Filosofia How do we know what we know? What is the difference between a justified belief and an opinion? Can we ever be certain of anything? Epistemology investigates the nature, sources, and limits of knowledge. Skepticism—the view that true knowledge is impossible—is its most challenging enemy. Filosofia began not in a classroom, but in the marketplace and on the streets of ancient Greece. Thales of Miletus, often considered the first philosopher, rejected mythological explanations for natural phenomena. Instead of saying "lightning is Zeus's wrath," he asked, "What is the underlying substance of all things?" Filosofia
