Scientific skepticism or rational skepticism, sometimes referred to as skeptical inquiry, is a position in which one questions the veracity of claims lacking scientific evidence. In practice, the term most commonly refers to the examination of claims and theories that appear to be unscientific, rather than the routine discussions and challenges among scientists. Scientific skepticism differs from philosophical skepticism, which questions humans' ability to claim any knowledge about the nature of the world and how they perceive it, and the similar but distinct methodological skepticism, which is a systematic process of being skeptical about the truth of one's beliefs.