The key to understanding the relationship between science and religion is to recognize that both are engaged in a quest for truth. Religion can do all sorts of things for you—guide you in life and strengthen you at the approach of death—but it cannot really do any of these things unless it is actually true. Otherwise it would amount to no more than an exercise in wishful thinking. And not only are science and religion both seeking truth: I believe they do so by gaining well-motivated beliefs that arise from actual encounter with reality.

In the case of science this is pretty obvious to most people, but in the case of religion it is less widely recognized. The New Atheists, such as Richard Dawkins, proclaim that religious people believe without evidence, or even willfully against the evidence. To take a less extreme example, I have many friends in the scientific world who are both wistful and wary about religion. They recognize that science on its own is not able to give a full account of our rich and complex world and that religion offers an enlarged account of reality. Yet they fear that it does so by submitting to the dictates of a supposedly unquestionable authority, be it an infallible book or an infallible institution. They picture faith as involving a willingness to grit one’s teeth and believe impossible things because one is told to do so. Of course they do not want to commit intellectual suicide, but neither do I.

I believe that I have motivations for my religious beliefs and in what follows I shall say something about one aspect of that, relevant to science. Of course the motivations for belief in science and religion are not identical, simply because the characters of the beliefs are not identical. Science and religion engage with different dimensions of reality and ask different questions about it.

Both Eyes Open

Science has achieved its very great success by the modesty of its ambition. It confines itself to considering the processes by which things happen and its basic question is “How?” Yet that is not the only question to ask if one is seeking full

understanding. There are also “Why?” questions, involving issues of meaning and value and purpose. Is there something going on in what is happening? These questions are deliberately bracketed out by science as part of its limiting self-definition, but we all know that they are meaningful and important questions to ask. The kettle is boiling because burning gas heats the water; the kettle is boiling because I want to make a cup of tea, and will you have one? We do not have to choose between these two answers. Both are true and necessary to a full understanding of the event of the boiling kettle.

I see science and religion as friends and not foes, therefore, complementing each other and not in conflict in their common quest for truthful understanding. While the questions they ask are different, the two inquiries interact with each other because their answers must be compatible. Saying that I have put the kettle in the refrigerator to make a cup of tea would not make much sense! Accounts of process and purpose must be congruent with each other. I like to say that I am “two-eyed,” viewing the world with both the eye of science and the eye of religion. I believe that this binocular vision enables me to see further and deeper that I could with either eye on its own. It grieves me when some religious people refuse to accept the genuine insights of science. Those who seek to serve the God of truth should welcome truth from whatever source it comes. By no means all truth comes from science, but certainly some does.

A Rational Universe

Let me now say something about motivations for religious belief, concentrating on an example that, interestingly enough, arises from the experience of doing science, but whose consideration takes us beyond the range of purely scientific explanation. I worked in fundamental physics, exploring with my colleagues the properties of the basic constituents of matter. A striking feature of this activity is that it is possible at all. Of course, evolutionary necessity can surely be supposed to have shaped our brains so that we can understand the everyday world in which we have to survive. But why can we also understand the subatomic quantum world, remote from direct impact on our lives and in its cloudy fitfulness quite different in character from the clear and orderly world of everyday experience? Quantum theory requires a totally counterintuitive manner of thinking.

The fact is that the universe has proved to be astonishingly rationally transparent to our enquiry. Moreover it has proved also to be astonishingly rationally beautiful. The key to unlocking the deepest secrets of the cosmos has turned out to be the seemingly abstract subject of mathematics. It has turned out, time and again, that really

successful physical theories are expressed in equations that have about them the unmistakable character of mathematical beauty (economy, elegance, etc.). The marvelous deep order of the universe offers its investigators the reward of wonder for their labors. Why are we so lucky? It would surely be intellectually lazy just to treat this as a happy accident. Scientists exploit these opportunities, but simply as scientists they are unable to explain them.

Seeing the universe as a divine creation makes cosmic intelligibility itself intelligible. I have been describing a physical world, which in its wonderful order might be described as “shot through with signs of mind.” I believe that it is coherent and satisfying to see this as an indication of the mind of the Creator lying behind the deep order of the universe. Here is an example of how religious understanding can complement and extend the insights of science in an intellectually satisfying manner, setting them in a broader and deeper context of understanding.

Exchanging Gifts

The gift that science in its turn offers to religion is to tell it about the nature and history of the natural world. One of the most fruitful of these gifts has been the recognition that we live in an evolving world. Quite contrary to commonly asserted belief, when Darwin published The Origin of Species it was not the final parting of the ways between science and religion. There were many believers who welcomed his insights, and one of these was Darwin’s clergyman friend Charles Kingsley. Kingsley said that, although God could no doubt have created a ready-made world, Darwin had shown us that God had done something cleverer than that by creating a world so endowed with fertility that creatures could be allowed to explore and bring to birth its potentiality in a word “to make themselves.” This pregnant phrase neatly encapsulates the theological way in which to think of the fact of biological evolution. The God of love is neither an indifferent Deistic Spectator, nor a Cosmic Tyrant exercizing relentless total control, but the One who gives to creatures sufficient freedom to be and make themselves.

Such a world of creaturely freedom is a great good, but it has an inescapable shadow side. The shuffling explorations of evolutionary process will have blind alleys and ragged edges as well as great fertility. Genetic mutations not only produce new forms of life but they are also a source of malignancy. One cannot have the one without the other. This offers religion some help as it wrestles with its greatest perplexity: the presence of suffering in a world held to be the creation of a good and powerful God. The agonizing fact of cancer is not something gratuitous that a God who was a bit more competent or a bit less callous could easily have eliminated. It is the necessary cost of a creation in which creatures are allowed to make themselves. I do not pretend that this insight removes all our perplexity, but I think it is modestly helpful.

Unexpected Possibility

There is another gift from science that I would like briefly to mention. It is the recognition that reality is often surprising beyond human powers to anticipate. Quantum theory’s discovery that light sometimes behaves like a wave (that is, spread out and flapping) and sometimes like a particle (a little bullet) provides a striking example. In 1899 such oxymoronic behavior would have seemed absolutely impossible, and in fact it took the physicists many years to figure out how it could be so. Science’s encounters with the often strange behavior of reality means that the natural question for a scientist to ask about a proposition, whether within science or beyond it, is not “Is it reasonable?”—as if we felt we knew beforehand the shape that rationality had to take. Instead, the question to ask is “What makes you think that might be the case?”: a question at once open to unexpected possibilities but demanding motivating evidence if a seemingly counterintuitive proposal is to be accepted. The duality of the human and the divine in Jesus Christ is a much deeper duality than that of wave and particle, but I believe that I have motivations for my Christian belief that it is true. But that is another story (see, for example, my The Faith of a Physicist).