The Collaborative International Dictionary of English v.0.48:

Systematizer \Sys"tem*a*ti`zer\, n.
   One who systematizes.
   [1913 Webster]

         Aristotle may be called the systematizer of his
         master's doctrines.                      --Harris.
   [1913 Webster]

WordNet (r) 3.0 (2006):

systematizer
    n 1: an organizer who puts things in order; "Aristotle was a
         great orderer of ideas" [syn: orderer, systematizer,
         systematiser, systemizer, systemiser, systematist]