| dc.description.abstract | There are reasons to believe that the correct principle governing which composite objects there are is the Unrestricted Fusion principle of classical mereology: for any satisfied condition there is an object composed of the things satisfying that condition. However, this principle appears to be inconsistent with so-called mereological junk. A world is junky if everything at that world is a proper part.
Unrestricted Fusion guarantees the existence of an object for any condition, including a universally satisfied trivial condition. The resulting object, the universe, exhausts all other objects so that everything is part of it. However, if the world were junky, then there would be an object of which the universe would be a proper part. However, since the universe exhausts everything, there can be no such object. Contradiction.
Still, junk is compatible with Unrestricted Fusion on a suitable weakening of classical mereology. Independent examples motivate a relaxation of the partial ordering of its proper and improper parthood relations, so that some objects consistently may be proper parts of themselves. The resulting non-wellfounded mereology takes proper parthood as its primitive relation and lets it obey only transitivity. Improper parthood can be defined in a standard way, and a standard strong supplementation principle added to complete the theory.
The resulting theory satisfies the same criteria used to argue for the possibility of junk. Moreover, it is consistent, independently motivated, and allows for Unrestricted Fusion even in the presence of junk: if the world were junky, the universe would exist as a proper part of itself. Alternatively, if such non-wellfoundedness is too disagreeable, one could claim, by parity of reasoning, that the criteria employed to establish the possibility of junk are flawed. If so, then the case for junk fails, and Unrestricted Fusion can be upheld. | eng |