ABSTRACT
An essay by W. V. Quine begins with this passage:
Professor Marcus struck the right note when she represented me as suggesting that modern modal logic was conceived in sin: the sin of confusing use and mention. She rightly did not represent me as holding that modal logic requires confusion of use and mention. My point was a historical one, having to do with Russell’s confusion of ‘if–then’ with ‘implies’.
Lewis founded modern modal logic, but Russell provoked him to it. For whereas there is much to be said for the material conditional as a version of ‘if–then’, there is nothing to be said for it as a version of ‘implies’; and Russell called it implication, thus apparently leaving no place open for genuine deductive connections between sentences. Lewis moved to save the connections. But his was not, as one could have wished, to sort out Russell’s confusion of ‘implies’ with ‘if–then’. Instead, preserving that confusion, he propounded a strict conditional and called it implication. 1
