• "Neo-Logicism? An Ontological Reduction of Mathematics to Metaphysics", Erkenntnis, 53/1-2 (2000), 219-265
• "The Road Between Pretense Theory and Object Theory", in Empty Names, Fiction, and the Puzzles of Non-Existence, A.~Everett and T.~Hofweber (eds.), Stanford: CSLI Publications, 2000, pp. 117-147
• "How to Say Goodbye to the Third Man", (coauthor: Francis Jeffry Pelletier), Noûs, 34/2 (2000): 165-202
• "A (Leibnizian) Theory of Concepts", Philosophiegeschichte und logische Analyse / Logical Analysis and History of Philosophy, 3 (2000), pp. 137-183
• "Natural Numbers and Natural Cardinals as Abstract Objects: A Partial Reconstruction of Frege's Grundgesetze in Object Theory", Journal of Philosophical Logic, 28/6 (1999), pp. 619-660
• A Classically-Based Theory of Impossible Worlds, Notre Dame Journal of Formal Logic, 38/4 (Fall 1997), pp. 640-660 (Special Issue: Graham Priest, Guest Editor)
• Naturalized Platonism vs. Platonized Naturalism (coauthor: Bernard Linsky), The Journal of Philosophy, XCII/10, October 1995, 525--555

Books:

• Abstract Objects: An Introduction to Axiomatic Metaphysics (Dordrecht: D. Reidel, 1983)
• Intensional Logic and the Metaphysics of Intentionality (Cambridge, MA: The MIT Press/Bradford Books, 1988)

• Philosophy 288: (Metaphysics Seminar)
• "Platonism, Formal Ontology and Naturalism" (Autumn 1996)