Comparison of Plato and Aristotle’s Philosophies


Plato and Aristotle are both great philosophers in their own regard. Both agree that the world has a purpose, and that it’s not just an accident. Both also hate materialists since in their (materialists’) interpretation of the world, value, choice, and freedom are not plausible outcomes, and so morality and rationality do not make sense. And both ask the same question, what does it take to be a good, moral person? Yet, even though Aristotle was a student of Plato, each philosopher develops his own view on things and a specific way of solving a particular problem.

For example, Plato and Aristotle have quite different views regarding life. Plato is dissatisfied with sense and desire, which are nothing to him except a shadow of reality – his aim of philosophy is to die away from these things. The real, on the other hand, is unchanging, static, eternal. He aims to grasp the Forms and to contemplate the True, the Good, and the Beautiful, and to remain caught up in contemplation of these things. Aristotle has no such discontents, however. He likes life in this world, even though it is not perfect. He does develop his own view of the divine and how it is related to the world, but sees no reason why one would be driven to flee from life in the world. The various animals he studies are real things; philosophy to him is not to run away from them, but a way of comprehending them.

Plato is committed to the idea that reality is ultimately rational. His Forms are definite realities made up and bonded together in perfectly rational ways, and together they make a perfectly systematic whole. For him, mathematics seems to embody the ideal of knowledge and reason is the only way to discover truth. But not even reason is sufficient – far enough up the hierarchy of Forms one has to “see” the truth with the “mind’s eye.” Plato is unable to describe what must be seen, so he explains what we cannot see through language using Myths of the Sun and the Cave. Aristotle has no problem expressing himself through language, however. He believes language is capable of expressing the truth of things, since that truth concerns the sensible world, and our view of it (the world) begins with our senses, hearing, touching, seeing, etc. Although the senses themselves are not sufficient to lead to knowledge, they are the only reliable entities through which we can pursue it.

The two philosophers also differ on what human nature is. Plato is convinced that the real person is the soul, not the body. Souls that inhabit our bodies are there, but are not dependent on us for their existence. They have knowledge of the Forms before we are even born and by being virtuous we can enjoy unity with the Forms after death. Aristotle’s main theme on humans is simple – man is a rational animal. There is no separate soul from man; a person has a soul that is special, but a person is still one unified creature.

Plato seems to be very concerned about relativism and skepticism and devotes a lot of writing to proving those beliefs wrong. He thinks that skepticism and relativism killed Socrates, not the members of the Athenian jury. The views they have come to hold – that every opinion is as good as another’s, and that if one thinks something is good for them really is good for them – makes the case of Athens thinking it is right to condemn Socrates right for Athens. Plato knows condemning Socrates is wrong; so he knows that there must be standards that are more conventional. The Forms, the dialectic about Justice, and the subordination of everything else to the Form of the Good all reflect his view against relativism and skepticism. For Aristotle, though, such a problem never existed. One reason why could be because Plato did such a good job in proving the relativists and skeptics incorrect, so there is no reason for it to be done again. He sees the foolishness in believing that anyone’s opinion is equally accepted. So as a biologist he performs research and writes up the results, which constitutes knowledge in the sensory world. His only problem is to analyze the processes by which we attain knowledge and to set out the basic features of the realities disclosed.

On ethics Plato thinks that we are able to obtain the same kind of certainty in rules of behavior as with mathematics. According to him the ultimate vision of the Form of the Good will provide a single standard for deciding practical questions. Unfortunately only the few individuals who can make the hard journey through the Cave will be able to give a solution for all questions of value. Aristotle does not have the same view – according to him, we should not ask for more certainty than the subject matter allows. A normal person is able to make good decisions and to live a good life; one need not be an expert in ethical knowledge to practice it.

The preceding paragraphs show that although the two philosophers are quite similar in the problems they deal with, they go about doing it in a very separate and distinguished manner. Most of Plato’s philosophy is centered on the Forms, which is his solution for pretty much everything. Aristotle, on the other hand, does not have one unifying solution. He prefers to tackle each problem separately, work it out as best as he can, and give an answer. And yet both of them deserve utmost credit for at least one thing: making people think. That is very important, especially in today’s society where people prefer to reason things out with guns and fighting instead of thinking of a solution.

(c. 428–c. 348 BCE) and Aristotle (384–322 BCE) are generally regarded as the two greatest figures of Western philosophy. For some 20 years Aristotle was Plato’s student and colleague at the Academy in Athens, an institution for philosophical, scientific, and mathematical research and teaching founded by Plato in the 380s. Although Aristotle revered his teacher, his philosophy eventually departed from Plato’s in important respects. Aristotle also investigated areas of philosophy and fields of science that Plato did not seriously consider. According to a conventional view, Plato’s philosophy is abstract and utopian, whereas Aristotle’s is empirical, practical, and commonsensical. Such contrasts are famously suggested in the fresco School of Athens (1510–11) by the Italian Renaissance painter Raphael, which depicts Plato and Aristotle together in conversation, surrounded by philosophers, scientists, and artists of earlier and later ages. Plato, holding a copy of his dialogue Timeo (Timaeus), points upward to the heavens; Aristotle, holding his Etica (Ethics), points outward to the world.
Although this view is generally accurate, it is not very illuminating, and it obscures what Plato and Aristotle have in common and the continuities between them, suggesting wrongly that their philosophies are polar opposites.
So how exactly does Plato’s philosophy differ from Aristotle’s? Here are three main differences.

Forms. The most fundamental difference between Plato and Aristotle concerns their theories of forms. (When used to refer to forms as Plato conceived them, the term “Form” is conventionally capitalized, as are the names of individual Platonic Forms. The term is lowercased when used to refer to forms as Aristotle conceived them.) For Plato, the Forms are perfect exemplars, or ideal types, of the properties and kinds that are found in the world. Corresponding to every such property or kind is a Form that is its perfect exemplar or ideal type. Thus the properties “beautiful” and “black” correspond to the Forms the Beautiful and the Black; the kinds “horse” and “triangle” correspond to the Forms the Horse and the Triangle; and so on.

A thing has the properties it has, or belongs to the kind it belongs to, because it “participates” in the Forms that correspond to those properties or kinds. A thing is a beautiful black horse because it participates in the Beautiful, the Black, and the Horse; a thing is a large red triangle because it participates in the Large, the Red, and the Triangle; a person is courageous and generous because he or she participates in the Forms of Courage and Generosity; and so on.

For Plato, Forms are abstract objects, existing completely outside space and time. Thus they are knowable only through the mind, not through sense experience. Moreover, because they are changeless, the Forms possess a higher degree of reality than do things in the world, which are changeable and always coming into or going out of existence. The task of philosophy, for Plato, is to discover through reason (“dialectic”) the nature of the Forms, the only true reality, and their interrelations, culminating in an understanding of the most fundamental Form, the Good or the One.

Aristotle rejected Plato’s theory of Forms but not the notion of form itself. For Aristotle, forms do not exist independently of things—every form is the form of some thing. A “substantial” form is a kind that is attributed to a thing, without which that thing would be of a different kind or would cease to exist altogether. “Black Beauty is a horse” attributes a substantial form, horse, to a certain thing, the animal Black Beauty, and without that form Black Beauty would not exist. Unlike substantial forms, “accidental” forms may be lost or gained by a thing without changing its essential nature. “Black Beauty is black” attributes an accidental form, blackness, to a certain animal, who could change color (someone might paint him) without ceasing to be himself.

Substantial and accidental forms are not created, but neither are they eternal. They are introduced into a thing when it is made, or they may be acquired later, as in the case of some accidental forms.

Ethics. For both Plato and Aristotle, as for most ancient ethicists, the central problem of ethics was the achievement of happiness. By “happiness” (the usual English translation of the Greek term eudaimonia), they did not mean a pleasant state of mind but rather a good human life, or a life of human flourishing. The means by which happiness was acquired was through virtue. Thus ancient ethicists typically addressed themselves to three related questions: (1) What does a good or flourishing human life consist of?, (2) What virtues are necessary to achieve it?, and (3) How does one acquire those virtues?

Plato’s early dialogues encompass explorations of the nature of various conventional virtues, such as courage, piety, and temperance, as well as more general questions, such as whether virtue can be taught. Socrates (Plato’s teacher) is portrayed in conversation with presumed experts and the occasional celebrity; invariably, Socrates exposes their definitions as inadequate. Although Socrates does not offer his own definitions, claiming to be ignorant, he suggests that virtue is a kind of knowledge, and that virtuous action (or the desire to act virtuously) follows necessarily from having such knowledge—a view held by the historical Socrates, according to Aristotle.

In Plato’s later dialogue Republic, which is understood to convey his own views, the character Socrates develops a theory of “justice” as a condition of the soul. As described in that work, the just or completely virtuous person is the one whose soul is in harmony, because each of its three parts—Reason, Spirit, and Appetite—desires what is good and proper for it and acts within proper limits. In particular, Reason understands and desires the good of the individual (the human good) and the Good in general. Such understanding of the Form of the Good, however, can be acquired only through years of training in dialectic and other disciplines, an educational program that the Republic also describes. Ultimately, only philosophers can be completely virtuous.

Characteristically, for Aristotle, happiness is not merely a condition of the soul but a kind of right activity. The good human life, he held, must consist primarily of whatever activity is characteristically human, and that is reasoning. The good life is therefore the rational activity of the soul, as guided by the virtues. Aristotle recognized both intellectual virtues, chiefly wisdom and understanding, and practical or moral virtues, including courage and temperance. The latter kinds of virtue typically can be conceived as a mean between two extremes (a temperate person avoids eating or drinking too much but also eating or drinking too little). In his Nicomachean Ethics, Aristotle held that happiness is the practice of philosophical contemplation in a person who has cultivated all of the intellectual and moral virtues over much of a lifetime. In the Eudemian Ethics, happiness is the exercise of the moral virtues specifically in the political realm, though again the other intellectual and moral virtues are presupposed.

Politics. The account of justice presented in Plato’s Republic is not only a theory of virtue but also a theory of politics. Indeed, the character Socrates there develops a theory of political justice as a means of advancing the ethical discussion, drawing an analogy between the three parts of the soul—Reason, Spirit, and Appetite—and the three classes of an ideal state (i.e., city-state)—Rulers, Soldiers, and Producers (e.g., artisans and farmers). In the just state as in the just individual, the three parts perform the functions proper to them and in harmony with the other parts. In particular, the Rulers understand not only the good of the state but, necessarily, the Good itself, the result of years of rigorous training to prepare them for their leadership role. Plato envisioned that the Rulers would live simply and communally, having no private property and even sharing sexual partners (notably, the rulers would include women). All children born from the Rulers and the other classes would be tested, those showing the most ability and virtue being admitted to training for rulership.

The political theory of Plato’s Republic is notorious for its assertion that only philosophers should rule and for its hostility toward democracy, or rule by the many. In the latter respect it broadly reflects the views of the historical Socrates, whose criticisms of the democracy of Athens may have played a role in his trial and execution for impiety and other crimes in 399. In one of his last works, the Laws, Plato outlined in great detail a mixed constitution incorporating elements of both monarchy and democracy. Scholars are divided over the question of whether the Laws indicates that Plato changed his mind about the value of democracy or was simply making practical concessions in light of the limitations of human nature. According to the latter view, the state of the Republic remained Plato’s ideal, or utopia, while that of the Laws represented the best that could be achieved in realistic circumstances, according to him.

In political theory, Aristotle is famous for observing that “man is a political animal,” meaning that human beings naturally form political communities. Indeed, it is impossible for human beings to thrive outside a community, and the basic purpose of communities is to promote human flourishing. Aristotle is also known for having devised a classification of forms of government and for introducing an unusual definition of democracy that was never widely accepted.

According to Aristotle, states may be classified according to the number of their rulers and the interests in which they govern. Rule by one person in the interest of all is monarchy; rule by one person in his own interest is tyranny. Rule by a minority in the interest of all is aristocracy; rule by a minority in the interest of itself is oligarchy. Rule by a majority in the interest of all is “polity”; rule by a majority in its own interest—i.e., mob rule—is “democracy.” In theory, the best form of government is monarchy, and the next best is aristocracy. However, because monarchy and aristocracy frequently devolve into tyranny and oligarchy, respectively, in practice the best form is polity.