The empiricist argument holds that if we explore the biological roots of moral behavior, and explain their material origins and biases, we should be able to fashion a wise and enduring ethical consensus. The current expansion of scientific inquiry into the deeper processes of human thought makes this venture feasible.

The choice between transcendentalism and empiricism will be the coming century's version of the struggle for men's souls. Moral reasoning will either remain centered in idioms of theology and philosophy, where it is now, or shift toward science-based material analysis. Where it settles will depend on which world view is proved correct, or at least which is more widely perceived to be correct.

Ethicists, scholars who specialize in moral reasoning, tend not to declare themselves on the foundations of ethics, or to admit fallibility. Rarely do we see an argument that opens with the simple statement This is my starting point, and it could be wrong. Ethicists instead favor a fretful passage from the particular to the ambiguous, or the reverse -- vagueness into hard cases. I suspect that almost all are transcendentalists at heart, but they rarely say so in simple declarative sentences. One cannot blame them very much; explaining the ineffable is difficult.

I am an empiricist. On religion I lean toward deism, but consider its proof largely a problem in astrophysics. The existence of a God who created the universe (as envisioned by deism) is possible, and the question may eventually be settled, perhaps by forms of material evidence not yet imagined. Or the matter may be forever beyond human reach. In contrast, and of far greater importance to humanity, the idea of a biological God, one who directs organic evolution and intervenes in human affairs (as envisioned by theism), is increasingly contravened by biology and the brain sciences.

The same evidence, I believe, favors a purely material origin of ethics, and it meets the criterion of consilience: causal explanations of brain activity and evolution, while imperfect, already cover most facts known about behavior we term "moral." Although this conception is relativistic (in other words, dependent on personal viewpoint), it can, if evolved carefully, lead more directly and safely to stable moral codes than can transcendentalism, which is also, when one thinks about it, ultimately relativistic.

Of course, lest I forget, I may be wrong.

Transcendentalism Versus Empiricism

THE argument of the empiricist has roots that go back to Aristotle's Nicomachean Ethics and, in the beginning of the modern era, to David Hume's A Treatise of Human Nature (1739-1740). The first clear evolutionary elaboration of it was by Charles Darwin, in The Descent of Man (1871).

Again, religious transcendentalism is bolstered by secular transcendentalism, to which it is fundamentally similar. Immanuel Kant, judged by history the greatest of secular philosophers, addressed moral reasoning very much as a theologian. Human beings, he argued, are independent moral agents with a wholly free will, capable of obeying or breaking moral law: "There is in man a power of self-determination, independent of any coercion through sensuous impulses." Our minds are subject to a categorical imperative, Kant said, of what our actions ought to be. The imperative is a good in itself alone, apart from all other considerations, and it can be recognized by this rule: "Act only on that maxim you wish will become a universal law." Most important, and transcendental, ought has no place in nature. Nature, Kant said, is a system of cause and effect, whereas moral choice is a matter of free will, absent cause and effect. In making moral choices, in rising above mere instinct, human beings transcend the realm of nature and enter a realm of freedom that belongs exclusively to them as rational creatures.