Richard Swinburne: Probability, Experience, and the Existence of God

Richard Swinburne: Probability, Experience, and the Existence of God

Richard Granville Swinburne (born 1934) is a British philosopher of religion and Emeritus Professor of Philosophy at the University of Oxford. He is widely regarded as one of the most important and influential defenders of theism in contemporary philosophy. Over a career spanning more than half a century, Swinburne has developed a comprehensive, systematic case for the existence of God, drawing on probability theory, the philosophy of science, and careful analysis of religious experience. His major work, The Existence of God (first edition 1979; second edition 2004), is a landmark in the philosophy of religion. For AQA A-Level Religious Studies (specification 7062), Swinburne is essential for understanding probabilistic arguments for God, the evidential value of religious experience, and responses to the problem of evil.

Swinburne’s Method: Cumulative Probability

Swinburne’s approach to the existence of God is distinctive in its use of probability theory, particularly Bayes’ theorem. Rather than offering a single, decisive proof of God’s existence, Swinburne argues that the case for God is cumulative: each piece of evidence (the existence of the universe, its order, the existence of consciousness, religious experience, etc.) raises the probability of God’s existence, and the cumulative weight of all the evidence makes theism more probable than not.

Bayes’ theorem provides a formal framework for calculating how evidence affects the probability of a hypothesis. In simplified terms:

• The prior probability of God’s existence is how likely God’s existence is before considering the evidence. Swinburne argues that the hypothesis of theism is simple (it postulates a single entity with a small number of properties: omnipotence, omniscience, perfect goodness) and that simpler hypotheses have higher prior probabilities.
• The likelihood is how probable the evidence (the existence and order of the universe, consciousness, religious experience, etc.) is on the assumption that God exists, compared with how probable it is on the assumption that God does not exist.
• If the evidence is more probable on the assumption that God exists than on the assumption that God does not exist, then the evidence raises the probability of God’s existence (and vice versa).

Swinburne concluded that the total evidence makes the existence of God more probable than not — that is, the probability of God’s existence, given all the evidence, is greater than 0.5.

The Cosmological Argument from Probability

Swinburne recast the traditional cosmological argument in probabilistic terms. The question is not “Does the existence of the universe prove God?” but “Is the existence of the universe more probable if God exists than if God does not exist?”

• If there is no God, the existence of the universe is a brute fact — something that just happens to be the case, with no explanation. The probability of a complex physical universe existing for no reason at all is very low.
• If God exists, the existence of the universe is to be expected, because a perfectly good God would have reason to create a universe containing conscious beings capable of moral and intellectual development.
• Therefore, the existence of the universe is more probable on theism than on atheism, and the existence of the universe raises the probability of God’s existence.

The Design Argument from Temporal Order

Swinburne distinguished between two types of design argument:

• Design from spatial order (the argument from the complexity and purposiveness of individual organisms — e.g. the eye, the wing). Swinburne acknowledged that this type of design is now largely explained by Darwinian evolution and is therefore of limited value as an argument for God.
• Design from temporal order (the argument from the regularity and law-governed character of the universe — the fact that nature operates according to consistent, mathematically describable laws). This, Swinburne argued, is not explained by evolution, because evolution itself presupposes the existence of natural laws. Why does the universe operate according to regular laws rather than behaving chaotically? The existence of natural laws is more probable if there is a God who chose to create an orderly universe than if the universe exists without explanation.

Swinburne drew an important distinction between scientific explanation (which explains events in terms of prior events and natural laws) and personal explanation (which explains events in terms of the intentions and actions of an agent). Science can explain particular events within the universe by appeal to natural laws, but it cannot explain why there are natural laws at all. This ultimate question requires a personal explanation — an explanation in terms of the intentions of a rational agent, namely God.

Religious Experience: The Principles of Credulity and Testimony

Swinburne mounted one of the most influential philosophical defences of the evidential value of religious experience. His argument, developed in The Existence of God (chapter 13) and in Is There a God? (1996), rests on two key principles: