"Metaphysical questions relating to what ex­ists do not seem to fade away" notes Jack Kaminsky in this book, which takes as its starting point the Quinian view that we de­termine what exists by means of the formal systems we construct to explain the world. This starting point, Kaminsky points out, is not novel; philosophers have often tried to construct formal systems, and from these systems they have been able to deduce what can be said to exist. Contemporary formal systems are different from earlier ones, how­ever, because they make more extensive use of the results of linguistics, logic, and mathe­matics studies. But these contemporary formal systems also must state eventually what their commitments to existence are, and they must be able to show their commit­ments to be free of paradox, ambiguity, and contradiction. Given these conditions, Kaminsky exam­ines the difficulties inherent in the existence claims of contemporary formal language systems. To do this he uses only a minimum of the technical elements of propositional and first-order quantificational logic. He concludes: many existential commitments are relative to the formal systems of time; some commitments seem to be absolute; and some problems--those relating to vacuous terms--arise only because no distinction is made between humanly constructed objects and naturally constructed objects.