This is the first thing I thought too, their position relative to the observer is a property of the object, it seems obvious. This applies to programming as we

This is the first thing I thought too, their position relative to the observer is a property of the object, it seems obvious. This applies to programming as well, in most OO languages two instances of a class with identical properties are still different due to their locations in memory. Most of these language have a distinction between value equal and reference equal. Also in databases you have the issue as well. Relational purist tend want natural keys for a item, but the reality is most database make artificial keys such that two items may have the same properties and are yet distinct due to the artificial key. For instance what is the natural key of a person? Even their DNA sequence may not be unique in the case of twins, or you may have incomplete information, either way you need to give them an artificial key. Much of seems to come down to the observer. In the case of the two spheres, two where observed and given a mental haecceitas instantly. If I examine the identical iron spheres then close my eyes and they are moved into opposite positions, then observe them again I will not be able to determine which is which or if they have changed. Computers are the same way they are typically recording facts and modelling things from the real world, imperfect models based on whats observed. What may be two objects may infact be one, a dup, etc..