Raham Asha
Raymond M. Smullyan
Reductio ad absurdum
Reflexivity
Relevance logics
René Descartes
Ring
Ronald Rivest
Routley Star
Rudolf Carnap
Russell
Russell's paradox
Russellian
Ruth Barcan Marcus
racism
ray
realism
reductionism
reductivism
reference
reflexive
regular matrix
relational semantics
relativism
relativism
relativist
renate
representationalism
respectively
rigour
rules of derivation