It is also easy to see that strong individual supervenience entails strong global supervenience. Suppose that A-properties fail to strongly globally supervene on B-properties. That means that there are two worlds w1 and w2 between which there is a B-preserving isomorphism that fails to be A-preserving. So, for some x in w1, the image of x under I in w2—call it y—has all and only the same B-properties as x in w1, but differs from x in w1 in at least one of its A-properties. But that is just to sa