Fighting dualism in the classroom has been good fun. First of all, I incarnate in my own body the truth that mind depends and works in, to a great extent, the body.
"Now, let's turn to.... ah. Let's turn to... Well. Never mind. Er, let's go back to what we were just talking about. Yes. What were we just talking about?"
Yes, a simple backache brings all-powerful reason to its knees.
But seriously, we've been having great fun with dualism (Descartes) and utilitarianism (Mill) in the senior high school class. So, I thought I'd give the basic definitions the class has been working with.
Dualism, at least Cartesian dualism, says that all certainty is based in the "thinking thing," that is, me, "I." The foundation for clear and distinct knowledge is in the fact that I am. Now, that "I" is just mind. It's the thing doing the thinking. Bodies become a "probably conjecture" that we work with in science in order to master and possess nature. The mind and body are joined in a special way, but Descartes never really explains how they're joined and repeatedly insists that "I am essentially my mind." The body is non-essential to me.
Utilitarianism, in general, works on the principle that we ought to "maximize pleasure and minimize pain." Sounds great. John Stuart Mill made this a sort of cosmic principle: "Seek the greatest happiness (which he equates with pleasure) for the greatest number." I'm confirmed in my skepticism by none other than Karol Wojtyla (later Pope John Paul II), who says that inevitably utilitarianism becomes "greatest happiness for me."
Wojtyla wages a fascinating war on both dualism and utilitarianism in Love and Responsibility, his philosophical case for sexual ethics that predates the later, theological Theology of the Body addresses. It's probably my all-time favorite ethics book, and along the way it dabbles in metaphysics, aesthetics, and on and on. Here was a guy who did not believe in compartmentalization!