Kaphtu
1. The Golden Gryphon Feather (1979)
2. The Stolen Goddess (1980)
3. The Mirror of Helen (1983)

Lost Tales of Kaphtu
1. The Gryphon Seal (2005)

Logic for Philosophers (1971)
Solutions to Odd-numbered Exercises to Accompany Logic for Philosophers (1971)
Lord Of The Elves and Eldils: Fantasy And Philosophy In C. S. Lewis And J. R. R. Tolkien (1974) (see C S Lewis and J R R Tolkien)
Reason to Believe (1974)
Philosophically Speaking (1975)
Thinking About Ethics (1976)
Thinking About Religion: A Philosophical Introduction to Religion (1978)
Logic: Argument, Refutation, and Proof (1979)
C S Lewis' Case for the Christian Faith (1982) (see C S Lewis)
Philosophical Questions: An Introductory Anthology (1984) (with Peter J Kreeft, Michael H MacDonald)
Moral Dilemmas (1985)
A Logical Introduction to Philosophy (1988)
Logical Thinking (1992)
J.R.R.Tolkien: Myth, Morality and Religion (2003) (see J R R Tolkien)