 Every scientific system implies a conceptual classification of the world into an ontology of fundamental entities and properties—it is an attempt to answer the question “What is the world really made of?” But it is exactly these ontologies that are most subject to radical change throughout the history of science. Therefore in the spirit of the principle of no privilege, it seems that we must say either that all these ontologies are true, ie: we must give a realistic interpretation of all of them or we must say they are all false. But they cannot all be true in the same world, because they contain conflicting answers to the question “What is the world made of?” Therefore they must all be false. (1976: 266)