MATERIALISTS claim that in principle mentality could be accounted for entirely by properties of matter. They must, of course, clarify, as far as possible, the precise scope of the concept "properties of matter." According to materialists there exists only one type of "substance" in the universe, namely matter. Sophisticated experimental and theoretical analyses have led contemporary physicists to interpret known material entities as being composed of two classes of elementary particles, namely quarks and leptons and constituents of interaction fields that (...) mediate interactions between some or all of the elementary particles and which comprise photons, gluons, intermediate bosons and gravitons. For instance, protons and neutrons are composed--by hypothesis--of quarks, while electrons are probably the most familiar leptons. Whether any analyzed and postulated elementary particles and constituents of interaction fields are "ultimate" components of matter can never be known. It remains always possible that more basic subcomponents of known components will be discovered. This has happened repeatedly throughout the history of physics. Hence, what physicists understand by the "physical properties" of the basic components of matter must always remain expressed in terms of usually intricate hypothetico-deductive theories which are tentative and fallible. Contemporary relativistic quantum mechanics of elementary particles and of interaction fields provide typical examples of such hypothetico-deductive theories relating to present known basic components of matter. (shrink)