Anti-psychologism Conceptualism Constructivism Conventionalism Counterpart theory Deflationary theory of truth Dialetheism Fictionalism Formalism (philosophy) Game theory Illuminationist philosophy Logical atomism Logical holism Logicism Modal fictionalism Nominalism Object theory Polylogism Pragmatism Preintuitionism Proof theory Psychologism Ramism Semantic theory of truth Sophism Trivialism Ultrafinitism