What is most real, universals or particulars? Plato and Aristotle gave diametrically opposed answers to this basic ontological question and proceeded to build their entire philosophies on the epistemological foundation of their individual answers. As a result, the question has been debated for centuries, some siding with Plato, others with Aristotle, and others still attempting to syncretize the ideas of each. For Plato, universal Forms or ideas are most real. They are imperceptible to the senses, but all that the senses perceive are, according to Plato, a mere shadow of the Forms. Plato sees the universal Forms as ontologically prior to the individual particulars perceived by the senses. His pupil Aristotle, on the other hand, not only affirms that individual particulars are ontologically prior to universals, but that without the individual particulars, there would be no universals. For Aristotle, individual particulars are most real.
In the Categories, Aristotle asserts that substances are, “in the truest and primary and most definite sense of the word” (2a11-13) individual particulars, such as this computer or that telephone (2a13). He asserts that only individual particulars are “neither predicable of a subject nor present in a subject” (2a12-13). Aristotle explains what being “predicable of” or “present in” a subject means in chapter two of the Categories. Being predicable of a subject or not, is simply a distinction between abstract universals and concrete particulars. The particular man, Codell Carter, is not predicable of any subject, but the universal “man” is predicable of Codell Carter. My particular copy of A First Course in Logic is not predicable of any subject, but the universal term “book” is predicable of my particular copy of A First Course in Logic. In other words, universal terms are predicable of subjects, while particular terms are not. As for being or not being in a subject, this refers to the possibility of independent existence. Aristotle describes a subject as that which is “incapable of existence apart from the said subject” (1a22-23). Thus, that which is not in a subject is the subject itself. Since the “Arctic Silver” color of my BMW, for example, cannot exist separately from my BMW, said color is in a subject. But the BMW itself is not in any subject, since the BMW is the subject (3a10-16). Thus, Aristotle distinguishes between attributes (which are present in a subject) and entities (which are not present in a subject) (Hsieh).
Plato considers universal Forms or ideas most real. In the Phaedo, Plato argues that abstract entities he calls “Forms” exist. He argues further that the Forms have always existed, never change and have no material existence. Plato argues that it would be a mistake to identify an “Arctic Silver” BMW with what “Arctic Silver” itself is, or a good predicate logic professor with what Good itself is. After all, Plato would argue, we might have two equally good predicate logic professors, like Codell Carter and Chris Foster, to choose from, and mistakenly think one of them isn’t good, but we would never mistake bad for good. The Forms are what Socrates is alluding to when he inquires into matters such as what every good professor has in common with every other good professor. The answer, according to Plato, is that each of these professors participates in the Form of Good. In other words, when we call an “Arctic Silver” BMW “Arctic Silver” and a good professor good, we are in a sense alluding to a standard of “Arctic Silverness” or goodness. The same thing happens when someone points at a picture of Dr. Jensen on the BYU Philosophy Department website and says it is Dr. Jensen. The pixels on the screen are not Dr. Jensen, but one says it is Dr. Jensen, because of the relationship it bears to a very different sort of entity. By the same token, Plato claims that the Forms are what many of our words refer to, even though they are very different sorts of entities from the ones perceived by our senses (Audi 710).
Returning to Aristotle’s definition of substance, we can now better understand the distinction he makes between primary and secondary substances. Primary substance ― being neither predicable of nor in a subject ― must refer to individual particulars, such as this printer and that chair (2a16-19). From this definition of primary substance, it follows that secondary substance must be the species and genera of primary substance, such as can be seen in the printer-peripheral and chair-furniture relationships (2a13-17). Aristotle’s notions of “predicable of a subject” and “in a subject” allow him to argue, against Plato, for the ontological primacy of individual particulars by merely stating “all the other things are either said of primary substances as subjects or in them as subjects” (2a33-34). “Animal” is predicated of the universal “man” only because animal is predicated of individual men. In like manner, attributes like color are in things generally only because they are in things individually. This leads Aristotle to the conclusion that “if [primary substance] did not exist, it would be impossible for anything else to exist” (2b4-6). Furthermore, Aristotle’s terms “primary substance” and “secondary substance” make it easier for him to demonstrate the plausibility of his conclusion regarding the ontological primacy of particulars. Using the term “substance” for both universals and particulars allows Aristotle to more directly compare them, and to argue that some universals are “nearer” to or more like particulars than others (2b7-8). Additionally, the term “secondary substance” may indicate a superficial concession to Plato, allowing Aristotle to then argue that even if we consider universals to be substance, they are still dependent upon individual particulars, or primary substance, for their existence. Therefore, individual particulars are more real than universals (Hsieh).
There are clear advantages to Aristotle’s view as opposed to Plato’s. Mainly, taking an empirical stance allows one to build a system of interrelated theories that, even though they may not necessarily be built on a firm foundation, can explain the world and what is in it in such a way as to allow one to act in it with confidence. The marvels of modern technology testify to this fact. However, we are left with the nagging question in our minds, “Is what I sense all there is?” Clearly Plato embraced an epistemological view that saw something beyond what the senses perceive in the background of the backdrop of what Aristotle calls reality, or the perceptible world. For many, myself included, there is a sense that there is more to the world than meets the eye. A clear advantage to Plato’s theory is that it explains, albeit mystically, many things that remain unexplained for Aristotle and his strictest followers.
Both Plato and Aristotle started, as all philosophers must, by making basic ontological and epistemological assumptions, or in other words, from first philosophy. Parting from these assumptions, they built theories upon theories on the foundations of their first philosophy. In the case of Plato and Aristotle, and for that matter, the entire Greek philosophical tradition, what they built has become a towering monolith. For better or for worse, all of Western civilization has developed in the shadow of this monolith. To this day, Aristotle’s first philosophy and the ideas that grew out of it – both his and those of his followers, voluntary or otherwise – have reigned supreme. Modern science and technology and all their marvels stem from them. All this because Aristotle parted ways with his master and embraced primary substance, or individual particulars, as most real.
Audi, Robert. The Cambridge Dictionary of Philosophy. New York: Cambridge University Press, 1995.
Hsieh, Diana. “The Substance of Early Aristotle.” Diana Mertz Hsieh: Overworked Graduate Student in Philosophy. 01 Oct 2002. 23 Feb 2008 <www.dianahsieh.com/docs/tsoea.pdf>.