You may just be hung up on the examples of Sidney and San Francisco, which are not essential to the point. Suppose I bring you a 5 pound weight a 1 pound weight, and say &quot;this is heavier than that&quot;. Then we can substitute those for Sydney and San Francisco in the example.<p>Put another way, the metaphysical status of cities is not a direct consequence or assumption of the metaphysics of mathematical entities.