"Parmenides" is a profoundly complex and often confounding dialogue crafted by Plato. The narrative introduces us to a purported meeting between young Socrates and two esteemed philosophers of the Eleatic school, Parmenides and Zeno of Elea. The narrative structure primarily encapsulates the vigorous challenges posed by Socrates to the monist position of Parmenides and Zeno, wherein he refutes the contradiction of things being both similar and dissimilar by drawing distinctions between sensibles and Forms. He posits that sensible objects can exhibit paradoxical traits through their participation in Forms like Likeness, Unlikeness, Unity, and Plurality.
The dialogue proceeds with Parmenides dominating the conversation, scrutinizing Socrates' acknowledgement of Forms and interrogating him about the kinds of Forms he acknowledges. Parmenides provides five comprehensive arguments that challenge the Theory of Forms. These range from questioning how many particulars can participate in a single Form without causing it to separate from itself, to exploring the issue of infinite regress if a Form is also characterized by its attribute, to questioning the thought-existence of Forms, to dealing with the issue of the Forms being like their instances, and lastly, raising doubts about our knowledge of the Forms given their separate existence.
Even though Socrates fails to counter these arguments, Parmenides advocates the Theory of Forms, arguing that dialectic would be impossible without them. He encourages Socrates to undergo a form of philosophical training or exercise. The remaining part of the dialogue showcases such an exercise, with Aristoteles replacing Socrates as Parmenides' dialogue partner.
In the second part of the dialogue, three hypotheses are proposed, each exploring the existence and nature of the 'one.' This portion of the dialogue is considered challenging and offers an unadorned series of complex arguments. Throughout the centuries, scholars have attempted to decode this segment, but a conclusive interpretation remains elusive.
The dialogue has generated considerable commentary, particularly among Neoplatonists, and has been influential in the works of philosophers from the medieval era to the 15th century. Despite the debate and contention it incites, "Parmenides" continues to hold a significant position in philosophical discourses, chiefly for its exploration of topics such as Being, Sameness, Difference, and Unity.