compounds. Philosophers writing after Parmenides did not abandon cosmology (except for a few followers of his), but rather proposed more elaborate theories of elements. Empedocles posited four elements: earth, water, air, and fire, a theory so influential that it lasted until about AD 1600. These corresponded roughly to the great cosmic masses of Earth, sea, atmosphere, and fiery heavenly bodies, and they could be supposed to combine to form all other stuffs, including flesh, bone, wood, and iron. About the same time, Anaxagoras posited an unlimited number of elements that could mix together or emerge as the dominant member of the mixture. The most powerful theory that appeared in the fifth century BC was that of the atomists, Leucippus and Democritus, who posited microscopic particles of matter of different shapes that could combine into objects of all kinds.
In the second half of the fifth century BC, a new movement arose of itinerant teachers known as sophists, who traveled about the Greek world lecturing and attracting (paying) students for short courses. The sophists were steeped in the cosmological theories of their predecessors, and some of them taught such theories to wide audiences, but mostly they offered “practical” subjects that were in demand in the new democracies that arose in this period: public speaking, political theory and practice, and financial management. Some sophists promised that their students would learn to win any debate they entered into. These kinds of claims raised ethical issues of whether one could win an argument even when one was defending a falsehood. Indeed, some sophists raised questions concerning whether good and evil, right and wrong were natural concepts, or whether they were human inventions.
Here we meet Socrates (Chapter 3), who arose out of the same culture as the sophists but challenged their sometime immoral or amoral teachings. Unlike the know‐it‐all sophists, he professed not to have any special knowledge. Yet he made tireless efforts to discover the nature of virtue and concepts of right and wrong, asking what virtue was and whether it was teachable (as the sophists assumed it was). Socrates’s question‐and‐answer method and his careful analyses of ethical concepts turned philosophy away from cosmological speculation on the one hand, and from education for political success on the other. In the tumultuous age of the Peloponnesian War which pitted Greek city‐states against each other and brought out some of the worst of human passions and hostilities, Socrates was the self‐appointed gadfly and conscience of his home city of Athens. Somehow, despite his claims to lack any special knowledge, he managed to live a life of spectacular virtue, standing up to the powers of his city a number of times on matters of moral significance. Although he wrote nothing and claimed not to be a teacher, he gathered around him a number of brilliant young men who would carry on his movement into the fourth century BC. When he was accused of impiety and corrupting the youth and put to death by the democracy, his followers vowed to vindicate their master.
Soon after Socrates’s death, his students began publishing reminiscences and fictionalized conversations in a new genre, philosophical dialogues, which recreated the philosophical discussions of their master. The most successful of these students, as a writer, philosopher, and teacher, was Plato (Chapter 4). Plato seems to have had the philosophical acumen to understand Socrates as many of his other followers did not. And his literary skills allowed him to bring Socrates to life as no one else could. Plato contributed many of the dialogues that portrayed Socrates. As a citizen of Athens, Plato also had political ambitions. But his early experiences with the government of the Thirty (see Chapter 4) and with the trial and death of Socrates turned him into what Socrates never admitted to being, a professional philosopher. Plato founded the Academy, which gathered many of the brightest minds of Greece. His own works were almost all dialogues, mostly featuring Socrates as the protagonist. But scholars have identified works that seem to present Socrates’s ideas and methods, and those that present Plato’s ideas and methods. In the latter works, Socrates becomes a mouthpiece for Plato rather than a recreation of the historical figure.
Whereas Socrates was exclusively a moral philosopher dealing with ethical issues, Plato saw a need to support moral philosophy with a strong theory of knowledge (epistemology), a strong theory of reality (a metaphysics), and a theory of the soul (psychology). He posited the existence of eternal realities he called Forms, such as Justice itself, Equality itself, and Goodness itself. He treated abstract concepts such as these as ultimate beings. He viewed the world we live in as a world of Heraclitean change with no permanence. Whatever order and constancy it had, it owed to a connection with the Forms, which he called “participation” or “imitation.” He believed that humans have eternal souls that inhabit human bodies through a cycle of reincarnations. When the soul was outside the body it was more in touch with the Forms than when it was in the body and distracted by its needs. The human soul in a mortal body had a dim awareness of the Forms; by a process of “recollection” it could come to reacquaint itself with the Forms themselves and appreciate them more fully. Plato saw Socrates’s question‐and‐answer method as providing the means to help us rediscover the Forms.
Plato went on to develop the political theory, a theory of art, a theory of education, and many other theories grounded in his Theory of Forms and its attendant principles. Plato offered the first comprehensive theory of everything in the Western tradition.
Plato’s most important student was Aristotle (Chapter 5), an orphan from an important family in northern Greece. Aristotle spent 20 years in Plato’s Academy and then, on Plato’s death, lived in northern Greece until the last part of his life, when he returned to Athens to found his own school, the Lyceum. It appears that even as a young student Aristotle was critical of Plato’s Theory of Forms, and he invented or developed a number of important objections to the theory. According to Aristotle, the ultimate realities were not abstract entities but concrete things such as Socrates the human and Fido the dog. Aristotle provided the first rigorous ontology, or theory of basic realities, in which he distinguished between individual things (“particulars”) and general types (“universals”) on the one hand, and things (“substances”) and properties (“accidents”) on the other. For Aristotle, the ultimate realities were in the class of particular substances, whereas universal substances and properties were dependent for their reality on particular substances. Thus Doghood exists because things like Fido and Fifi exist, and not vice versa; and Justice exists because there are just people like Socrates and Pericles. This allowed Aristotle to advertise himself as a philosopher of common sense who believes in realities we are all acquainted with, rather than being forced to posit mysterious entities such as Platonic Forms or Democritean atoms, which are not accessible to us.
While Plato offered the first comprehensive philosophy, Aristotle offered the first systematic philosophy. He invented the first theory of logic, which he applied to the philosophy of science. He developed his own cosmology, biology, meteorology, psychology, ethics, political theory, rhetoric, philosophy of art, and so on. While Plato covered some of these areas (he shied away from scientific theories in general), Aristotle was unique in compartmentalizing areas of study so that they could be studied rigorously and in depth. Where Plato tended to offer wonderful analogies like those of the Sun, the Line, and the Cave in the Republic, Aristotle offered rigorous argument for almost all of his claims. In retrospect, he was wrong in many of his theories; but he never assumed anything, and rarely let an image stand in for an argument. He seems to have thought of everything and to have covered all his bases when he presented a theory. When his works were recovered in the late medieval period, philosophers tended to be overwhelmed by his system and to accept it as gospel truth. Although Aristotle was a prodigious scientific researcher who, for instance, studied numerous zoological species in the field, collected specimens he dissected, and made important astronomical observations, many of his medieval followers knew him only as a theorist.
After the death of Aristotle, Athens became the home of new movements in addition to the schools of Plato and Aristotle (Chapter 6). The Hellenistic period, after Alexander the Great’s conquest of the Persian Empire, was a time when Greek culture was exported throughout the Mediterranean and Middle East. Philosophers in Athens