[转载]Some fundamental questions of Ontology

The principal questions of ontology are "What can be said to exist?" and "Into what categories, if any, can we sort existing things?" Various philosophers have provided different answers to these questions.

One common approach is to divide the extant entities into groups called categories . Of course, such lists of categories differ widely from one another, and it is through the co-ordination of different categorial schemes that ontology relates to such fields as library science and artificial intelligence .

Further examples of ontological questions include:

• What is existence ?
• Is existence a property?
• Which entities, if any, are fundamental?
• How do the properties of an object relate to the object itself?
• What features are the essential , as opposed to merely accidental, attributes of a given object?
• How many levels of existence or ontological levels are there?
• What is a physical object ?
• Can one give an account of what it means to say that a physical object exists?
• Can one give an account of what it means to say that a non-physical entity exists?
• What constitutes the identity of an object?
• When does an object go out of existence, as opposed to merely changing ?