Per contra to Plato’s beliefs, Aristotle was an empiricist and had his own theory. Instead of splitting the world into two separate realms, Aristotle divides objects into two parts or aspects: form and matter. He argued that all objects are composed of a certain material arranged in a certain way. The material they are composed of is their matter. The way it is arranged is their form. An analogy for this comes with Lego. If you are given 100 Lego bricks (matter) you can make a house and then demolish it and rebuild it as a large wall (forms). The matter in both cases is the same but; the house and the wall have the matter arranged in different ways, so they have different forms. The house is still one material object but it has two different aspects to it. Aristotle believed that everything went by this theory. All objects have matter and the form is the way in which they are arranged. However the form can be seen as more important because it makes an object what it is. It is also the form of a thing that we know when we have knowledge of it. To know an object is to know their form. This is what makes them what they are. This can explain change, as change occurs when the same matter is arranged in different ways.
On the other hand, Plato uses the allegory of the cave to further push his point across. According to Plato, the world outside the cave represents the world of forms while the shadows on the wall represent objects in the physical world. The escape of the prisoner represents philosophical enlightenment and the realization that forms are the true reality. Most people are like the prisoners in the cave. They think the shadows are reality. Philosophers, though, are like the man who escapes the cave and sees the real world. They have true knowledge. They have conjecture, belief, thought and understanding.
Plato also uses perfection and perception as evidence for the forms. He argues for perfection that we have never seen a perfect circle, as it will always be slightly off. Yet we all know what a perfect circle would look like if it were to exist. This is where the ideal realm comes in. In order to know what the perfect circle is, we must have encountered it before, perhaps in the ideal realm. In which we encounter every archetype of knowledge in its perfect form. Plato also used perception saying that as humans we consider bot a pair of jeans and the sky blue. Yet they are most certainly no exactly the same color, and yet we somehow have a consensus of the basic form Blueness as it applies to them, once again knowledge that comes from the rationalist ideal realm.
Aristotle was not the only man who criticized Plato’s thinking. Plato had many of his own self-criticisms. He offered up the third man argument which was then further enhanced by Aristotle. The third man argument states that the resemblance between any two material objects is in terms of their joint participation in a common form. Blue jeans and the sky resemble each other as they are copies of the form of blue. But this resemblance between the blue object and the form of blueness must also be explained in terms of another form. However, what form does a blue object and the form of blueness both copy to cause their similarity. This leads to infinite regression. Another form will always be need beyond the one that was proposed, so the theory of the forms cannot explain the similarity of objects. Further difficulties drawn out of the form involve ideals, for example what is an ideal animal? Is there an ideal of every different type of animal or just one general ideal? Can there be ideals of bad things such as an ideal bomb or an ideal disease.
Overall, Plato’s claims that there are forms are backed up by evidences from the allegory of the cave and the divided line. However, to me, Aristotle’s theory of Corpuscularianism and how all form is shaped of matter which can be shaped in many different ways seems more assailable; also Plato himself recognized many chinks in his own armor with the third man argument, leading to the weakening of his original ideology.