Empiricism.

Empiricism is the theory of philosophy that finds all knowledge comes from experience—information gathered through hearing, sight, smell, taste, and touch, or reasoned in the mind based on experience. The term comes from the ancient Greek word empeiria, meaning "experience." Empiricism is based on the idea that all ideas are a posteriori, Latin for "from the latter." This differs from the rationalist idea that concepts may be a priori, "from the former," meaning they do not rely on experience.