also avoid discussing in order to keep this treatise, which remember, is an introduction, simple and practical. This Introduction, Porphyry’s Introduction, became one of the most influential texts in medieval education, and was considered essential reading for all students of philosophy in Catholic universities, and certainly helped to shape how the church’s greatest thinkers, like St. Thomas Aquinas, approached the study of Aristotelian logic. If you find old copies of Aristotle’s Organon, his works on reasoning, you’ll almost always find Porphyry’s Introduction included in the work as almost a part of the study.
The text of chapter one can be read on the Academy website, and I’m going to avoid reading the text here, because it’s too long to include in a lecture, but you can read the text, and you should read the text before moving forward with the lecture. So if you haven’t read the text yet, hit pause, go read it and then come back and pick up where you’ve left off.
Division
We’d like to divide the text, identify the parts, the significant parts of this first lesson, and we can do that pretty easily. The first part consists of Porphyry’s statement of purpose. This begins right at the top of the chapter. He says, “Since it is necessary both to the doctrine of the categories of Aristotle…” and so on. He explains why the knowledge of the five predicables, as they’re called, and we’ll get into them in detail as we go through this book. Why this knowledge of the five predicables is necessary for studying Aristotle’s Categories, as well as for the work of making definitions, divisions in logic, and demonstration or proof. So he states his purpose. That’s the first part of this lesson.
Secondly, he discusses his method, his methodological approach to this study. This part begins where he says, “In a summary way I will briefly endeavor to discuss…” and so on. So Porphyry explains how he’s going to go about presenting this introduction to us for study.
Part three, he talks about the limits of this study, and the fact that this could actually become a very complex, a very profound study, but he’s not going to allow it to do so, because it’s intended to be an introduction. This third part begins where he says, “My meaning is that I shall omit to speak about genera and species.” He limits the content of this work. He says that these are deep metaphysical questions, and he’s not going to address that sort of content in this work, but keep things simple and stick only to the purpose that he’s intending, and that’s a good lesson for us anytime we write or speak, to have that prudence and patience we see in Porphyry, to not try to do everything. Every time we write something, or every time we teach a lesson, there’s a proper place and a proper time for different content and levels of content. And we have a good example here in Porphyry of how a good teacher works, making good use of time and opportunity.
And then lastly, part four, he talks about the positive plan for this study. We find this part where he writes, “In what manner, however, the ancients, and especially the peripatetics…” In what manner begins part four. He promises to show how the ancient philosophers and most importantly, Aristotle’s followers, the peripatetics, discussed these matters that he’s going to set out in this introduction.
So the basic idea of this work is that Aristotle’s Categories can be very difficult to understand if you don’t have a preexisting understanding of five important terms, and these are called the five predicables, which we’ll look at in detail in just a minute as we get into the exposition, but also as we study through this entire book. That’s the topic of this whole book.
So we have the four parts of this lesson: the statement of purpose, the methodological approach, the limitations of the work, and the positive plan for this work.
Interpretation
So now let’s go ahead and work through the text in detail. We’ll go through each line and make sure that everything is crystal clear. Porphyry writes at the beginning of the chapter, “Since it is necessary both to the doctrine of the categories of Aristotle and to the formation of definitions, and in short, to those things which pertain to division and demonstration to know what genus and difference, species, peculiarity and accident are, and since also the theory of these is useful.” And there you heard me mention the five predicables, these five important concepts that need to be understood: genus, difference, species, peculiarity and accident. These are the five predicables, really the subject of this introduction.
Porphyry explains the practical necessity of this work. He says it’s necessary, and he means that students can’t properly understand Aristotle’s Categories without first learning about the five predicables. And this is something I talk about with my students all the time. I say you’ve got to realize that when Aristotle was writing in 350 BC, his audience had a knowledge of certain ideas, things taught by philosophers like Pythagoras and Socrates and Plato, and those ideas that his audience already possessed are not present in the minds of modern students. So even in the time of Porphyry, it was important to introduce students to the basic concepts that were needed as prerequisites for the study of Aristotle’s Categories.
The Categories is Aristotle’s work that explains how we organize the different ways that we speak about things. The word “categories” actually comes from the Greek word for predicates. So if you think of what a predicate is in English, it’s what we say about a subject. The word for predicates in Greek, if we translate it into English, is category. It literally means a predicate. So the first work in Aristotle’s Organon is called the Categories, or the study of the predicates, things that can be said about subjects. Aristotle explains all the different ways that we can speak about things or predicate about things, subjects, whether we’re talking about what something is, how large it is, where it is, and so on. But before students can understand the complex system that Aristotle develops, they need to understand these five basic terms that Aristotle is going to use throughout that work. And again, the five terms are genus, difference, species, peculiarity and accident.
He says that this is necessary, not just for the study of Aristotle’s Categories, but also for the formation of definitions. For the formation of definitions, and often we think of definitions being found in a dictionary, but we don’t think about what a definition actually is. Most of the time, when we talk about things or give the meanings of words, we’re merely describing those things, we’re not actually defining them. The formation of definitions is actually very difficult. It requires a great deal of wisdom. Really can only be done by philosophers, and so Porphyry says, because this work of forming definitions is central to the work of philosophy, we’ve got to learn how to form definitions, and in order to do that, we need to understand these five predicables.
So the formation of definitions that Porphyry refers to refers to the logical process of saying exactly what something is. And again, it’s not as easy as it seems, saying exactly what something is. I used to do a little activity with my classroom students on this topic, where I would name something very common, very simple, like a cat or a squirrel, and I would ask the students to take a minute and write the definition of that object, whatever it was, write the definition of that object on a piece of paper, and they’d all sort of giggle and get started. And then after a few seconds, they would realize that they couldn’t do it. They didn’t know how to form a definition. They might put together, like I said, a description, but we would quickly see that that description that they gave didn’t identify that one animal or object alone, but could be applied to many different animals. And so to really identify the essence of a thing, what it really is, and communicate that, it’s very easy to show students that that’s very difficult to do.
So this process by which we say exactly what something is actually requires a great deal of learning, great deal of wisdom. For example, when we define man, if we ask, what is man? The answer is, man is a rational animal. And what we’re doing there is we’re identifying two important pieces of information when we define something. The first thing that we do is identify its genus. We say that man is an animal. He belongs to the genus animal. So the first part of a definition is the identification of the genus. And then the second thing we do is identify the difference, the specific difference. And again, don’t worry if these terms are unfamiliar. This is what we’re going to be studying in this book. We need to identify the genus of a thing and the difference that is what causes it to differ from all other things in that genus. When we define man, we identify his genus, we say he’s an animal, and then we identify his difference. What makes him different from all other members of that class. He is rational. Man is a rational animal, that’s the definition of man.
So you can see that we’ve got to already know what the different genera, that’s the plural for genus. We’ve got to know what the different classes of things are, and we’ve got to understand what it is that actually divides those classes into their different species. So it takes a great deal of philosophical knowledge in order to define things as simple as that may seem.
So he says, we’re studying these five predicables in order to understand Aristotle’s Categories, in order to form definitions. And then he says, in order to make divisions in philosophy, what does he mean by division? This means breaking down general categories into their specific parts. If you want to understand this quickly at this point, you might just want to Google the phrase “tree of Porphyry.” Tree T-R-E-E of Porphyry, and you’ll see illustrations from the Middle Ages, usually that show the division of a class of things into all of its different species, from the most general genus all the way at the top down to individual things like Socrates and Plato, individual men. So this work of dividing these different genera into their species, and continuing to do that all the way down to the individual beings contained in these classes. That’s the work of division. Again, another very important task in philosophy, but very difficult.
So division means breaking these classes down into their species, or specific parts, like dividing animal into rational animals and irrational animals. That would be an example of division, and we’ve got to make this division truly, it’s got to be the right division. So that’s what makes it difficult. What exactly are the principles of these divisions of things? That’s this work that Porphyry says we can’t do unless we understand these five predicables.
And then lastly, the last purpose he mentions is demonstration. It’s necessary for demonstration. And demonstration means to prove something, to actually use a syllogistic or demonstrative proof. We’re going again to have to understand the five predicables, genus, difference, species, peculiarity and accident.
So that’s the purpose, that’s the goal of this study, to give us a knowledge of the five predicables so that we can become skillful in these important studies and tasks in philosophy. He says that the five predicables are the basic tools for all of this logical work, and remember that logic is one of the branches of philosophy. It’s rational philosophy. In order to study and progress in rational philosophy or logic, we’re going to have to understand these five predicables.
The first is genus, which is a general class. The word “general” actually comes from the word genus. It refers to a class of things, a genus. We then ask how a genus divides into species, which are classes contained within a genus, the actual natural divisions of a genus into its different kinds. And a difference is that characteristic, which is the cause of that division. We used an example before we said, that animal, the genus, divides into rational and irrational, and rational animal produces the species man, irrational would produce the species beast. So we see how a genus or class divides, and difference is one kind of characteristic of a thing, that which actually causes the genus to be divided into different species.
The fourth of the predicables is peculiarity. A peculiarity is a characteristic of a thing that’s unique to that thing, unique to that class. So there’s a subtle difference between difference and peculiarity. Peculiarity is something that is unique to a class of things. But it’s not that which divides the genus into species. And the example that Aristotle gives would be the neighing of a horse. The horse is the only animal that neighs. Therefore, neighing is a peculiarity. It’s not that which divides the genus into its species. It’s simply a characteristic which is unique to one class of animals. So that’s a peculiarity. Peculiarity of man, for another example, might be that man laughs. Man is the only animal that laughs. That is a peculiarity of man, a peculiar characteristic of man. But it’s not the defining or the specific difference that separates men from other animals, but it is peculiar to men.
And then lastly, accidents. Accidents are qualities that may or may not be present in a thing. So, for example, a man may be tall or short, the characteristic tall is neither a difference that divides a genus into species, nor is it a peculiarity, because many different things can be tall, but it is something that can be predicated truly of man or of any other subject. So that’s an accident, something that may be true or false, or present or not present with a thing.
So these are the five predicables, genus, difference, species, peculiarity and accident. Porphyry, again, says that the knowledge or the theory of these predicables is useful to us, because mastering these concepts gives students the foundation, an understanding of the most important ideas that are needed to advance in logical thinking, in the study of rational philosophy, so we have a good sense of what needs to be studied and why it needs to be studied. Another example of Porphyry’s ability to teach well, to not only explain what is to be done, but to explain why it needs to be done to motivate us to study.
He goes on to say, quote, “In a summary way, I will briefly endeavor to discuss for you, in the form, as it were, of an introduction, what has been delivered on this subject by the ancients, abstaining from more profound investigations, but appropriately directing my attention to such as are more simple.” So again, he limits the content of this introduction. He says that he’s going to present this information not in a detailed study, but in a summary way. He says that he will briefly endeavor to discuss the subject in the form, as it were, of an introduction. So he explains the teaching method that he’s going to follow in this work. He’s going to give a summary treatment. He’ll cover the essential points, what needs to be known by students at this point in their studies without showing off or getting lost in every detail. He says, “as it were, of an introduction” to give some humility to this work that he’s doing. He knows that this is just the beginning, and he doesn’t take the opportunity to show off or talk about lofty things. He says, No, that’s not appropriate for teaching. He says, This isn’t the final word on these topics. It’s just an introduction, and I’m going to share with you the essential things that you need to learn at this point in your studies.
He then mentions, very importantly, that he’s going to share in this introduction what has been delivered on this subject by the ancients. And this is important, because we often make mistakes in modern society when we talk about these things. Because we’ve got to realize that when Aristotle wrote in 350 BC, much of what we know of today and take for granted was not known to Aristotle for good and for evil. There are many things that we know that Aristotle didn’t know, like the Christian faith and Scholastic philosophy, that would have been very helpful to Aristotle, but they weren’t known at that time, and we’ve got to be very careful that we don’t read ideas that developed after Aristotle back into Aristotle’s writings. There are also many things that we get wrong, and we can’t read back our errors, common faults and ideas of modern society that would not have been accepted to Aristotle or his audience. We have to be careful not to read these ideas back into Aristotle’s teaching when we study Aristotle.
So in order for us to understand Aristotle’s teachings, we have to be very careful to understand Aristotle’s words and ideas as he originally intended them to be understood. And in order to do that, if we ask, well, how can we do that? How can we learn what Aristotle actually meant by the different words or ideas that he discussed in his writings? And the answer is, we can go back to ancient followers of Aristotle, and we can see how men who studied under Aristotle spoke and wrote about those ideas. So we can draw this information, this helpful information, we can draw it from the writings of the ancient followers of Aristotle, who are called the peripatetics. That’s the name of the school of philosophy to which Aristotle’s followers belonged, peripatetics.
So Porphyry explains not only what we’re going to study, not only why we’re going to study it, but where we’re going to get our information from. And then he talks about what we’re not going to do. He says we’re going to avoid more profound investigations, deeper, more complex questions and topics. We’re going to focus on what is simple and necessary. And this, again, is another good example that Porphyry provides us with as we see him teaching. He’s teaching us how to teach. Don’t get into the complex stuff in the beginning. There’s a proper time and place for everything.
So he recognizes that beginning students need to master the basics before they can handle the most difficult questions. He also respects Aristotle as the teacher in the same way that John the Baptist did in the New Testament. When John the Baptist comes, he comes to prepare the Jewish people for the coming of Christ. And he recognizes himself as the forerunner to Christ, and he’s drawing attention to Christ, not to himself, sharing with the people what’s necessary to prepare them for the coming of Christ, telling them to get ready to be baptized, to repent of their sins and so on, to bring forth fruits worthy of repentance, to get ready because the Christ is about to be revealed in their time. So you can see that humility of the teacher who leads students to the masters, helps them to understand the masters, but doesn’t put himself in the way of those masters. I try to imitate that method of teaching in everything I do in the Classical Liberal Arts Academy.
So again, Porphyry recognizes that students need to master the basics before they can get into any deeper philosophical questions. He follows the principle that learning needs to proceed one step at a time from what is easy for us to understand, especially when we’re beginning, towards what is more difficult and more profound, that there’s an appropriate time and place for everything that takes discipline in teachers. And again, Porphyry gives us a good example of how to teach well.
He goes on to say, “My meaning is that I shall omit to speak about genera and species, whether they have a subsistence in the nature of things or have an existence alone in the mere conceptions of the soul. If they have a subsistence in the nature of things, whether they are bodies or incorporeal, and whether they are separate from sensible things or in sensible things. And about these have their subsistence, a discussion of this kind is most profound and requires another greater investigation.”
So he explains exactly the kinds of questions that he’s not going to get into in this study. We see here Porphyry’s philosophical wisdom. We see that he is aware of the deeper metaphysical questions that relate to these issues, but he is going to intentionally avoid them. The first question he mentions was whether genera and species have a subsistence in the nature of things, or have an existence alone in the mere conceptions of the soul, obviously heavy philosophical language. What he’s asking is whether these concepts, genera and species, exist in reality outside of our minds, or whether they are only ideas in our thinking. So for example, the idea of animal, the class of animal, it’s a metaphysical question, not appropriate for logic class. It’s a metaphysical question whether animal actually exists outside of our mind, or whether that name and the idea that it represents, the class that it represents is simply a word that men have invented and defined and use. Is there really something called animal, or is that just a name that man has given to what appears to be a class of living things? That’s a metaphysical question that is not appropriate for a reasoning class.
This is known in philosophy as the problem of universals, and as we’ll find when we go through the history of philosophy, this turned out to be one of the greatest controversies, one of the greatest debates in medieval philosophy. So Porphyry is aware of the controversies. He’s aware of the touchy subjects, the deeper issues. He makes that awareness known, but he says we’re not going to get into that in a logic class. This is rational philosophy. Metaphysics belongs to natural philosophy.
The other questions that he mentions are whether, if universals do exist in reality that is outside the human mind, whether they are actually material bodies or some kind of spiritual substances, obviously a profound question to investigate. And then whether they exist separately from the individual things that we see, which is what Plato taught, or whether they exist within those individual things, which is what Aristotle taught. He says, We’re not going to get into those controversial discussions that even these great philosophers, Plato and Aristotle disagreed on. He recognizes that quote “a discussion of this kind is most profound and requires another greater investigation.” And he’s referring there to the science of metaphysics. And he shows us that the mark of a good teacher is knowing what to include when teaching and what to leave for later. That takes discipline to be a good teacher who is patient like that.
He goes on to say, quote, “In what manner, however the ancients and especially the peripatetics, discussed these and the other proposed object of inquiry in a more logical manner, rather than philosophical or metaphysical manner, I will now endeavor to show you.” So he concludes, as he wraps up this introduction to the introduction, he concludes by stating the positive plan for this work that he’s writing for his students.
When he says the ancients, remember, he’s writing in the third century AD, so to us, he already is ancient. He’s referring to men who are ancient in his time, men who to people living in the third century AD were considered ancient, real ancients. So he talks about these ancients, and he’s referring to the followers of Aristotle who were called the peripatetics. And remember, just for the sake of chronology, Aristotle was teaching around 350 BC, that’s more than 500 years before Porphyry. So the followers of Aristotle were to him ancient, ancient philosophers. He says that’s where we’re going to get our content from, from the peripatetics.
Just in case you’re curious, Aristotle’s followers were called peripatetics because Aristotle used to teach while he walked around. It’s funny because I do something similar by accident. I publish what I call walk talks, where I go for walks, and I talk about subjects and answer questions that people ask. The reason I do that is because I used to host a lot of visitors. They’d come and visit my home, and we would always go on walks together. And we used to go for walks, and they would usually visit because they had questions they wanted to ask me or topics they wanted to talk about. And so we’d go on these walks and they would ask questions, and I would answer and we’d talk about things. And I really loved those times. I love those walks, and when those visits stopped, as my life changed and I got into other projects, I stopped having those walks, and I missed them. And so what I started doing was just going for walks, as if I was answering questions and talking about topics, and I would publish those talks as my walk talks. And that’s we learned that that’s similar to how Aristotle used to teach. He liked to walk about, and the Greek verb, peripateo means to walk about. So the followers of Aristotle were called the peripatetics, those who walk about named after the method of conversation and discussion that was common in Aristotle’s school. So that’s where that word peripatetics comes from.
When Porphyry says that he’s going to show how they discussed these topics in a more logical manner, he means that he’s going to focus on what’s important about these concepts, what the ancient philosopher said about them with respect to logical reasoning, not with respect to any metaphysical questions or higher philosophical questions.
So this choice of a method that Porphyry himself takes in this book reflects Aristotle’s approach of beginning when teaching, beginning with what is more knowable to us, things that we can understand from the beginning, before proceeding to what’s more knowable in itself, or to nature which is more perfect. Philosophical understanding, Aristotle explains that that’s how the mind moves towards wisdom. It begins with things that are knowable to us, things that are knowable to the senses, for example. But then we break them apart, and we analyze them and study them and understand the causes of them, and we gain a knowledge of them that’s very different from the knowledge we first had, but is actually more like the knowledge that God has of those things. We know them according to nature, as they are known according to nature.
So we can see in the way that Porphyry talks about understanding something in a logical manner, and then later understanding something in a metaphysical manner. He’s using that method of learning that progresses from things knowable to us to things knowable to nature, in the way that he lays out this introduction and how he introduces certain concepts and avoids discussing others. So he clearly establishes himself, Porphyry that is, clearly establishes himself as a faithful and wise guide who can lead us along a proper path of learning, who can prepare us for the greater investigations that we’re going to work through in our study of philosophy. So all of this is introduced to us in this opening chapter to Porphyry’s Introduction.
Memory Work
Now that brings us to the end of the content and the exposition of that content. And let’s establish some important points that are worthy of memorization, that summarize the content of this lesson. I have seven points of memory work that I’d like to share, seven items worthy of memorization.
Number one, the five predicables, the subject of this book. The five predicables are genus, difference, species, peculiarity and accident. The five predicables are genus, difference, species, peculiarity and accident.
Number two. Knowledge of the five predicables is necessary for understanding Aristotle’s Categories. Knowledge of the five predicables is necessary for understanding Aristotle’s Categories.
Third, the five predicables are essential tools for making definitions, divisions and demonstrations easy to remember because it’s three Ds, the five predicables are essential tools for making definitions, divisions and demonstrations.
Number four, Porphyry promises to give a simple introductory treatment of these concepts. Porphyry promises to give a simple introductory treatment of these concepts.
Number five, Porphyry deliberately avoids deep metaphysical questions about the nature of universals. Porphyry deliberately avoids deep metaphysical questions about the nature of universals, and remember, you don’t need to know all of these concepts at this point in your study. It’s just helpful to become familiar with these terms. You can always look them up on your own time.
Number six, Porphyry will focus on the logical use of the predicables rather than their metaphysical use or status. Porphyry will focus on the logical use of the predicables rather than the metaphysical.
And lastly, number seven, the peripatetics were the followers of Aristotle who developed and published his logical teachings. The peripatetics were the followers of Aristotle who developed and published his logical teachings.
Conclusion
So to bring this to a conclusion here, now that we’ve gone through all of the text, we’ve gone through the full exposition of the content, and have established some points of memory work to help summarize the content, we’ve studied chapter one of Porphyry’s Introduction. We’ve discussed, we’ve named and talked a little bit about the five predicables. We’ve talked about Porphyry’s approach, how he intends to teach in this introduction, we’ve talked about the difference between logical investigations and metaphysical investigations. And most importantly, I would say, we’ve talked about the relationship between this work, Porphyry’s Introduction and Aristotle’s Categories.
So having gone through this together and provided you with something of a pre-lecture for this study, it’s getting kind of ridiculous, because if you think about it, I’m giving you an introduction to Porphyry’s Introduction to Aristotle’s Categories. So we’re moving further and further from the real source text. So we want to make sure we keep our focus on Aristotle’s Categories as the goal.
Having gone through that introduction, it’s time for you to get to work in studying this lesson. Go and reread the lesson carefully. Follow the instructions in my article how to study for mastery. Read through the lesson. Study the lesson in detail. Take good notes to develop a clear understanding of the content of the lesson, and then develop your understanding and demonstrate your understanding by completing the lesson assessments that are included on the course page. Use the assessments as your guide to measure and judge your understanding. If you have any questions or need any help, visit the Academy Help Center or go to classicalliberalarts.com/support.
Once again, to wrap this up, my name is William Michael, the headmaster of the Classical Liberal Arts Academy. I hope that this lesson has been helpful. God bless your studies.
Mr. William C. Michael, O.P.
Headmaster
Classical Liberal Arts Academy
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