Scientific skepticism or rational skepticism (also spelled scepticism), sometimes referred to as skeptical inquiry, is a position in which one questions the veracity of claims lacking empirical evidence. In practice, the term most commonly references the examination of claims and theories that appear to be beyond mainstream science, 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 (or doubting) the truth of one's beliefs.

The skeptical movement (British spelling: sceptical movement) is a contemporary social movement based on the idea of scientific skepticism. The movement has the goal of investigating claims made on fringe topics and determining whether they are supported by empirical research and are reproducible, as part of a methodological norm pursuing "the extension of certified knowledge".

Roots of the movement date at least from the 19th century, when people started publicly raising questions regarding the unquestioned acceptance of claims about spiritism, of various widely-held superstitions, and of pseudoscience. Publications such as those of the Dutch Vereniging tegen de Kwakzalverij (1881) also targeted medical quackery. Using as a template the Belgian organization founded in 1949, Comité Para, Americans Paul Kurtz and Marcello Truzzi founded the Committee for the Scientific Investigation of Claims of the Paranormal (CSICOP), in Amherst, New York, in 1976. Now known as the Committee for Skeptical Inquiry (CSI), this organization has inspired others to form similar groups worldwide.