| Platonist or transcendent realism holds that properties are abstract objects in the classical sense, of being nonmental, nonspatial, and causally inefficacious. |
| That is, abstract objects are not located anywhere in the physical universe, and they are also entirely nonmental, yet they have always existed and they always will exist. |
| Consider how most ordinary nonmental phenomena are explained. |
| This is the view that numbers are abstract objects, where an abstract object is both nonphysical and nonmental. |
| It is one of the impressive achievements of modern science that it seems to afford in principle quite illuminating explanations of almost every nonmental phenomenon one can think of. |
| However, since abstract objects must be nonphysical and nonmental if they exist at all, it is not obvious how one could ever determine whether they exist. |
