The question "What can I know?" is a central philosophical question, famously posed by the philosopher Immanuel Kant. This question relates to epistemology, which is the branch of philosophy that examines the nature, origin, and limits of knowledge. Epistemology explores different kinds of knowledge, such as knowledge of facts, skills, and acquaintance through experience, and investigates how knowledge is justified or validated. Philosophically, it asks what kinds of things we can truly know and what the limits of human knowledge are. Kant contributed significantly to this question by suggesting that while we can know the appearances of things as structured by our senses and understanding, the things-in-themselves (the reality beyond our perception) are ultimately unknowable. The study of this question involves examining sources and justification of knowledge, including reason, perception, memory, and testimony. It also involves addressing skepticism—the doubt about human capability to attain certain knowledge—and balancing empiricism (knowledge from experience) with rationalism (knowledge independent of experience). In summary, "What can I know?" invites deep inquiry into the foundations and limits of human knowledge, a pursuit at the heart of philosophy and epistemology, as notably emphasized by Kant.