There are many different things in the world. There are trees, cars, buildings and pianos. But there are also thoughts, songs, universities and fictional characters. These objects seem to be organized in two sorts: concrete and abstract objects. Or, maybe we can divide them, more classically, between individuals, or particulars, and universals. There is also the view according to which there are arbitrary objects, as opposed to individual objects, and arbitrary objects are those which have a specific range, and present only properties common to all objects in their range. Or maybe not, arbitrary objects present those properties common to most objects in their range, like types. But are types arbitrary objects?
In this talk, we shall analyze these concepts, and others, finding out in what ways they are different - and why we seem to have come up with them -, and in what ways they are similar and intertwined.