In the first chapter, Swinburne provides a mostly traditional defination of God: omnipotent, omniscient, perfectly good, etc., but "neither male nor female." Having defined his god, he proceeds in chapters two through five to argue that theism, being the simplest ultimate explanation of everything observed, is more likely to be true than materialism. In making this claim, however, he runs into three problems. First, he must construct a jury-rigged definition of what a good theory is. He makes a great deal of simplicity as being the most important virtue of any theory. He must do this because his theistic theory, while being "simple," predicts nothing testable. However, scientists value theories for not only simplicity but also yielding accurate, testable predictions.
Second, Swinburn's theistic theory, although simple in that it postulates only one ultimate cause, cannot replace the materialistic explanations of science and, thus, posits an additional entity. His theism, then, is not an application of Ockham's razor that "entities are not to be multiplied beyond necessity." He tries to get around this problem by claiming that materialistic explanations are not "where any rational enquirer will stop" because, "The apparently coincidental cries out for explanation." But his contention is not supported by the evidence, for even the most common occurrences bubble up from and float upon the universal ocean of improbability. For example, the chances of any particular sperm fertilizing any particular egg are almost nil. Nevertheless, sexual reproduction, via millions of sperms and eggs, produces far more individuals than can survive.
This suffering driven by overpopulation brings up the third difficulty in Swinburne's theism--"Why God Allows Evil." He claims that the "theory of ultimate explanation" most likely to be true "is the simplest theory which predicts the observable phenomena," and he adds that "theism provides by far the simplest explanation of all phenomena." Swinburne is certainly wrong here. A theism that postulates an omnipotent, benevolent god neither predicts nor explains evil. Theodicies attempting to justify such a god allowing evil end up asserting that evil is good. Swinburne's attempt does not escape doing the same. He says that "according to the free-will defense, it is the natural possibility of moral evil which is the necessary condition of the great good, not the actual evil itself." But his other statements suggest worse. "I need to want to...see you hurt, if I am to have [a] choice between good and evil. This depravity is itself an evil which is the necessary condition of the greater good." "Being allowed to suffer to make possible a great good is a privilege, even if the privilege is forced upon you." "I am fortunate if the natural possibility of my suffering if you choose to hurt me is the vehicle which makes your choice really matter." There you have it; evil is good in that it make goodness better.
In the last chapter, Swinburne discusses "How the Existence of God Explains Miracles and Religious Experiences." The whole notions, however, of positing God as an ultimate explanation for everything from the universe to consciousness and religious experiences, if it may not be called a "God of the gaps," certainly is open to the charge of being a "God of the limits." In short, Swinburne is a champion of ad hoc hypotheses in defense of theism.