WordNet (r) 3.0 (2006):

school of thought
    n 1: a belief (or system of beliefs) accepted as authoritative
         by some group or school [syn: doctrine, philosophy,
         philosophical system, school of thought, ism]

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "school of thought":
   aesthetics, axiology, casuistry, cosmology, epistemology, ethics,
   first philosophy, gnosiology, logic, mental philosophy,
   metaphysics, moral philosophy, ontology, phenomenology,
   philosophastry, philosophic doctrine, philosophic system,
   philosophic theory, philosophical inquiry,
   philosophical speculation, philosophy, school of philosophy,
   science of being, sophistry, theory of beauty, theory of knowledge,
   value theory