To first step into the realm of their metaphysics, we need to shed the light on how each one of the philosophers chose to define the concept of imagination. Plato defined phantasia as a spectrum as opposed to a single idea: as was explained in his divided line, images were either shadows or phantasms, where ones were tied to scientific knowledge and conceptual thought, and the others to doxa. Either way, phantasia belongs to the lower realm of unreliability and change. Aristotle’s view, however, was much more concise, perhaps that’s another side of his rebellion against his master, as he simply believes that phantasia is the consciousness of a sensory content under conditions that are not conductive to reliable insight.From here we can add that they also disagreed on the role that the senses play. Plato, still influenced by Parmenides, thinks that only a god can reach the beautiful nakedness of the truth and that human can only strive to get as close to it as possible while knowing that they never will, as truth is only existing in the ideal world and never in the material one, whilst his disciple greatly emphasized on the sensory character of phantasia: meaning that truth exists in the one, unified, material world, and that perceived objects are the ones that could potentially turn into phantasms. This only gets clearer as Plato insists on the transcending character of ideas and, even after criticizing the Paramenidian doctrine in his later works, he still thinks that imagination is only a connection point between Ideas and material objects.
Not fond of the theory of ideal forms, Aristotle argues that knowledge and truth comes from within the human reasoning, and that phantasia is the mediator between perception and thought and though crucial to both, is completely separate from them. However, both philosophers agree upon the realness of phantasia and, after taking an interest in psychology, in categorizing it as a human state. In short, whilst Plato sees imagination as part of the lower soul, Aristotle considers it equal to other cognitive function.
This strikes the idea that either way, imagination helps the other cognitive abilities: it allows the thinker to bring ideas from the abstract world to the realm of tangible objects. As thoughts are generally turned into action, another important point is the way each philosopher relates phantasia (or deliberative phantasia as Aristotle calls it) to human actions. Plato, on the one hand, says phantasies have the power to give shape to future opinions, emphasizing on its role in regulating conduct. He even as far as to use it as a self-assessment tool in Timaeus, as in knowing the state of one’s phantasies as the several forms taken by our emotions in shaping our actions. Similarly enough, his disciple thinks that phantasia is expected to deliver the vital mental content for movement, more than perception and thought alone, thanks to its sensory contents. He also adds that since phantasies are vital to reasoning, it is as a consequence vital to decision making.
Yet another factor is tied to actions and imagination: pleasure as a challenge to moral conduct. If Plato took it upon himself to preach for suppressing the mortal part of a human being, and stated that phantasies can act as a moral compass, Aristotle was much more interested in the mechanism phantasies take in order to generate the pleasure one feels in the first place, and argued that imagination is in fact the vehicle for memory and expectation and thus pleasure.
Even though the two philosophers beliefs are fundamentally different, both contributed immensely to the modern school of thought, and both have receive harsh criticisms; Plato for example, can be seen as quite maliciously manipulative in the sense that he feigned ignorance throughout the development of his dialogues in the republic in the way that he put the reader in simulation like potion as pushes him into the conclusion he allegedly had from the beginning, his revolution against the Paramenidian philosophy as well. Aristotle was more favored by modern philosopher but didn’t escape the criticism, mainly because of his glorification of phantasia in the cognitive life of humans. Still, both philosophers believe in the uplifting concept of an ultimate beauty, of a divine good that we humans, with the psyche of a god and a mortality of a being of the lower realm, naked and trembling besides or with the cosmos, will only wish to grasp one day.