I picked up this book in part because the authors are philosophers by training, and I thought it would provide an interesting perspective on ontologies, which are an important tool in health information systems and bioinformatics. In fact, it does provide useful perspective, but I still found it disappointing.
The first part of the book provides background in philosophy, and offers a defense of realism (as opposed to nominalism and idealism). This is fine, and the authors provide some good arguments, but it isn't entirely clear (to me, at least) how this constitutes an argument for Basic a Formal Ontology (BFO), the formal framework, the exposition of which forms the main part of the book. There are hints, of course. For example, one of the authors' criticisms of OWL is that it allows for different classes to have the same set of elements (extension). Of course, this is hardly surprising for any system built on first order predicate logic!
The final section compares BFO with the main technologies used to enable the semantic web: Resource Description Format (RDF) and Web Ontology Language (OWL). The authors conclude that these technologies are either too weak or awkward to use, and they have a valid point but instead of discussing alternatives in any detail, they refer to an ontology editor known as Protégé. Indeed, extensive references are a strong point of the book. Overall, I'd like to see more focus on technology, and perhaps more discussion of the implications of the choice of mathematical foundations for a theory of ontologies. Then again, perhaps this outside the scope of the present book.