Let's look at these three writers in chronological order. It would appear that Plato holds the view of poetry that most people today would have the least agreement with. To Plato, poetry is destructive to human happiness, or at least has the potential to be so, because it feeds the...
Let's look at these three writers in chronological order. It would appear that Plato holds the view of poetry that most people today would have the least agreement with. To Plato, poetry is destructive to human happiness, or at least has the potential to be so, because it feeds the passions instead of keeping them under control where they can do the least harm. To me, it is unclear if Plato is dismissing poetry per se or is saying only that the existing poetry he knows is bad, but that the art form can be improved in the future if it is made "useful" to humanity. He proposes that poets should be banished from his hypothetical ideal world, but that they might be allowed to return if they can prove themselves worthy of acceptance.
Aristotle's views are quite different. Poetry is a form of imitation (mimesis), but in mirroring the world it creates a kind of higher reality—not what is, but what might be. He also explicitly states, in almost the reverse of Plato's view, that art, or specifically tragedy, should evoke pity and fear in the spectator—in other words, to stimulate the passions, even negative passions, rather than to control them as Plato wished.
Fewer people are familiar with Longinus's views than with those of Plato and Aristotle. According to the Encyclopedia Britannica, Longinus is the first writer to ascribe "greatness in literature....to qualities innate in the writer rather than in the art." The interest in Longinus in the late eighteenth century was due to writers and philosophers of that period focusing their attention on the subject of "the sublime," which Longinus deals with in detail. Again, according to Britannica, Longinus "defines sublimity in literature as 'the echo of greatness of the spirit,' that is, the moral and imaginative power of the writer that pervades a work." Not only is the emphasis upon the writer different from that of Aristotle's approach, but the implied result in the art-work being created is also different. Aristotle defines tragedy as the highest form of poetry. In modern times, meaning from the Renaissance on, Aristotle's views have surely been the most influential of the three writers under discussion here. It is not surprising, because in some sense his views are the most "realistic" of the three, given that his definition of tragedy and of what makes a tragedy successful have been confirmed by the most moving dramatic works from antiquity through to our own time. By comparison, Longinus's aesthetics are more hypothetical in nature and more idealized in the sense that, at least in my view, they are less demonstrable than those of Aristotle. It's not surprising that Aristotle has been considered the "father of criticism" and has influenced literary specialists as diverse as Samuel Johnson and Ayn Rand, to name just two.