Empiricism is a philosophical theory that emphasizes knowledge derived from sensory experience. It posits that all concepts and knowledge must be rooted in observable phenomena, making it a foundational principle in the scientific method. Key figures in empiricism include John Locke, David Hume, and George Berkeley, who argued that our understanding of the world is shaped by our experiences rather than innate ideas. This approach contrasts with rationalism, which asserts that reason and innate knowledge are the primary sources of understanding. Empiricism has significantly influenced modern science, encouraging experimentation and observation as essential tools for acquiring knowledge about the natural world.