Philosophical Arguments Of Plato And Aristotle

This paper tends to use known facts and dialogues as the starting point from which to draw inferences and solutions based on the philosophical arguments of Plato and Aristotle.

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The basic notions of Aristotle’s philosophy of nature can be understood from his analysis of change. When Aristotle undertook to explain how it is that things change, a fact apparent to anyone, he had first to confront the seemingly iron-clad logic of Parmenides.

According to Parmenides “All change is mere appearance; reality is One, and this One, which only is, is unchanging.” Parmenides had argued that there are only two alternatives for anything, being and non-being. No new being can come from non-being since “nothing comes from nothing.” Nor can new being come from being since what has being, already is and does not begin to be: “being cannot come from being since it is already.”

The advance that Aristotle made over Parmenides consists in seeing that, although it is true that “nothing can come from nothing,” it is not entirely true that “being cannot come from being.” One must distinguish being-in-act from being-in-potency. While it is true that from being-in-act, being-in-act cannot come since it would already be. The alternative from which being can come is not non-being, but being-in-potency. From being-in- potency there can come being-in-act.

Potency, in this case, is defined as the capacity for growth and development.


In his analysis of change, Aristotle discovered that every change implies duality. It implies a subject in potency which, by the action of some agent, pases into act, i.e. receives some new perfection or actuality. Motion presupposes the acquisition of something and the corruption of something else. The subject of change is what stays the same through the change. However, through the change, it acquires something new and loses what it previously had. Motion implies a passive principle and an active principle, intrinsic to the thing that changes. This he described as accidental change.

Thus, there are three principles necessary for change to take place. There must be something new that comes to be, something old that passes away, and something that stays the same throughout. In the Aristotelian tradition, these principles receive the names form, privation and matter.

Form is what comes to be

Privation is what passes away

And matter is what stays the same throughout the change.

In the case of a statue, the shape of the sculpture, Michelangelo’s “David” for instance, is the form that comes to be when a formless block of marble becomes a statue. The formlessness of the block is itself the privation of the statue shape, and the potency for the statue shape. The marble, first in block shape, later in “David” shape, is what stays the same throughout the change. The case of the coming to be of a statue is an instance of an accidental change; what changes are the accidents of the marble. What stays the same is the substance of the marble.


For Aristotle, motion is the technical name for changes in accidents. There are three kinds of motion for Aristotle: a change in quality (which he calls alteration), a change in quantity, size (called growth or diminution), and a change in place (called local motion). In all cases, motion, as such, is defined as the act of a being in potency insofar as it is in potency. Motion is the process that a substance goes through in which it loses one accidental form or actuality and gains another.

Aristotle discovered these principles of nature (matter, form and privation) by analyzing accidental changes. He found that they could also explain the more fundamental kinds of changes, changes that involve the passing away and coming to be of substances.

Example; If one admits that sodium and chlorine are different substances (and they certainly appear different – one is a white metal, the other a green gas), and that they are each different from salt (also apparently so), then one can see that the change from sodium and chlorine to Sodium chloride (salt) is a substantial change.


Plato argued that both the material objects perceived and the individual perceiving them are constantly changing; but, since knowledge must be concerned only with unchangeable and universal objects, knowledge and perception are fundamentally different.

In his theory of forms Plato meant to solve the ethical and intellectual problems as well as that of change and permanence: How can the world appear to be both permanent and changing? The world we perceive through the senses seems to be always changing. The world that we perceive through the mind, using our concepts, seems to be permanent and unchanging. Which is most real and why does it appear both ways? These are the arguments Plato sought to solve.

The general structure of the solution: Plato splits up existence into two realms: the material realm and the transcendent realm of forms.

Humans have access to the realm of forms through the mind, through reason, given Plato’s theory of the subdivisions of the human soul. This gives them access to an unchanging world, invulnerable to the pains and changes of the material world. By detaching ourselves from the material world and our bodies and developing our ability to concern ourselves with the forms, we find a value which is not open to change or disintegration. This solves the first, ethical, problem.

Splitting existence up into two realms also solves the problem of permanence and change. We perceive a different world, with different objects, through our mind than we do through the senses. It is the material world, perceived through the senses, that is changing. It is the realm of forms, perceived through the mind, that is permanent and immutable. It is this world that is more real; the world of change is merely an imperfect image of this world.

A form- This is an abstract property or quality. Take any property of an object; separate it from that object and consider it by itself, and you are contemplating a form.

Plato’s characterization of forms to explain permanence and change:

The forms are transcendent- This means that they do not exist in space and time. A material object, for instance a basketball, exists at a particular place at a particular time. A form, the roundness, does not exist at any place or time.

Therefore a form such as roundness will never change; it does not even exist in time. It is the same at all times or places in which it might be instantiated.

The forms are also pure- This means that they are pure properties separated from all other properties. A material object, such as a basketball, has many properties: roundness, ballness, orangeness, elasticity, etc. These are all put together to make up this individual basketball.

But the form, Roundness, is just pure roundness, without any other properties mixed in.

In virtue of the fact that all objects in this world are copies of the forms, the forms are the causes of all that exists in this world. In general, whenever you want to explain why something is the way that it is, you point to some properties that the object has. That is, you explain what forms the object is a copy of. The forms are causes in two closely related ways:

The forms are the causes of all our knowledge of all objects. The forms contribute all order and intelligibility to objects. Since we can only know something insofar as it has some order or form, the forms are the source of the intelligibility of all material objects.

The forms are also the cause of the existence of all objects. Things are only said to exist insofar as they have order or structure or form. Hence, the forms are the causes of the existence of all objects as well as of their intelligibility. Plato uses the sun metaphor to explain how the forms in general, and the form of the Good in particular, are causes in these two ways. Just as the sun gives light which allows us to see objects, the form of the Good provides order and intelligibility to allow us to know objects. Just as the sun provides the energy for the nourishment and growth of all living things, so the form of the Good provides the order and structure which is the source of the existence of all things.


In place of Plato’s doctrine of Ideas with a separate and eternal existence of their own, Aristotle proposed a group of universals that represent the common properties of any group of real objects. The universals, unlike Plato’s Ideas, have no existence outside of the objects they represent.

Aristotle sought a general combined principal approach, unlike Plato who insisted that the forms are the causes of the existence of all objects as well as of their intelligibility. Not implying that Plato was wrong but that Aristotle’s attribution of change to 3 principals seems to be logically acceptable i.e He did not separate Form from Privation nor from Matter. Form and matter, therefore, make up a substantial unity; one cannot have form without matter, nor matter without some form. But, one can still distinguish these principles, and also understand that these principles are real features of the things that exhibit them.

Aristotle thought that Plato’s theory of forms with its two separate realms failed to explain what it was meant to explain. That is, it failed to explain how there could be permanence and order in this world and how we could have objective knowledge of this world. By separating the realm of forms from the material realm, Plato made it impossible to explain how the realm of forms made objectivity and permanence possible in the material world. The objectivity and permanence of the realm of forms does not help to explain the material world because the connection between the two worlds is so hard to understand. Aristotle and the Aristotelian philosophers used logic to criticize the theory. Gail fine went to an extreme to say:

The theory of form is an unnecessary proposal. There is no need to split the world up into

two separate realms in order to explain objectivity and permanence in our experience.6

Aristotle elaborated this general criticism into two more particular objections:

1. The obscurity of the notion imitation:

According to Plato, material objects participate in or imitate the forms. It is in virtue of this relation to the realm of forms that material objects are knowable and have order. Yet, Aristotle argues, it is almost impossible to explain what exactly this participation or imitation is. The properties that the forms have (eternal, unchanging, transcendent, etc. ) are all incompatible with material objects. How, for example, can a white object be said to participate in or copy the form of whiteness? Is the form of whiteness white itself? How can there be whiteness without any thingwhich is white? What can a white object and the form of whiteness be said to have in common? It seems that the metaphor of imitation or participation seems to break down in these cases because of the special properties that Plato ascribes to the forms. The only link between the realm of forms and the material world, then, breaks down. The forms cannot explain anything in the material world.

2. The third man argument:

This argument was first given by Plato himself in his later dialogues. It is related to the first objection, but is a more technical way of getting at the main problem with the theory of forms. The resemblance between any two material objects is explained by Plato in terms of their joint participation in a common form. A red book and a red flower, for example, resemble each other in virtue of being copies of the form of redness. Because they are copies of this form, they also resemble the form. But this resemblance between the red object and the form of redness must also be explained in terms of another form. What form does a red object and the form of redness both copy to account for their similarity? Whenever someone proposes another form that two similar things copy, we can always ask them to explain the similarity between the form and the objects. This will always require another form. The notion of imitation or copying used in the theory of forms, then, runs into logical difficulties. The theory of forms really explains nothing about the similarity of objects; another form is always needed beyond the one proposed. Thus to explain the similarity between a man and the form of man, one needs a third form of man, and this always requires another form. The explanation of the original similarity is never given; it is only put off to the next level.

This criticism paved the way for further criticism. As there was no logical connection between the transcendent forms and the material world, so many critics raised a question about the epistemological dimensions of this theory. Plato was of the view that real knowledge was knowledge of form and the ideal destiny of a man was to reach the realm of forms. But he didn’t mentioned how to reach that realm. As it was above this material world, so whether there was a way to reach that realm in one’s life or only death could take a man in that ideal realm. The idea of forms was very abstract and it wasn’t clear enough to be accepted, un criticized.

Plato didn’t write much about his theory of forms and most of the written work was also not preserved. Pheodo was the first book to have this theory and later on in republic he explained it a bit. But this explanation was too little to make the theory clear. So the explanation was mostly rendered by the commentators of the theory. This became the major source of criticism on this theory.


The criticism of Aristotle and Aristotelian philosophers, on this theory, is mostly of explanatory type. Had Plato written more or his books had been preserved, there might not have been that strong criticism on this theory. Even then the theory was powerful enough to split the philosophy and philosophers in two parts. Though a group of philosophers don’t agree with the content of the theory but even they accept that this theory provided human beings with s new way to think and perceive the universe.