 This approach to drawing category distinctions among objects can avoid various potential problems and sources of skepticism. It is not subject to problems like those Smart raised for Ryle’s criterion, for days of the week clearly have different identity conditions than do persons, whereas beds and chairs seem to share identity conditions (those suitable for artifacts). Such a method of drawing out categories also is not subject to the sorts of skepticism raised above for category systems. Here there is no claim to provide an exhaustive list of categories, and for a principled reason: different categories may come into discussion as long as nominative terms or concepts associated with distinct identity conditions may be invented.