Western philosophy is generally considered to have begun in ancient Greece as speculation about the underlying nature of the physical world. Philosophy comprised all areas of speculative thought and included the arts , sciences , and religion. In its earliest form it was indistinguishable from natural science. The writings of the earliest philosophers no longer exist, except for a few fragments cited by Aristotle and by other writers of later times. As special methods and principles were developed in the various areas of knowledge, each area acquired its own philosophical aspect, giving rise to the philosophy of art , of science , and of religion.
Philosophy deals with the most general questions of life, existence, and reality.
Philosophy is not a science as its questions can't be answered by experiments. Its concerned with rigourous conceptual analysis and reasoning, and critical examination of the grounds for fundamental beliefs. It seeks the most general, abstract, and ultimate character of the world in which we find ourselves. The philosophy of science seeks to clarify the objectives and means used by scientists, and what is the reliability of scientific theories. Epistemology - The Philosophy of Knowledge Epistemology is the branch of philosophy that studies the nature, limits, structure, origin, and criteria of knowledge, and differences between knowledge and belief.