Stanford Encyclopedia of Philosophy A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z Arthur Prior Arthur Prior (1914-1969) undertook pioneering work in intensional logic at a time when modality and intensional concepts in general were under attack. He invented tense logic and was principal theoretician of the movement to apply modal syntax to ...