Plato's and Aristotle's Answers to the Parmenides Problem

THE QUESTIONS RAISED by great pre-Socratic philosopher Parmenides were perhaps main challenge for Plato and Aristotle, two of greatest post-Socratic philosophers. To summarize challenge briefly: Parmenides denied that there was any change in world. Although average person has intuitions from sense experience that run contrary to this claim, Parmenides had a logically valid argument that proved his theory. Parmenides denounced intuitions of sense experience as falsities, way of opinion. The way of truth was to accept his theory, that there is no change, all being is one, and multiplicity of individual beings is a mere illusion. Parmenides' line of argument is as follows. Change is coming into being. If something comes into being, it comes into being from something that existed before. What was it before? There are only two possibilities, which make up Parmenides problem: either : 1. Being comes from being. or: 2. Being comes from nonbeing. If #1 is correct and being comes from being, in that case same thing exists before and after, and no change occurs. If #2 is correct and being comes from nonbeing, in that case nothing comes to be. Nothing comes from nothing after all, so no change occurs. The conclusion is that there is no such thing as nonbeing, and no such thing as change. The world is all one being, and there is no division into separate individual beings that interact and change. If Parmenides' argument seems tricky, it ought to. It has seemed tricky to all thinkers who have followed Parmenides. There were even a few unscrupulous thinkers who took advantage of this trickiness and used it as a justification for moral relativism. These thinkers were sophists, and most brilliant of them was Protagoras. Protagoras claimed that each individual man was the measure of all things, so same thing that was good for one man might not be good for another based on perspective. (1) Ultimately, Protagoras claimed there was no measure of goodness based on human nature because human nature as a separate individual form did not exist. Only being exists, as Parmenides argued; Protagoras said rest of what we take to be reality is an illusion and subjective. Protagoras' argument is a stronger version of sophist arguments about convention and nature (nomos and phusis). As Plato and Aristotle both recognized, Parmenides problem had implications for politics as well as for philosophy. No philosopher was able to accurately interpret and refute Parmenides problem until Plato and Aristotle. Plato answered it in an important way in his dialogue Sophist, and Aristotle followed this up with complete answer in Physics book 1, chapter 8. My thesis is that Plato's answer would have been good enough to defeat Protagoras in extended argument, thereby remedying political aspects of Parmenides problem. However, Aristotle's answer is required to answer some additional philosophical and scientific aspects. The first section of this paper will summarize history of pre-Socratic philosophy and explain why Parmenides was a turning-point. The second section will explain sophist Protagoras' relation to Parmenides problem. The third part will present Aristotle's complete answer to Parmenides problem, and in fourth part I will compare that approach with Plato's solution in Sophist. Lastly, I will sum up by characterizing how I think Plato and Aristotle would have responded to Protagoras' Parmenidean sophistry in political life. I From what we know about early pre-Socratic thought, speculations of philosophers did not clash against intuitions of average man as they did after Parmenides and sophists. The typical pattern of school of Miletus was to propose an underlying element that could explain world that philosophers experienced around them. Thales proposed water, Aniximander proposed the indefinite, and Anaximenes proposed air. …