Born: 384 BCE Greece ancient Greece Died: 322 BCE Chalcis Greece Founder: Lyceum Notable Works: “Categories” “Eudemian Ethics” “History of Animals” “Metaphysica” “Nicomachean Ethics” “Ode to Virtue” “On Generation and Corruption” “On Interpretation” “On the Generation of Animals” “On the Heavens” “On the Parts of Animals” “On the Soul” “Organon” “Physics” “Poetics” “Politics” “Posterior Analytics” “Prior Analytics” “Protrepticus” “Rhetoric” “Sophistical Refutations” “Topics” Subjects Of Study: category ekthesis element idea predicable
Truth’, which was revealed to him, he claims, in meeting with a goddess, Parmenides distinguishes between an inquiry into what is and an inquiry into what is not. The latter, he says, is impossible. ‘One cannot know that which is not – that is impossible – nor utter it; for it is the same thing that can be thought, that is’. The essence of this somewhat cryptic argument is that in order to think of something which is not – let us say, ‘a unicorn’ for example – one must be thinking of something: there must be some idea present to the mind, presumably the idea of a unicorn.
But to think of a unicorn means that the unicorn (or the idea of a unicorn) exists in the mind, and therefore it cannot be truly said that unicorns completely fail to exist. The argument turns principally on two complex issues.
Sobre o ser e o nada
First, exactly what is meant by ‘exists’ here? What is the difference between existing in the world and existing in the mind? This begins a controversy that will reappear throughout much of the history of philosophy in many different contexts, but most notoriously in Anselm’s ontological argument, some 1500 years later. Second, what are the connections between
If that debate started with Parmenides, it has taxed almost every major thinker ever since, up to and including the seminal works of the twentieth century by philosophers such as Bertrand Russell, Ludwig Wittgenstein and W.V. Quine.
Since Parmenides thought that to think of something is to give it some semblance of existence, then one cannot think of anything that is truly ‘not’. It follows that one can only think of that which is. Now comes the second part of Parmenides’ deductive reasoning, the first known example of a formal deduction in the history of Western thought. For to think of anything that is implies the existence of something that is not.
If something is green, it is not red, if something is a man, it is not a dog, a house is not a cart, and so on. But since by his previous argument Parmenides has shown that negative existential claims are impossible, it seems one cannot make positive existential discriminations either. To distinguish X from Y, is to say that X is not Y, precisely that which Parmenides claims is impossible. Therefore, one cannot logically discriminate between different things in the world. One can only say, Parmenides concludes, that everything is and hence, the true nature of reality – that which is – must be that of an undivided, homogenous, single entity. By similar argument Parmenides attempts to show that change is also impossible. If one can think of something that will exist in the future, then it must exist in one’s mind now. If one can remember something or someone that has passed away, then they must be present to your mind at the time you are thinking of them.
Therefore, Parmenides concludes, coming into being and passing away are illusory, change is illusory: everything is one, undivided, changeless and eternal. It is clear to the modern reader that Parmenides’ reasoning is unsound, but it would not be until the rise of modern philosophical logic in the late 19th and early 20th centuries that negative existential claims would be clearly understood. However, apart from the historical importance of the first known attempt at logical deduction, later to be perfected in the work of Aristotle, Parmenides is significant for highlighting the intricacies and logical complications inherent in the notions of existence and the relationship between language, thought and reality.