 Bertrand Russell dismissed Bradley’s argument on the grounds that philosophers who disbelieve in the reality of external relations cannot possibly interpret those numerous parts of sciences which appear to be committed to external relations (Russell 1924: 339). Russell’s argument bears comparison to Quine’s famous indispensability argument for mathematics: just as we cannot make sense of scientific discourse without taking seriously those portions irredeemably committed to, e.g., numbers, we cannot make sense of scientific discourse without taking seriously those portions committed to, e.g., spatio-temporal relations (Quine 1981: 149–50). From a methodological point of view, Russell deemed it more likely that an error is concealed somewhere in Bradley’s argument than that modern science should have incorporated so fundamental a falsehood, i.e., portrayed a world of spatio-temporal relations when really there are none. Of course even if we have good or even overwhelming reason to think that Bradley’s argument must be wrong, this doesn’t relieve us of the philosophical responsibility of determining where exactly Bradley slipped up.