Plato’s Theory of Forms in the Phaedo and Aristotle’s Theory of Substance in the Categories





Plato’s Theory of Forms in the Phaedo and Aristotle’s Theory of Substance in the Categories

The theory forms by Plato is an argument that is presented in different types of his works, including the Phaedo. Plato spent close to forty years developing this theory, which has immensely contributed to Western philosophy, and aroused different reactions among various scholars. In this theory, Plato asserts that the physical world, as we see it, with its imperfections, is a representation of another invisible perfect and ideal world. Therefore, the things and experiences in this world are not all there is. However, humans cannot experience the perfect world in this physical world, unless they leave the physical world (Dancy 4).

On the other hand, Plato’s student, Aristotle, developed his theory of substances, which featured in his books Categories and Metaphysics Z. In this theory, Aristotle considered substances, and not accidents, to be the real things in the world. Substances include things such as a dog, a planet, a rock, and people, among other things. Substances are important because they are the first to exist before accidents, and accidents cannot happen without substances. He categorizes substances as primary and secondary substances. Between Plato’s theory of forms and Aristotle’s theory of substances, the latter is more convincing, as it bases on science, therefore helping us integrate our basic understanding of the world and the scientific facts about the world (Spellman 12).

Plato in his theory of forms believed that although a person’s life and their experiences therein vary from time to time, are definite, and realistic, it is not the same case with their ideal forms, which he believed were static and real. To him, forms were universal and comprised the real world. The visible ones are just particulars, a mimicry of the real things.  He believed that people perceive reality differently from what it really is. Plato believed that what people think is reality, is not, and is the opposite of reality. Nonetheless, Plato in this theory emphasized a form of recognition, rather than cognition (Dancy 18).

Plato believed that, beyond this physical world, there existed a perfect and ideal world. The physical world human beings live in today is characterized by different imperfections, unevenness, and impurities that have been copied from the ideal perfect world beyond the physical world. This is the case because our physical world, apes the real forms of the ideal perfect world, in a disorderly manner. However, Plato thought that there exists a connection between our physical world, and the realms of forms. From this relationship, the mortal beings come to understand forms and the order of life (Dancy 34).

The theory of substance in Aristotle’s Categories categorized substances into two groups, the primary substances and the secondary substances.  Primary substances are absolute objects, which can be distinguished from other things, including secondary substances, and other predicables. Aristotle’s Categories bases on the explanation of meaning of substances, so that a person hearing it for the first time can be in position to understand the concept. In addition, it presents substances as a primitive concept, which people have little knowledge about (Spellman 22).

The theory of substance by Aristotle was developed as a way of counteracting Plato’s theory of forms. Aristotle considered a substance to be a complex and integrated whereby there is raw matter, as well as a compound of the substance. He also explained some traits of a substance, which are important, as they define it. First, he believed that substances do not allow for levels or degrees. This therefore, implies that something cannot be too much of a substance or too little of a substance. Additionally, Aristotle believed that substances could allow for contraries, or opposites. In this case, a substance may have two different opposing sides. For instance, a child might at one point fall sick, and they may be well at another point. Therefore, sicknesses and good health, are opposing sides, that characterize children in this case, who are substances. Aristotle also pointed out that since substances have contraries, they also have the capability of enduring over time. This means that substances can survive change in different periods (Spellman 8).

In Aristotle’s theory of substance, he differs with Plato’s views about the relationships between the real forms and the ideal forms. According to Aristotle, no one has the capability of having the knowledge about what kind of relationship exists between the two forms, or how the two forms interact. Aristotle in his theory goes ahead to argue that the real and ideal forms are pure, everlasting, and unchanging, therefore, there is no way these can relate or compare to the material objects of forms in the physical world, which are full of imperfections in their physical state. Aristotle in his theory of substance, however, seems to agree with Plato on the fact that human beings develop some type of biological and scientific wisdom of a primary substance, which can either be rock, animal, or plant, but only when there is knowledge of its causes (Spellman 35).

Plato in his theory of forms believed that human beings had the capability to rise above their physical world, and that is the time when they would have the opportunity to understand the other form in the invisible world, which are ideal and real. This could probably happen when a person dies, and is out of the physical world, as Plato did not specify whether this would happen during a person’s lifetime or not. On the contrary, Aristotle believed that all the forms were here in the physical world, and that one did not have to exit the physical world in order to experience a different type of form. However, one just needed to adopt a scientific method in order to apprehend the ideal perfect form (Voegelin and Sandoz 32).

While Plato believed that the physical world is a representation of the real perfect form, and that what we perceive today as real is just a mimicry of the real things, but in an imperfect state, Aristotle thought differently. He believed that the physical world is real, as we perceive it, and has real things. Aristotle was knowledgeable in the physical and biological phenomenon, having been a teacher of this. He therefore, understood that the physical world comprises multiple forms, although not all of these were perfect. However, he believed that human beings were capable of identifying different forms by using their natural senses (Spellman 2-3).

Plato’s theory of forms is not capable of explaining our physical world, how it came into existence, and the order of things in this world. Another limitation of Plato’s theory of forms draws from his idea of resemblance of two objects. Plato believed that two objects might resemble each other because they all are a part of the common form. For instance, a white dog and a white book are similar in the form of “black.” However, according to Plato, these two must also be explained as similar in another form. This assumption makes this theory lose its reliability, as it fails to explain how this happens (Spellman 6).

In the Phaedo and other of his works with the theory of forms, Plato did not give a detailed explanation of his ideas, thus different scholars have ended up interpreting Plato’s thoughts differently, making this theory unreliable. Plato himself also criticized this theory in his other works. In addition, Aristotle too, and other philosopher then criticized this theory and termed it as ineffective. On the other side, Aristotle in his theory of substances was wise to give detailed meaning of every thought or idea he used in this theory. Since Aristotle was knowledgeable in Biology, he used part of this knowledge to build on his facts in the theory, making the theory more reliable, as it is based on scientific facts, which cannot be challenged. Unlike Plato’s theory, Aristotle’s theory helps us have a clear understanding of the world around us. This theory makes us see things the way they are, as absolute entities, unlike Pluto’s theory, where things are considered not what they really are, but a reflection of other things. Therefore, Plato does not explain what exactly things are (Voegelin and Sandoz 12).

Aristotle in his theory also makes people put their scientific knowledge, as well as their common knowledge to test.  For instance, when scientists talk about how light waves travel, it seems to be complex. However, if people understand that light waves are just things like puddles, then it is easier for them to explain light waves in relation to puddles, thus making them understand a new concept from a different concept they knew before. Rejecting the theory of substance is therefore, likened to rejecting common sense. This is because different things in the world are substances, made up of particles and atoms (Spellman 38).

Conclusively, Plato in his theory of form is seen as being subjective, therefore unreliable. This is because he emphasizes his idea that all things in the world cannot be known nor understood, since the real forms are not in this imperfect physical world, but exist in an invisible perfect eternal world. This greatly contrasts with Aristotle’s view that the physical world can be known and understood. Aristotle explained that human beings could gain this understanding of their physical world when they use their senses in the processes of observation and logic. It is therefore easier to relate with Aristotle’s opinions compared to Plato’s.  Plato’s theory is more of an imaginary theory, as it bases on imaginary facts. On the other hand, Aristotle in his theory, bases on scientific facts, which are easy to prove. Although Plato’s theory is unrealistic, it is still of importance in philosophy today, and cannot be rendered useless in philosophy. It continues to contribute to the important debate in philosophy about forms and their true meaning.





Works Cited

Dancy, R. M. Plato’s Introduction of Forms. London: Cambridge University Press, 2004

Spellman, Lynne. Substance and Separation in Aristotle. London: Cambridge University

Press, 2002.

Voegelin, Erick and Sandoz, Ellis. Order and History: Plato and Aristotle, Volume 16. New

York: University of Missouri Press, 2001.


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