Epistemology (from the Greek episteme meaning knowledge) is a core branch of philosophy that deals with the nature, origin, and scope of knowledge. It can be considered the study of knowledge as such, independent of any particular subject area that is known (e.g., math, science, economics). Historically, it has been one of the most investigated and most debated of all philosophical subjects. Much of this discussion concerns the justification of knowledge claims and has focused on how knowledge relates to concepts such as truth, belief, and evidence. Basic issues in epistemology include the role of experience, the role of logic, distinguishing knowing that" from "knowing how", the issue of faith and reason, and the status of certainty, doubt, and skepticism. Some topics in philosophy that are closely related to epistemology include Metaphysics, Philosophy of Mind, Logic, and Philosophy of Language.