Solipsism: The doctrine that I alone exist. The self can know only its feelings and changes. There is only subjective reality.
Solipsism is of importance to philosophy and psychology. Rene Descartes (1596-1650), the French mathematician, physicist and "father of modern philosophy", made solipsism a central issue in philosophy. Since solipsism has to do with how we learn and know, it concerns cognitive psychology.
The word "solipsism" is a composite of the Latin "solus" ("alone") and "ipse" ("self") = the self alone.