 There are other views of what there is that are less general than existence nihilism, existence monism, existence pluralism, or nominalism. For example, possibilism is the view that there are merely possible objects (see  section on possibilist realism in the entry on possible objects).  This view doesn’t say that every thing is a merely possible thing; it just says that the answer to the ontological question ought to include merely possible things. Mereological universalism says that whenever you have two or more things, there is an object composed of all and only those things (see  section on permissivism in entry on ordinary objects).  It doesn’t tell you that every thing is a composite thing; it just says that the answer to the ontological question needs to include such objects. Perdurantism says that objects are composed of temporal parts—at each time at which an object exists, there is an instantaneous object composed of all its parts at that time and is a part of it at that time, so those objects ought to be in the extension of the answer to the ontological question (see entry on  temporal parts).  Meinongianism says that there are non-existent objects, so they would include those objects in the extension of the answer to the ontological question (see entry on  nonexistent objects).