In ancient Greece, the value of truth was a highly ascertained goal sought out by the most influential minds of the time. Both Plato and Aristotle, followers of Socrates and the Sophists, were certainly among the forerunners in this pursuit. They both developed new theories on systems of thought based on the new ideas presented by the Sophists. Plato took into account Socrates’ concepts and expanded upon them, passing along his thought/knowledge to Aristotle. In his own pursuit of the truth, Aristotle was not afraid to prove his teacher wrong and go against his theories.
For instance, Aristotle boldly states his own theory of universals and systematically debunks Plato’s theory of universals in the Posterior Analytics and the Metaphysics. While Aristotle doesn’t fully contradict Plato in his theory, he does disagree on some major points, such as the nature of universals and particulars. Regardless of the particular differentiations of the details or natures of these concepts, they both agree that universals and particulars exist in the world. While Plato himself even addresses the holes in his own logic, I see problems in more than just the holes.
Plato’s argument for the existence of universals and particulars (and by extension, the soul) is foundationally flawed. Plato was the first person to posit the real existence of abstract entities that can’t be perceived with the senses. He called these entities ‘Forms’ (which ultimately are the proto-theory to universals). For him, the Forms are transcendent of time and space, pure, and unchanging. They are the ultimate reality of the universe and provide a pure, abstract model for all manifestations of each Form in the physical world, which are called particulars.
This concept first appears in the Meno where Plato speaks about virtue and the Form of Virtue but is not explained until the Republic where he lays out exactly what particulars and forms are and how the former participates in the latter (Republic Book V 476a). One of Plato’s arguments for the existence of forms is also tied into the ‘proof’ for the immortality of the soul in his Argument from Knowledge: (1) In the Phaedo, he claims since there is such a thing as knowledge, (2) we acquire that knowledge with our souls through reasoning.
(3) However, our bodies and senses are obstacles to acquiring knowledge via incorrect reasoning, perception, and bodily drives. We would have to separate ourselves or our souls from our bodies in order to acquire the knowledge. (4) The objects of knowledge are the forms, so (5) the only way we’ll grasp forms completely and have pure knowledge is if we escape the body and grasp them with the soul alone. Therefore, (6) we either can never attain knowledge or can only do so after death (having been disembodied).
(1+6) And since knowledge does exist, the Phaedo concludes that we will obtain true knowledge after death because our souls are immortal. However, I would like to make an argument for a technical flaw in his theory. If (1) there is such a thing as knowledge, and (6) we can only grasp true knowledge after death when we have separated from our bodies, than how can it be possible for us to know that knowledge really exists? By this logic, I could argue that, since heaven is a place, and I can’t experience heaven until I have left the earth and died, than heaven must be where I go when I die.
However, how can we possible know about the existence of heaven (or knowledge) while we are on earth if its existence is only proven after we have died? Plato provides an additional explanation which states that since there is such a thing as knowledge that is eternal and unchanging, A Priori knowledge, that which is known, must likewise be eternal and unchanging. A Priori knowledge is not contingent upon things in the physical world and therefore does not change. An example of this would be the fact that 2+2 always equals 4.
Because that which is known must also be eternal and unchanging (forms) forms must exist. Plato also makes an argument that true knowledge can only come from the understanding of forms. Understanding of particulars can only be opinion because facts about particulars are contingent upon the physical world, which is constantly changing (Republic Book V 477a). While this explanation provides a way for us to have knowledge about things on earth (because A Priori knowledge is unchanging and not reliant on the physical world), I feel like he has only dug himself into a further hole with his own logic.
Again, if we can have knowledge that 2+2=4 without having died, than we do not need to release ourselves from our bodies in order to commune with or grasp the forms. Aristotle criticized these faults and holes in Plato’s logic and made attempts to fill them with what he believed was a better fit to what he deemed true. A universal for Aristotle is not something separate from the particulars, but rather it is something that is shared by any number of particulars. This could be heaviness or “table-ness”.
Aristotle also says that the universal does not come into physical existence. It can only exist in a particular because all substances, according to Aristotle, spoken of as compounds perish at some point (Metaphysics Book VII Section 15). Universals cannot and do not perish because they never come into existence other than within a particular. Universals cannot exist without particulars. Another point that Aristotle makes about universals is that the scientific knowledge we have can only be about universals (Posterior Analytics Book II Section 19).
This is similar to what Plato said in his Argument from Knowledge: A Priori knowledge, which both Plato and Aristotle believe to be the only true knowledge, is unchanging and eternal. This is the scientific knowledge we have about the world. Aristotle says that we cannot have scientific knowledge about individual particulars, but only about universals. We can only have scientific (A Priori) knowledge about something that is unchanging and non-contingent upon the physical world. Particulars in the physical world are constantly changing and ending.
Therefore, we can’t know why a particular is the way that it is (have knowledge about a particular) because it is always different than it was before and is finite. Universals, however, are unchanging and eternal so we can know why they are the way that they are and have unchanging, non-contingent, A Priori knowledge about them. Universals are truer and more real because they are pure, unchanging, and not contingent upon factors in the physical world. By this logic, we can still understand and grasp knowledge about the world without having to be disembodied.
We could not possibly know and understand universals simply from induction. Through induction we can gain the knowledge of first principles, which are a starting point for all deductions and demonstrations, but the knowledge of universals must be acquired through more scientific methods. Understanding universals cannot be done without much inquiry and lots of deduction because universals are the only true things. Particulars, because they change and are contingent upon physical factors in the world, cannot be truly known. We cannot have scientific knowledge about particulars.
We can only have true knowledge of universals, which are acquired through deduction after deduction, not induction. Plato says that we have innate knowledge of universals, but this cannot be true. Like Aristotle would say, the knowledge of universals is too perfect to possess without deduction and demonstration. In the physical world, atoms and molecules are constantly changing and reacting to the environment. They are contingent upon other chemical factors. They change all the time. Things in nature are constantly growing and dying, so how could we know concrete facts about something that does not remain the same even for a second?
What we can know, however is what is common between two things, such as what exactly about an armchair and a folding chair are the same. This is the universal. It can only exist within the particular and not outside of it because it is not a perfect or unusual particular. It is a quality, like “chair-ness” that is shared between two particulars. It is only manifested in these particulars and cannot be taken outside of them. This is due to the fact that if this concept were taken outside of the particulars it would simply become another particular, an unusual chair. This is what Aristotle was arguing against in Plato’s theory of forms.
While in contemporary philosophical and scientific thought, we have more information to work with than the ancient Greeks, the argument between Plato’s and Aristotle’s theories still have not been completely hashed out to acceptance or denial. They each have incredibly profound arguments for the existence of universals and what exactly the role of universals and particulars are in this world. While I disagree with the logic by which Plato arrives at his Argument for Knowledge, the ideas are no less compelling than Aristotle’s theory and still have great weight on contemporary discussions on the matters of learning and knowledge.