There is much discussion in philosophy about the "external world". Questions arise about what we know about the external world (if we know anything at all) and some even question the very existence of the external world. Kant considers it a "scandal" that philosophy has not offered a proof of the external world. Skeptics are quick to point out that the external world is inaccessible to us and perhaps even question whether or not such a thing exists.
Along with these skeptics, I, too, deny the external world but on entirely different grounds and in a way that is quite distinct from the usual skeptical inquiries. For what I deny is not that there is no external world but rather that the world is not partitioned into "external" and "internal" to begin with. Those who question our knowledge, the existence or request a proof of the external world take for granted that distinction between an "internal" and "external" world. I deny that very distinction. At the very least, it needs to be shown that the world is divided in such a way; to me, there is not any clear reason for partitioning the world in such a way.