  But this only excludes reidentifications: presumably I can identify the moving whiteness or the moving seeing until it changes, even if this only gives me an instant in which to identify it.  This point renders McDowell’s version, as it stands, an invalid argument. If it is on his account possible to identify the moving whiteness until it changes, then it is on his account possible to identify the moving whiteness. But if that is possible, then his argument contradicts itself: for it goes on to deny this possibility.