Discussions
Map compliments of the Oxford Classical Dictionary. See https://oxfordre.com/classics/page/maps/maps-of-the-ancient-world.
Studies
The Presocratics
The philosophers before Socrates focused on how the world arose and how it works. They wrote speculatively about nature and the cosmos. Some challenged the possibility of science. And some emphasized practical studies about how people can get along or get ahead in the world. Their speculations led to advances in scientific knowledge.
Socrates
Socrates turned away from cosmology, and while he was fascinated with efforts of the Sophists to pursue on practical subjects, he himself insisted that what we should concern ourselves with was not our own success but what is right and wrong, good an evil. He turned philosophy towards ethics and moral theory.
Plato
A follower of Socrates, Plato wished to put the study of ethics on a firm foundation by developing a science of reality, or metaphysics, a science of knowledge, or epistemology, and studies of political science, education, aesthetics, and, eventually, natural science. He saw the world of experience as subject to an ideal realm.
Aristotle
A student of Plato, Aristotle never accepted his mentor's focus on the ideal realities of another world. He saw the ground of reality as concrete physical objects, from which ideal or universal entities were but abstractions. He developed a powerful account of science, and divided knowledge into most of the departmental studies that make up the modern curriculum.
Early Science
Early Greek science was deeply influenced by most of the early thinkers. The Presocratics believed in making and testing hypotheses. They invented concepts such as those of sources, principles, elements, compounds, atoms and empty space. Aristotle formalized logic and also took over the concept of a logic of scientific discovery and proof from Plato.
Recent Discussions
21.8 Knowledge as True Judgment with an Account
Now Theaetetus remembers hearing someone say that knowledge is true judgment with an account (logos). According to his source, things that lacked an account were not knowable. Socrates offers a “dream” to help clarify the proposed definition. “I think I have heard people saying that the first components, like elements (stoicheia), from which we and everything else are composed, lack an account.” This, according to ancient commentators, is the first extant use of the term stoicheion as ‘element.’[56] This suggests the analogy to letters of the alphabet (also called stoicheia),
21.7 Knowledge as True Judgment
Overwhelmed by objections to the thesis that knowledge is perception, Theaetetus abandons it. Socrates asks him for another definition. He replies, it consists of judging (doxazein). Socrates plods him to be more specific. Theaetetus observes that there is false as well as true judgment, so “True judgment would have to be knowledge.”[52] Socrates addresses the question of false judgment, which has remained a thorny problem in Greek philosophy. In Greek idiom the phrase legein ouden, literally: ‘say nothing’ means to speak falsely or lie. But how can one say
21.6 Heraclitus Redivivus
Plato allowed Protagoras to defend himself against a too-hasty refutation. He does not offer the same opportunity to Heraclitus. But perhaps we should. Plato famously reported, “Heraclitus, I believe, says that all things pass and nothing stays, and comparing existing things to the flow of a river [potamou rhoēi], he says you could not step twice into the same river.”[45] Plato is evidently alluding to Heraclitus’ “river fragment,” fragment 12, which goes like this: On those stepping into rivers staying the same other and other waters flow.
21.5 All Is in Flux
Socrates turns now to the second inspiration for saying that knowledge is perception. According to Heraclitus, he has already pointed out, everything in the sensible world is in constant flux. He and Theodorus remind us that the flux doctrine goes back at least to Homer, and perhaps much earlier, for according to the ancient myths things originate with Oceanus and Tethys, which are flowing streams (see ch. 21.2* above).[39] On the other hand, Socrates points out, Parmenides and his follower Melissus claim that everything is one and unchanging. So
21.4 Knowledge as Perception and Man as the Meature
At this point in the dialogue, we have Theaetetus’ definition of knowledge, that it is sense perception, buttressed by the alleged insight of Protagoras that man is the measure of all things, and by the alleged insight of Heraclitus that everything is in flux. Now Socrates raises some preliminary objections that call into question the definition under consideration. If we accept the fact that man is the measure of all things, Socrates asks, why not say that a pig is the measure of all things? Why not say a
21.3 What Is Knowledge?
The dialogue that constitutes the sequel to the Parmenides is the Theaetetus. It begins with a short introduction in which Euclides of Megara, the philosopher who had hosted the Socratics in a retreat after the death of Socrates (see above, ch. 6.1*), shares with his friend and countryman Terpsion a manuscript in which he recounts a conversation between Socrates and Theaetetus.[23] The young man was a promising student of the mathematician Theodorus and came to be a member of Plato’s Academy.[24] At the time of the reading, Theaetetus has recently
21.2 From Heraclitus to Plato
We are confronted with a developmental story that sounds very Hegelian. First there was Heraclitus, who said all was flux. Then there was Parmenides, who said all was at rest. Then there was Plato, who said that the sensible world was flux, the world of Forms was at rest, and whatever order could be found in lower the sensible world owed its stability to the upper world of Forms. Thesis, antithesis, synthesis. This is not, to be sure, Hegel’s story, but it does seem to represent Plato’s general take on
21.1 Plato and Heraclitus
In the Parmenides, Plato brought his mentor and hero Socrates face to face with Parmenides of Elea, the most imposing and reverend figure of early Greek philosophy. He also introduced Parmenides’ most famous student, Zeno of Elea. Parmenides and his followers were famous for declaring that there is no change: there is only what-is, complete and perfect and unalterable. In what seems to be the sequel to the Parmenides, the Theaetetus, Plato will confront the other pillar of Presocratic philosophy, Heraclitus of Ephesus. Heraclitus is, moreover, the polar opposite
20.10 The Moral of the Story
So what are we supposed to learn from the attacks on the Theory of Forms in the first half of the Parmenides and the litany of arguments in the second half? According to Samuel Rickless, in his intensive study of the dialogue, we are to learn that four of the assumptions of Plato’s Theory of Forms are untenable. The arguments of the second half have shown that they lead to contradictory results and so must be abandoned. Dialogues written after the Parmenides show that Plato does indeed modify his
20.9 Aristotle on the Third Man
There is something very Aristotelian about the Third Man Argument—including the name. For Aristotle (but not Plato), the most real things are biological specimens, like Man (in the sense of a human being, member of the species Home sapiens). For Plato a non-substantial property like Largeness will do quite well as a Form. Furthermore, Aristotle is a logician—quite literally. He invented the first system of logic in his treatise Prior Analytics. Plato can recognize logical fallacies, but he has no system of logic, nor does anyone else before Aristotle. Aristotle
20.8 The Third Man Argument
The Parmenides is an unprecedented, baffling, and even bizarre dialogue. Two towering philosophical figures of yesteryear come to town, meet the young and up-and-coming Socrates, listen to him expound his theory of forms; Parmenides criticizes it, causing Socrates to despair; he then encourages him not to lose heart, but hone his philosophical skills, for which Parmenides offers an extended opportunity. What should perhaps strike the reader is the fact that, for the first time ever in the Platonic corpus, Plato’s pet theory, the Theory of Forms, is put examined
20.7 Paradoxes of Being
Now come 29 pages of deductions without intermission. There is a logical order. First we suppose that there is a One. We then prove that for a number of properties F, the One is not-F, and also not the contrary of F, in relation to itself and in relation to the Others. Second, we suppose again that there is a One. We then prove that the One is F and also the contrary of F, in relation to itself and in relation to the Others. Third, we suppose again that