C.S. Lewis was a man of many parts. His novels, allegories, and children's books achieved enormous popularity. He excelled as a spiritual writer and had some standing as a poet. In the academic field he was competent in philosophy, a master of the Greek and Latin classics, and outstanding as a literary critic.
But he is best known today as an apologist--probably the most successful Christian apologist of the twentieth century. Forty and more years after his death, his influence remains unabated. His works are read by Protestants and Catholics with equal relish. Enough books have been written on Lewis to fill several shrives of a bookcase.
Although Lewis' achievements in apologetics have been generally acclaimed, he is not without his critics. In his lifetime he had to meet objections from his fellow Anglican W. Norman Pittinger and the Catholic philosopher Elizabeth Anscombe. In 1985, twenty-two years after his death, a book-length refutation of Lewis' entire apologetical project was published by the philosopher John Beversluis. The various criticisms, however, reflect the presuppositions of their authors, which are not self-evidently true. One problem stems from the notion of "mere Christianity," which Lewis selected as the position to be defended. It is easy to object that there is no such thing as "mere Christianity" and that major differences, such as those between Protestants and Catholics, cannot be papered over. Aware of the objection, Lewis compared mere Christianity to a hall through which one finds one's way into the bedrooms of a house. The hall is not a place where anyone wishes to stay, but it is a place from which one can gain access to one or another of the rooms, recognizing that those in neighboring rooms are one's housemates. By "mere Christianity" Lewis means the common fund of doctrines and practices enshrined in Scripture and the early creeds, which are foundational for most Christian churches.
Lewis developed his apologetic for Christianity in three stages. First, he set out to establish the existence of God on grounds that are chiefly philosophical. Then he sought to demonstrate that God has preeminently revealed himself in Christ and in the Christian religion. Finally, he defended theism and Christianity against common objections, such as the problem of evil.
Against the prevalent agnosticism of his day and ours, Lewis believed it was possible to demonstrate the existence of God, at least in the sense of making God's existence vastly more likely than his non-existence. He was aware of the ontological argument, usually identified with Anselm and Descartes, and the cosmological arguments classically set forth by Thomas Aquinas. As for the ontological argument, which deduced God's existence from the very concept of a Necessary Being, he said in a letter to his brother Warren that the argument would not be valid unless one first established that the idea of Necessary Being from which it begins is objectively grounded and is not a mere fabrication of our minds. He did not reject the cosmological arguments from the facts of change, causality, and contingency, but he confessed in a letter to his friend Bede Griffiths that they were ineffective for him personally. But his own favorite proofs are those from morality, from reason, and from desire.
The argument from morality, rather fully set forth in Lewis' radio talks, The Case for Christianity, begins with the assertion that we are unconditionally bound to do good and avoid evil. All normal human beings spontaneously judge that certain actions are wrong and ought not to be done. They know they ought to be honest, truthful, temperate, just, and loving toward others--and that they are forbidden to commit theft, perjury, adultery, murder, and the like. About the details of the moral code there can be disagreements, but not about its obligatory character. The question is where the obligation comes from. According to the classical tradition of Christian theology, stemming from St. Paul, the obligation comes from God who, so to speak, writes His law upon the human heart, so that even people to whom the positive moral law has not been proclaimed have an inborn sense of what is commanded or prohibited. When they do wrong, they suffer from a bad conscience and realize that they deserve to be punished.
Lewis takes up and refutes the most common objections to this argument. He gives solid reasons for denying that the sense of moral obligation could arise from a herd instinct, from social convention, or from a Freudian superego. The only adequate explanation, he maintains, is that we are subject to a higher will, to which we are accountable for the use we make of our freedom. Addressing a popular audience, Lewis does not enter into every technicality or refute every difficulty, but he puts forth the essentials in simple and persuasive language.
Lewis' second favorite proof, the argument from reason, appears in his book Miracles. A certain kind of naturalism, he observes, characterizes rational thinking as a mere product of nervous reflexes, instincts, and habits. Lewis replies that physical or psychological conditioning cannot explain our power to make judgments about truth and error. We are conscious that our judgments are determined not by subrational forces but by reality as it impinges on our minds. The power to reach understanding through rational explanations is evidence of an affinity between the mind and reality. It is explicable only if there is an aboriginal mind that accounts for both intelligence and intelligibility.
Lewis' sketchy presentation of this argument leaves further work to be done. Having an ancestry that goes all the way back...