People with paranoid schizophrenia tend to be better able to reason and to plan activities
than people with other forms of schizophrenia, who are more subject to disordered thinking -- which could explain Rodger's ability, like that of the Unibomber, and the Colorado movie theater killer, to write his "manifesto" and plan his crimes.
http://www.mayoclinic.org/diseases-conditions/paranoid-schizophrenia/basics/definition/con-20029040
Paranoid schizophrenia is one of several types of schizophrenia, a chronic mental illness in which a person loses touch with reality (psychosis). The classic features of paranoid schizophrenia are having delusions and hearing things that aren't real.
With paranoid schizophrenia, your ability to think and function in daily life may be better than with other types of schizophrenia. You may not have as many problems with memory, concentration or dulled emotions. Still, paranoid schizophrenia is a serious, lifelong condition that can lead to many complications, including suicidal behavior.