| |
My copy of Wuthering Heights may be the same as my sister\'s in two different ways. If we each possess our own copy of the same print run of Wuthering Heights then our copies are qualitatively identical (from Latin identitas, ‘sameness’). The colour, size, typeface and spelling of my sister\'s copy is exactly the same as the colour, size, typeface and spelling of mine, so our different copies have the same qualities or properties. Alternatively, we may have been given a joint Christmas present. If there are not two copies with the same qualities or properties, but only one copy which we share, then they are numerically identical.
Leibniz\'s principle of the indiscernibility of identicals states that if a is numerically identical with b, then a and b are indiscernible: every property of a is a property of b, and vice versa. This intuitively obvious principle needs to be distinguished from the more controversial principle of the identity of indiscernibles, which states that if every property of a is a property of b, and vice versa, then a is numerically identical with b. The plausibility of the second principle depends on which properties are considered relevant. It seems that if a and b have exactly the same properties, including spatio-temporal properties, then they must be numerically identical. But if spatio-temporal properties are not considered relevant, the principle is less plausible. It seems that there could be two books exactly alike in all their properties, except that one exists at a different time or place to the other. AJ
See also rigid and non-rigid designators.Further reading D. Wiggins, Sameness and Substance. |
|
