Philosophical skepticism (Greek σκέψις - skepsis meaning "enquiry") is a school of philosophical thought that began in Ancient Greece and a method that crosses many different cultures. Many skeptics examine the meaning systems of their times, and this can often result in a position of doubt. This skepticism can be either disbelief in philosophical solutions, agnosticism, or even rejecting the reality of the outside world. One kind of scientific skepticism talks about looking into claims that lack evidence that can be seen.
In Islamic philosophy, philosophical skepticism was started by Al-Ghazali, known in the West as "Algazel", as a part of the orthodox Ash'ari school of Islamic theology. It has been said that Rene Descartes' ideas in Discourse on the Method may have been influenced by Al-Ghazli.