Regis Pierre-Sylvain; Reichenbach Hans; Reid Thomas; reification; relativism; renaissance; replacement - rules of; representationalism; res cogitans - res extensa; residues - method of; responsibility; Ricoeur Paul; Riemann Georg Friedrich Bernhard; rigid designator; Ritchie David George; Rohault Jacques; Rorty Richard; Ross William David; Rousseau Jean-Jacques; Royce Josiah; Ruddick Sara Loop; Russell Bertrand Arthur William; Ryle Gilbert;