In 1948 Bertrand Russell debated Father Frederick C. Copleston, a Jesuit Roman Catholic priest. An agnostic, Russell made for a dramatic contrast with Fr. Copleston, who wrote the nineteen-volume work A History of Philosophy. The debate broke down into three separate arguments for the existence of God: the argument from contingency, the moral argument, and the religious argument.

The Argument from Contingency

Copleston supports the argument from contingency — essentially, that the world is contingent or non-necessary and depends on some necessary being for its existence. Half of the transcript of their debate is taken up with this issue. Copleston proposes a four-part definition of God: we mean by God a supreme personal being distinct from the world and creator of the world. Russell accepts the definition but explains that he does not think that the “non-existence of God can be proved.”

From the outset the debate reveals Russell's analytic tendencies, working on breaking down Copleston's claims about God. Copleston argues that in order to explain objects that exist you must “come to a being which contains within itself the reason for its own existence.” This is what he means by a “necessary being.”

But Russell, an empiricist, replies in a very Humean fashion: “I would only admit a necessary being if there were a being whose existence it is self-contradictory to deny.” The word necessary then applies to no one thing, since all things are contingent. So the word necessary is a useless word, except when it is being applied to analytic propositions like “A bachelor is an unmarried man” or “Irrational animals are animals.”

Copleston presses the point, arguing that “an infinite series of contingent beings will be, to my way of thinking, as unable to cause itself as one contingent being.” But Russell again applies his analytical scalpel: you get your concept of a cause from your observation of particular things; but the concept of cause doesn't apply to the total series of causes. The universe, Russell says, “is just there.”

The Religious Experience and Moral Arguments for God's Existence

After employing his argument from contingency, Copleston tries a familiar argument grounded in religious experience. Normal citizens and saints throughout history have heard voices or felt touched in some way by the presence of something outside of themselves. People have had experiences of “something transcending the self, something transcending all the normal objects of experience, something which cannot be pictured or conceptualized, but of the reality of which doubt is impossible … at least during the experience.”

The best way to explain the experience, Copleston continues, is that there is actually “some objective cause of that experience. I don't regard religious experience as a strict proof of the existence of God … but I think it is true to say that the best explanation of it is the existence of God.” (Italics added.) Here Copleston borrowed the scientific term “best explanation” to account for religious experiences. In short, if person X is having a religious experience of a God, there must be a cause for that experience, namely God himself.

Russell disagrees. People can all experience the same thing, like a clock, which tells them that the clock is not a hallucination. But religious experiences, by their nature, are experiences of individuals that “tend to be very private.” Moreover, if you assume whatever people report as being true, “including demons and devils — does the experience of them prove that they exist?” In short, some experience of X, something outside myself, “doesn't prove the existence of something outside of me,” according to Russell.

Copleston's “moral argument” for the existence of God claims that if there is a universal moral law, there must be “an author” of that law. But Russell contends that if there is a moral law, it is not absolute but always changing. For people have at various times thought cannibalism was a duty, not to mention segregation, slavery, the oppression of women, and so forth. This would seem to indicate that people's consciences are “amazingly different in different times and places.” The fact of variety seems to indicate that the conclusion does not follow: there is no one transcendent author of the moral law, but lots of different “terrestrial law” givers, like parents, teachers, and leaders.