Solipsism is the theory that the only thing that truly exists and can be proven to exist is the self. Therefore, we cannot have true knowledge of anything that exists outside of ourselves. Problematic in solipsism is the knowledge of other minds. If a person believes only his mind exists, he cannot know if other individuals really exist or are just a projection of his own mind. This problem extends to reality as well, since such a person could not truly know if objects can exist since he can only know his own mind exists.
Solipsism is internally consistent but not true. First of all, if a person believes that everything which exists outside of himself is not real, and is a manifestation of his own mind, then no matter what is said to him can ultimately be rejected, or accepted, or whatever since it is all part of the projection of his own mind.
The problem is that it cannot be proven to be true or false -- not to mention that it contradicts Scripture. Still, how could a person who holds to solipsism know that it is a proper representation of reality? He would not be able to test or refute the philosophy even with evidence and logic to the contrary exists since it can all be dismissed as figments of his imagination.
Slipsism is a mental trap.