1) Theory 
Follower of Reductionism as a philosophical school and set of explanatory principles.
The behaviourist approach is often accused as being reductionist. This means reducing our behaviours to mere stimulus-response associations. It ignores for example the influence of our cognitions (perception, attention, language, memory and thinking). The biological approach is similarly reductionist. This is because it explains thoughts, feelings,...
[adj] - of or relating to the theory of reductionism
adjective of or relating to the theory of reductionism; `reductionist arguments`