Philosopher Leo Strauss criticizes Weber for attempting to isolate reason completely from opinion. Strauss acknowledges the philosophical trouble of deriving 'ought' from 'is', but argues that what Weber has done in his framing of this puzzle is in fact deny altogether that the ‘ought’ is within reach of human reason.[16] Strauss worries that if Weber is right, we are left with a world in which the knowable truth is a truth that cannot be evaluated according to ethical standards.