If twenty six hundred years of western philosophy has told us nothing more, it has made one fact clear. There can be but one criterion for truth and that must be the faith we have in the source of that truth. Thus, change was the nature of the sixth century BC Ionian world and change was the only truth they knew. It has long been held by philosophers that if we possessed some single indubitable truth the we could deduce all of the truths of the world from it. But if the only truth is change, then it is not possible to obtain knowledge of even a single truth since as soon as it was found it would become something else, it flits through the fingers. Once touched it is gone. It has become something else not yet touched, it too never to be possessed. The great advance of the Milesians was that even as they sensed this they realized that it was not necessary to hold the truth to gain knowledge. Now, these two concepts, truth and knowledge, are so imbedded into western civilization that there is nothing more important for us than to understand the particularly western relationship between them.

In the Milesian world experience dealt with things and truth with change. From this it can be deduced that everything must be made of the same thing, otherwise change from one thing to another would not be possible. Of course this is all old ground but perhaps you had not realized how important this development was to the emergence of western civilization. As long as every change can be blamed on the whim of the gods or nature, truth is only what is found and if it is changing then so-be-it. One cannot question the will of the gods. On the other hand, if truth is change then the gods, though they may be participants, are not the source of change. The source of change is truth itself and the source of truth is experience.

Experience is of things and it is things that undergo change. At the same time, if it is not possible for truth to change then it is obvious that those elusive things through which we experience change can neither be touched nor known. What we can know about them is only that which is necessary in order that they can in fact be changing. This, of course, is quite simple, if everything changes from one thing to another then all things must be made up of the same thing. For Thales that was water, for Anaximander the boundless, and for Anaximenes air. Hericlitus, of course, made the underlying substratum change itself but this was because his source of truth was the divine logos, or what lay behind change and not change itself.

This short review of Ionian philosophy should remind us that they never suggested that we could know truth itself as long as we consider knowledge to be derived through reasoning and truth through experience. That we could know truth was suggested first by Parmenides who said that for something to come into being it was necessary that it not be at one instant and then be at the next. This is a contradiction. We cannot speak of what is not. What is cannot be derived from what is not. Something cannot come out of nothing. This is true because its denial would be a manifest contradiction. But, if we accept this as true then we must admit that there can be no change because then everything that changes would both be and not be. How can this Eleatic view be so different from the Milesian, particularly since the Eleatic vision was derived in some extent from the Milesian? The difference lies in the Ionian concept of truth as change and the Eleatic concept of truth as being.

The difference between these views was derived from their two sources of truth. For the Ionians the source was experience in a world under-going one of the greatest cultural clashes of all time. The Eleatics, though living in the same changing world as their eastern contemporaries, were more isolated from the frontiers of change. They were also an outgrowth of Pythagorean number mysticism and their source of truth was not experience but reasoning. That something cannot be and not be at the same time is not something that can be determined by experience because experience is rooted in time. Experience taken over time is highly inconsistent and not the kind to be possessed. Plato's derivation of truth is in a direct line with the Eleatics. He said that there existed a world of pure forms, that these alone were real, and that only from these could someone gain knowledge. Note that this is a considerable modification from Parmenides one which was alone was real and which could not be involved in change or movement. The Eleatic world was dead. The world of the senses may not have been real for either, but Plato's sensual world could at least exist by participating in the forms. Plato's world could both be in the sense of being rationally developed, and exist in the sense of being experienced. Where was the source of this new truth, one that found stability in the midst of turmoil? Plato's source of truth lay in the stability of the Greek City-State, particularly Athens. For all Athenians believed that their city had existed since time immemorial, Regardless of the changes of man and the whims of the Gods, they believed Athens to be a solid bedrock. This belief was not shaken until the defeats of the Peloponnesian wars. Aristotle, of course, was a northern Greek with Macedonian leanings and not an Athenian but he derived his early training in Athens under Plato and his later inspiration out of the stability of the Alexandrian empire, and the inspired political skills of his former pupil. But on the death of Alexander, followed a year later by the death of Aristotle, all of this stability came to an end. Alexander's generals who divided the empire between them did not share in his gift for governing. Faith in the stability of the world, and on the great truth systems that stemmed from it, dissipated. The next five hundred years until the time of Augustine and the solidification of Christianity, nothing became more obvious in the outlook of philosophy than this loss of the classical faiths of truth and the relentless search for a new faith.