Critically examine Plato’s Theory of the Forms

Philosophy A-level is a lot about explanation over argumentation but i would recommend some personal thought. Plato’s theory of the forms is demonstrative of his meta-physical thought and gives insight into his ontology, his epistemology and his pedagogy.
Plato states that a form is absolute immutable mould/ pattern for an example of something in the physical world. The easiest way to explain this is through an example. Think of all the circles you have ever seen. Was anyone of them a perfect circle? No, not one of them was absolutely perfect as real circles can never quite achieve every point on the circumference being the same distance away from the centre. Yet still, one understands what is meant by a ‘perfect circle’. Plato would say that the idea of a perfect circle is the form of the circle. In order to understand what a circle is you focus on the form of the circles. All physical circles are merely imperfect representations of this form. As a dualist, Plato draws a line not just between the mind and body but also between the physical world (The world of the particulars- that is imperfect and constantly changing) and the realm of the forms (The intelligible world - which is perfect and timeless). The forms exist independently from the physical world but are the binding force that allows us to identify an object. (E.g. a bedside table, a dinner table, a side table and a desk all different but the thing that makes them tables is the form of a table)
Plato’s allegory of the cave seeks to demonstrate all three aspects of his meta-physics. His ontology: The physical world is represented by the cave itself and the outside world is the realm of the form. The fire in the cave represents the physical sun whilst the sun in the allegory represents the form of the good and the stars represent mathematical truths. As the man escapes from the cave he goes from Knowing the physical objects (Shadows on the wall) to knowing forms of the outside world. The allegory of the cave also presents Plato's epistemology. The man in the cave goes from being able to comprehend images and shadows displayed on the world (Illusion due to belief) to understanding gaining pure though allowing him to comprehend to forms – the objects in the outside world. As he ascends through the cave he ascends through the levels of reasoning as well as the levels of apprehension.
Finally, the theory of the cave represents Plato’s Pedagogy. Appreciating the richness of the world around him and pities his fellow prisoners so goes back to save them and drag them out of the cave even though they initially do not like change. Plato believes it is the duty of the philosopher, the enlightened one, to help others and enlighten them no matter what. (This is reminiscent of the fact that even after Socrates was killed for ‘Corrupting the youth’ Plato continued to teach)
The biggest criticism came however from his own student, Aristotle. 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.
The third man argument: This argument, first created by Plato himself in his later dialogues but mobilised by Aristotle to disprove his teacher states the resemblance between any two material objects as 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.