Final answer:
The most fundamental distinction in Plato's philosophy is the separation between the world of immutable Forms and the sensory-observable physical world. Through philosophical reasoning, one can apprehend the true Forms that are more real than the changing material world. This idealist view contrasts with Aristotle's emphasis on the physical world and particulars.
Step-by-step explanation:
The most fundamental distinction in Plato's philosophy is the division between the world of Forms (or Ideals) and the physical world. Plato's theory of Forms posits that there is a higher realm of truth and reality, beyond our sensory experience, which consists of perfect, immutable, and eternal forms.
These Forms represent the essences of various phenomena in the universe and can only be grasped intelligently through reason and philosophical contemplation.
According to Plato, the objects we perceive with our senses are merely shadows or reflections of these true Forms. For instance, while physical tables may vary in design, and are subject to change and decay, the Form of a table is ideal, unchanging, and eternal.
This concept is emblematic of Plato's Idealism, which views ideas as the truest reality, contrary to the material world which is in a constant state of flux and is, therefore, less real.
In contrast, Aristotle, a student of Plato, focused more on the importance of individual instances, or the particulars, arguing that without them, there would be no knowledge of the Forms. While Plato highlighted the transcendental world of the Forms, Aristotle emphasized empirical observation and the particulars of this worldly existence.