  However, this approach has been criticised on the grounds (among others) that we can surely conceive of two absolutely indistinguishable objects: thinking of Star Trek, we could imagine a replicator device which precisely reproduces an object, such as a coin or even a person, giving two such objects exactly the same set of properties. Not quite, one might respond, since these two objects do not and indeed cannot exist at the same place at the same time; that is, they do not possess the same spatio-temporal properties. In terms of these properties, then, the objects can still be distinguished and hence regarded as different individuals. Clearly, then, this approach to the issue of individuality must be underpinned by the assumption that individual objects are impenetrable.