Solipsism

Solipsism ( ; ) is the philosophical idea that only one's mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure; the external world and other minds cannot be known and might not exist outside the mind.

the epistemological problem of how one can know that others have minds, given that one can only observe the behavior of others

2014 school shooting in Otradnoye District, Moscow, Russia

psychological condition