Final answer:
Epicurus introduced a mysterious, nameless substance to explain sense-perception, aligning with his empirical approach while accounting for sensory experiences without invoking an immaterial soul. This substance reconciled empirical knowledge with his philosophy that understanding human nature through senses is essential for pursuing pleasure, the ultimate goal of life.
Step-by-step explanation:
In exploring the concept of soul, Epicurus introduced a mysterious, nameless substance to explain sense-perception as a way to reconcile his empirical philosophy with the natural phenomena humans experience. Epicurus, an empiricist, posited that all knowledge comes from sense perception and his addition of a nameless substance could be seen as an attempt to remain within a naturalistic framework while accounting for the complex nature of sensory experience, without resorting to supernatural explanations like the immaterial soul.
This approach aligns with his overall philosophy where he favored natural explanations for phenomena. By avoiding the acceptance of an immaterial soul, he maintained a consistent view that material substances, including this unknown one, were responsible for the qualities and sensations we experience. This mysterious substance facilitated Epicurus's need to explain sense perception without contradicting his ethical naturalism that states living a good life requires an understanding of human nature, which is derived from sensory knowledge.
Thus, the notion of a nameless substance serves as a bridge between empirical observation and his ethical views on how to pursue pleasure as the ultimate goal of life.