Zhi Nuo's position in the history of western philosophy lies not in his new ideas, but in his defense of parmenides's ontology. He himself made it clear that his purpose was to "defend parmenides's views and oppose other critics". In form, Zhi Nuo's defense uses reduction to absurdity, but in content, it mainly focuses on two aspects: one is to demonstrate the existence of a single opposition, and the other is to demonstrate the existence of a static opposition movement. First, demonstrate from the angles of infinity and infinitesimal. If there are many, it must be made up of many parts. These parts either have a width and a thickness; Or lack of breadth and thickness. If there is a width and thickness, because the boundary of any part will not be at the outermost, this width and thickness can be infinitely increased; If there is no width and thickness, even if these parts add up forever, they are still equal to zero. So "if there are many, then there must be both big and small, from small to small, from big to infinite."
Second, demonstrate from a finite and infinite perspective. If there are many things, their number must be equal to the actual things, but if there are so many things, they are countable in number and therefore limited. On the other hand, if there are many things, they are infinite in number. "Because there is always another intermediary between things that exist, there will be other intermediaries between them, so there will be infinite things." First, "dichotomy". A moving thing must walk half the distance before reaching its destination, and after walking half the distance, it must also walk half the distance ... so divided, even infinite, that the distance between it and its destination is infinite, and it will never reach its destination.
Second, "Accili chasing turtles". Achille is the fastest hero in Greece, while the tortoise climbs the slowest. But Zhi Nuo proved that the fastest can never catch up with the slowest, because the pursuer and the pursued start to move at the same time, and the pursuer must first reach the point where the pursued starts, and so on. There is an infinite distance between them, so the pursued must always be ahead.
Third, "the arrow does not move." Any object must occupy a certain space, and it will lose its existence without its own space. The time an arrow passes through a certain distance can be divided into countless moments. At every moment, the arrow occupies a space the same size as itself. Because the arrow is always in its own space, it is still.
Fourth, the "sports ground". There are two rows of objects with the same size and number. One row is from the end point to the midpoint, and the other row is from the midpoint to the starting point. When they move in opposite directions at the same speed, there will be contradictions in time. Zhi Nuo thinks this can prove that half the time is equal to twice the time. Zhi Nuo's above argument, except that "sports ground" is obviously sophistry, the rest contains profound significance. They involve finite and infinite, indirect and continuous, the relationship and boundary between time and space, etc. , which has aroused the thinking of philosophy, logic and mathematics, is still a research topic of people. His argumentation method has also played a positive role in promoting the development of argumentation and logic. Because of this, Aristotle praised him for discovering dialectics, and Hegel also called him the founder of conceptual dialectics.