The question "What can I know?" is famously associated with the philosopher Immanuel Kant. He wrestled with epistemological questions about the limits and scope of human knowledge, and his work is central to the field of epistemology, the study of knowledge—how it is acquired and what it entails. Kant's philosophy deeply investigates what knowledge is possible for humans and the conditions under which knowledge can be attained.

Philosophy, more broadly, is the systematic study of fundamental questions about existence, knowledge, reason, morality, and more. It includes major branches such as epistemology (study of knowledge), ethics (moral principles), logic (correct reasoning), and metaphysics (nature of reality).

Notable philosophers who shaped the field include Socrates, who famously questioned people to uncover knowledge and moral wisdom; René Descartes, who is known for the statement "I think, therefore I am"; and many others like Aristotle, Kant, Nietzsche, and Kierkegaard, each contributing uniquely to how knowledge and existence are understood.

If the interest is specifically in understanding "what can I know?" from a philosophical standpoint, it is a central question in epistemology best explored through Kant's work and the tradition he represents. Would you like to know more about a particular philosopher or branch of philosophy?