Plato’s theory on poetry is formed on the basis of mimesis. He states poetry is thrice removed from reality and dwells in the realm of appearances. In his text The Republic Plato writes “All poetical imitations are ruinous to the understanding of the hearers, unless as an antidote they possess the knowledge of the true nature of the original.” The Modes of being Plato is inferring is to his notion of Ideas. For Plato Ideas are universal and Knowing is particular. Thus, Plato’s foundation of categorizing poetry is in the realm of the particular, which is the realm of appearances. Hence, poetry is a mimetic practice.
There are a few weaknesses in Plato’s argument. The main weakness deals with the form of this text. First, this text is coming to me as a translation from a distant language. In translation a text loses certain nuances and subtleties.
The next weakness of form deals with the purpose of The Republic. The purpose of this text is to teach those in power how to rule; hence, its title The Republic. It may be that this is a metaphor for how society should act. However, it lacks to be a criticism about art since its defined purpose and motives are other than the basis of creating art. Albeit, this text is stating art should make its audience cultured, and to engender culture should lead one to create art. Beyond the fact that culture is a relative term defined by those in a position to have their definition be the dominant opinion in society, Plato goes about in rather lengthy and circuitous manner criticizing art as something that should engender its audience to being cultured.
Another weakness in the form concerns how the arguments are delivered. Other than Socrates the interlocutors don’t offer opposing opinions for the arguments to be expanded and debated in any depth beyond the dominant one expressed by Socrates. At one point Glaucon indicates that he would be too shy to explain any views he did have in front of Socrates.
Another criticism I have about Plato’s The Republic. Plato comments that there is an original bed and an idea of a bed. The maker of the bed copies the idea of the bed. I suppose this holds true for a step ladder as well. However, Plato is talking about a thing first being wholly original unto itself, but it’s not about a thing.
While making me a bed the bed maker may be making me a step ladder if I use my bed to boost me up to elevate my reach in order to change a light bulb. Now am I’m standing on the idea of a bed or am I standing on the idea of a ridiculous step ladder? Even yet what if I’m standing on a bed using it as a step ladder while at the same time someone else is lying asleep on the bed? What is it at that moment? Is it the Idea of a bed or the Idea of a step ladder? A bed could be used for many other purposes other than reclining in and sleeping. These are just a couple of thoughts that ran through my head as I was reading the text. 
Both the bed and the step ladder are essentially serving the purpose and idea, but as you can see, one clearly isn't the other.
