Philosophy is a systematic study of general and fundamental questions concerning topics like existence, reason, knowledge, value, mind, and language. It is a rational and critical inquiry that reflects on its own methods and assumptions. Philosophers are intellectuals who typically speak and write well. They favor debate and the testing of conventions and beliefs. They are "gadflies" who ask questions which disturb those whose beliefs are uncritically accepted. Philosophers seek to understand themselves through a comprehension and evaluation of positions, arguments, ideas, and belief systems. They are usually committed to discovering truth and acting for the good. At its core, the study of metaphysics is the study of the nature of reality, of what exists in the world, what it is like, and how it is ordered. In metaphysics, philosophers wrestle with questions such as: Is there a God? What is truth? What is a person? What makes a person the same through time? Is the world strictly composed of matter? Do people have minds? If so, how is the mind related to the body? Do people have free wills? What is it for one event to cause another? Epistemology. The aim of philosophy is to deepen understanding. The hope is that by doing philosophy, we learn to think better, to act more wisely, and thereby help to improve the quality of all our lives.