philosophy

(noun) a belief (or system of beliefs) accepted as authoritative by some group or school. Synonyms: doctrine, philosophical system, school of thought, ism.

(noun) the rational investigation of questions about existence and knowledge and ethics.

(noun) any personal belief about how to live or how to deal with a situation. Examples: "Self-indulgence was his only philosophy." "My father's philosophy of child-rearing was to let mother do it."