Final answer:
Kant suggests that if ancient philosophers had conceptualized substance in relation to noumena, they would not posit absolute existence due to noumena being beyond sensory experience. Plato's Forms and Aristotle's questions highlight the challenges in understanding substance as independent of perception. Kant proposes categories as innate frameworks to organize experiences into coherent concepts.
Step-by-step explanation:
Immanuel Kant argued that ancient philosophers considered matter or substance as the original and necessary foundation of reality, which when associated with appearance, it implied an absolute existence of objects as they appear to us. However, if these philosophers had considered substance in relation to noumena (things as they are in themselves, independent of our perception), they would not have arrived at the idea of absolute existence, because noumena are beyond our sensory experience and therefore beyond the realm of what can be said to exist in the same way as appearances do.
Plato's theory of Forms posits a realm where these unchanging entities exist, suggesting that the changeable world we experience is not where true, unchanging substance is located. Aristotle, Plato's student, questioned the practical influence of these immaterial Forms on the material world, illustrating the difficulty in conceptualizing substance outside of our experience. Following this line, Kant introduced the idea of categories, innate conceptual frameworks necessary for understanding our experiences, which allow us to organize sensations into coherent concepts like causation, self, and identity, even though they are not derived directly from those experiences.