  (i) The Principle appeals to empiricists. For how could we ever have empirical evidence for two indiscernible items? If we did, empiricists might say, then they would have to be differently related to us. Unless we ourselves have exact replicas, which is implausible, we are the unique beings with pure properties X, Y, Z etc. Hence the empirically distinguishable objects have different pure properties, namely, being related in different ways to the unique things with X, Y, Z, etc. From this and the empiricist premiss that there are no things which are not empirically distinguishable, we would conclude that the Weak Principle holds. Presumably the premiss would not be proposed as anything more than contingently true. For there are possible situations in which there would be theoretical reasons for believing in indiscernible items as a consequence of a theory which best explains the empirical data. Thus we might come to hold a theory of the origins of the physical universe which had large amounts of empirical support, and which implied that, in addition to our enormously complicated universe, various simpler ones had been generated. For some of the simplest universes this theory might imply that there were exact replicas. In that case the Weak Principle would fail. 