Van Inwagen’s main argument is that necessary and sufficient (particularly sufficient) conditions cannot be given for the kind of cohesion of parts that is supposed to bind atoms into complexes. None of the standard candidates—contact, fastening, adhesion, fusion, nor any acceptable disjunction of them—will suffice. They all have counterexamples. So the notion cannot be well defined. The arguments are subtle and interesting. The question might be raised whether van Inwagen gives sufficient consi