The Development of Greek Philosophy (Part 2)

Philo of Man




The Problem of Epistemology:
The Development of Greek Philosophy (Part 2)


The Problem of Epistemology

In Part 1 of this series of discussions about the development of Greek philosophy, we learned that for Parmenides and the Eleatics, there is no world-process. Now, if there is no world-process, then this means that there is no “process” or any “change” that actually happens in reality. The implication of this argument in epistemology is that there is no mental process and, for this reason, knowledge is impossible to attain.

If there is nothing but process or change, and nothing whatsoever is permanent, as Heraclitus would have us believe, then neither subject nor object continues. Hence, there is neither a knowing subject nor a thing to be known. If this is the case, then the same conclusion can be arrived at, that knowledge is impossible to attain.

If there is nothing but mechanical process, nothing but the union and separation of the four basic elements, as Empedocles and the Atomists believed, then there is also no mental process, and so, knowledge is also impossible to attain.

And if a mental process depends upon a being (Nous or Mind) outside the world, as Anaxagoras maintains, then there is no natural process of knowledge. For this reason, human knowledge is impossible to attain.

The overall implication of Heraclitus, Parmenides, Empedocles, the Atomists, and Anaxagoras’s philosophy in epistemology is that knowledge cannot be attained. More importantly, if there is no knowledge, then this implies that there is no truth.

And if there is no truth, then nothing whatsoever is “in itself”, that is, there is nothing that exists as universally valid being or truth, neither in science nor in philosophy. At the end of it all, nothing remains but subjective opinion; nothing but the individual as the measure of all things. This is precisely the theme of the Sophists, particularly Gorgias and Protagoras.

As is well known, the Sophists in general were convinced that knowledge is impossible to attain. As Protagoras claims: “Man is the measure of all things, of the reality of those which are, and the unreality of those which are not.” Another famous line of Protagoras reads: “As to the gods, I cannot know whether they exist or not; too many obstacles are in the way, the obscurity of the subject and the shortness of life.” For more on the life and works of Protagoras, see Internet Encyclopedia of Philosophy,

It is important to note that Sophism as a philosophical movement (philosophical movement because it’s not a branch nor a sub-branch of philosophy) is partly an expansion of the philosophies of Heraclitus, Parmenides, Empedocles, the Atomists, and Anaxagoras, but in the realm of knowledge.

Now, with the contention of the Sophists that knowledge is impossible to attain, Socrates came into the fore, which gave way to Plato and, later, Aristotle. Needless to say, this is where Socrates, Plato and Aristotle entered the scene.

Socrates (Photo credit: Free Wikimedia Commons)

Socrates (469 BCE – 399 BCE), indeed, was the first to see the problem with Sophism. In fact, the primary question that preoccupied Socrates was nothing else than the genesis of knowledge, the passage of the mind from the stage of “not-knowing” into that of “knowing”, and the seeking of truth, with a factual refutation of the Sophists who declared that knowledge is impossible to attain.

One of the proofs why the Sophists believed that knowledge is impossible to attain is the continual contradiction of human opinions about anything. Thus, the Sophists believed that knowledge and truth are impossible to attain because people disagree on almost everything.

However, Socrates was convinced that “harmony” or “agreement” is inherent in any disagreement. Thus, Socrates believes that “harmony” or “agreement” can be produced out of the contradiction. This made Socrates conclude that truth and knowledge are possible, and that they can be found in intercourse with men, that is, in a dialogue with men. Thus, for Socrates, with dialogue, universal concepts―those in which all men agree―are made possible. For more on the life and works of Socrates, see Internet Encyclopedia of Philosophy,

Plato (427 BCE – 347 BCE), as we know, was Socrates’s most brilliant student. Plato was a philosopher in his own right. However, Plato’s philosophy began with his attempt to write or record Socrates’s philosophy. As we know, Socrates never wrote his philosophy. Later, however, as he expands Socrates’s philosophy, Plato developed his own way of philosophizing and, eventually, his own philosophy.

Plato agreed with Socrates’s claim that universal concepts―those in which all men agree―are true concepts, which are the objects of knowledge. The strong proviso that Plato added is that everything that exists is just a copy of the real. Thus, the world of ideas (in contradistinction to the world of matter or the material world) is the only real world and, consequently, the only real knowledge. For sure, this is the step from Socrates to Plato.

Plato’s notion of the world of ideas and the world of matter laid down the notion of the dualism of matter and form. And this dualism implies the opposition of ideas and matter, that is, of the intelligible world and the material world. For more on Plato’s life and works, see Internet Encyclopedia of Philosophy,

But the question of the inquiring mind was: how does matter acquire form? In other words, how is the union of matter and form possible? This question gave way to the philosophy of Aristotle.

Aristotle (382 BCE – 322 BCE) got rid of Plato’s dualism. For Aristotle, form and matter are inseparable. This is because, according to Aristotle, we cannot think of anything without matter and form. Indeed, for Aristotle, something cannot exist if it does not have both matter and form, that is, if it is not complete. This is the reason why Aristotle argues that anything that exists is perfect, is complete, because it has matter and form. For example, a table cannot exist as a table in reality if it does not have a form of a table and matter of which it is made.

However, Aristotle argues that it is form that actualizes the potentialities of matter. This explains exactly Aristotle’s principle of act and potency.

Furthermore, Aristotle introduces the idea of a Prime Matter. According to Aristotle, Prime Matter is the source of everything, and this Prime Matter has the possibility of becoming something. For more on Aristotle’s life and works, see Internet Encyclopedia of Philosophy,

Lastly, but most importantly, it must be noted that with Aristotle, the classic period of Greek philosophy ends.


Below is the front cover of our book in philosophy of the human person, a core subject in senior high schools in the Philippines. Chapter 1 of this book discusses the problem of knowledge, that is, epistemology. If you are interested to purchase the book, you may contact the publisher at For more on the basic information of this book, please visit this link:

Introduction to the Philosophy of the Human Person (Edited by Jeffry Ocay)



Professor of Philosophy
Silliman University

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