Parmenides (see “Th e Elements” on pages –) believed that our senses deceive us by exposing us to illusions while concealing the underlying reality. Th is strongly infl uenced Western history’s second most famous philosopher, Plato ( or – or ...). Th e most famous of all philosophers was Socrates (ca. – ...).
Plato studied under Socrates and admired and loved his teacher.
Plato was born and died in Athens. A mathematician, sociologist, and political theorist, he founded the Academy in Athens in about
... and presided over it until his death. Th e Academy was a kind of debating society. It was not open to the public, although it charged its members no fees.
Plato was an aristocrat related to people linked to the tyrants who ruled Athens, and he lived in troubled times when Athens was at war.
Two of the tyrants were his uncles. Plato bitterly hated democracy, a hatred that is clearly expressed in the books of his Republic. In the Republic, written in the form of a dialogue in which Socrates explains matters to his friend Glaucon, Plato describes the political structure of what he regards as the ideal form of government: It is a totalitar- ian dictatorship. Th e book has been highly infl uential throughout history. In his History of Western Philosophy Bertrand Russell wrote:
“Why did the Puritans object to the music and painting and gorgeous ritual of the Catholic Church? You will fi nd the answer in the tenth book of the Republic. Why are children in school compelled to learn arithmetic? Th e reasons are given in the seventh book.”
Troubled times are times of rapid change, so perhaps it is not surprising that Plato believed that all change was for the worse. He sought permanence but found only change, and in his pursuit of per-
manence he developed the ideas of Parmenides, expounding them in books V to VII of the Republic. Plato deals fi rst with the meaning of words. For example, everyone knows what a dog is, but if someone says dog the word might suggest a terrier to one person, a spaniel to another, and a St. Bernard to a third. Th e word table describes many diff erent kinds of objects, all of which are tables. But what is it, Plato asks, that all these diff erent dogs and tables have in common?
Clearly, it is some quality of dogness or tableness, some basic, defi n- ing characteristic. If someone points to an actual dog, there was a time before that dog was born. It has not always existed. Th e same is true of a particular table, which must have been made by someone at some past time. Dogs and tables come and go, and the same is true of everything else in the world. Change is everywhere. But dogness and tableness are always there in the background as the abstract qualities that make it possible to identify objects. Th ere is the permanence Plato sought.
Th e argument then moves away from Parmenides and becomes metaphysical. Metaphysics is the branch of philosophy concerned with ideas of being, knowing, and the mind. Plato maintains that words describing objects must refer to original models—archetypal examples of those objects created by God. So all dogs and tables can be identifi ed by reference to the archetypes, which have the essential qualities all dogs and tables possess. Th is applies not only to objects but also to qualities such as colors.
Th e archetypes are ideas or forms, and this part of Plato’s phi- losophy is called the theory of forms. Its central point is that only the forms are real. Th e particular examples of the forms that people see, hear, touch, taste, or smell are only apparent. Th ey are illusory. Plato explained his theory of forms in the following allegory (in the transla- tion by Benjamin Jowett) at the beginning of book seven:
And now, I said, let me show in a fi gure how far our nature is enlight- ened or unenlightened:—Behold! human beings living in an under- ground den, which has a mouth open towards the light and reaching all along the den; here they have been from their childhood, and have their legs and necks chained so that they cannot move, and can only see before them, being prevented by the chains from turning their heads.
Above and behind them a fi re is blazing at a distance, and between the fi re and the prisoners there is a raised way; and you will see, if you look,
a low wall built along the way, like the screen which marionette players have in front of them, over which they show the puppets.
I see.
And do you see, I said, men passing along the wall carrying all sorts of vessels, and statues and fi gures of animals made of wood and stone and various materials, which appear over the wall? Some of them are talking, others silent.
You have shown me a strange image, and they are strange prisoners.
Like ourselves, I replied; and they see only their own shadows, or the shadows of one another, which the fi re throws on the opposite wall of the cave?
True, he said; how could they see anything but the shadows if they were never allowed to move their heads?
And of the objects which are being carried in like manner they would only see the shadows?
Yes, he said.
And if they were able to converse with one another, would they not suppose that they were naming what was actually before them?
Very true.
And suppose further that the prison had an echo which came from the other side, would they not be sure to fancy when one of the pass- ers-by spoke that the voice which they heard came from the passing shadow?
No question, he replied.
To them, I said, the truth would be literally nothing but the shadows of the images.
Th at is certain.
Th e allegory of the prisoners in the cave is meant to show that the world we see around us is but a shadow of the real world of forms. Th ere is no way anyone could investigate the theory of forms, so it cannot be proved or disproved and therefore is not a scientifi c
theory. It has had one interesting consequence, however, and one that refl ects exactly Plato’s desire for permanence. If the objects and quali- ties in the world are illusory and each refers to its form, which is the only reality, then species of plants and animals are fi xed. Th e chee- tah that hunts on the plains is an illusion, but God has made a real and unchanging cheetah that stands for all cheetahs, and the same relationship applies to every species. Animals, in Plato’s philosophy, cannot evolve.