When Plato writes that "there is an old quarrel between philosophy and poetry," it accentuates that a difference in world view that exists between both. For Plato, this difference in cosmology is where a clash lies. Both view consciousness differently. Through Socrates, Plato argues that the poet like Homer does not fully articulate a proper basis for being in the world. Socrates is through in his rejection of a tragic condition of man. For Socrates, human essence should be focused on living life in accordance to the ideal, or the form. This is where consciousness is driven and human efforts to appropriate the good, the true, and the beautiful as part of their being in the world removes any notion of tragedy. It is in this light where Socratic ideas lead to a comic and unifying form of being. Where Plato sees Homer as wrong is because of the tragic conception of human consciousness that is such a part of his work. While Socrates reject tragic conditions, Homer sees nothing but tragedy. The "city of words" is not one predicated upon pursuit of the forms. The focus of the Socratic logic is to suggest that one's world view can be comic and unifying when recognition of the forms is part of one's being in the world. When Plato suggests that Homer is "the leader" of tragedy, it is meant to criticize poetry as a "false" depiction of consciousness.
The implications of this difference in perception of significant. Socrates suggests that part of the flaw in the tragedy of the poets is that it invalidates pursuit of honorable notions of the good, namely, the forms. If individuals are mired in tragedy, then there is little incentive to embrace the pursuit of the forms. Socrates faults poetry for suggesting that “many happy men are unjust, and many wretched ones just, and that doing injustice is profitable if one gets away with it, but justice is someone else's good and one's own loss.” This becomes another one of the critical points against poetry. Plato asserts that the rigor in the polemics of philosophy make it intrinsically superior to poetry, something predisposed to embracing a tragic condition of being in the world.
It is interesting to take a small step back and evaluate the parameters of this debate. Indeed, the fundamental rejection of poetry on the grounds that it advocates a sense of tragedy could be seen as valid. The poet certainly is able to embrace tragedy. Few did it better than Homer. Yet, I would suggest that part of what caused Plato to suggest that there exists a quarrel between both expressions existed in how poetry was seen as more socially accepted than philosophy. Plato suggests that this is the root of his critique: "...praisers of Homer who say that this poet educated Greece, and that in the management and education of human affairs it is worthwhile to take him up for study and for living, by arranging one's whole life according to this poet.” In reality, I think that Plato might be challenged in seeing how both philosophy and poetry are marginalized today. Both do not enjoy the status of "management and education of human affairs." Both forms of discourse are not dominant in the modern setting. One is not preferred over the other. A case can be made to show that both are maligned, and both sets of world views are denied. Neither one exerts more power over the other. In the modern setting, one might see Plato's objection as limited in suggesting a clash of values.