Precognition (from the Latin prae-, "before" and cognitio, "acquiring knowledge"), also called prescience, future vision, or future sight, is a claimed psychic ability to see events in the future. As with other paranormal phenomena, there is no accepted scientific evidence that precognition is a real effect, and it is widely considered to be pseudoscience. Precognition also appears to violate the principle of causality, that an effect cannot occur before its cause.