You may have heard the claim that God cannot answer prayers because that would violate the laws of nature, which determine everything that happens. This view reflects an outdated, but still popular interpretation of the laws of nature. It dates back to the time when people were deeply impressed by the success of Newton’s laws at predicting the motion of planets and of projectiles. With the help of these laws one could apparently calculate the future motion of all objects provided their initial positions and velocities, as well as all forces acting between them, were known. The world seemed similar to a huge clockwork running according to the mechanical interaction of its cogwheels and springs, just as the clockmaker had constructed it. At creation, God had set up the universe with its internal mechanisms by which it had been running ever since on its unalterable course. Some thinkers extrapolated this mechanistic view to the point of abolishing God altogether, postulating that the world is not created but has existed forever.

In the twentieth century, chaos theory and quantum physics shattered the mechanistic worldview. Still, many scientists hold onto a somewhat adjusted version of it. They want to reduce all of nature to the four fundamental forces (gravity, electromagnetic force, weak and strong nuclear force) and to the elementary particles of which all matter is composed. According to their interpretation of the laws of physics, the dynamics on the ‘fundamental’ microscopic scale determine everything happening on the larger scale of our everyday world.In the twentieth century, chaos theory and quantum physics shattered the mechanistic worldview. This reductionst view has taken the place of the old mechanistic view. Other scientists include some laws acting on larger scales into the set of ‘fundamental laws.’ However, if they share the view that the laws of physics determine the course of the world, they are also physicalists, albeit non-reductionist ones.

Even a considerable number of Christians accept this view of nature and hence face the question of whether and how God can act in the world. If they believe that God does act in the world, for instance in answer to prayer, they may adopt a deterministic, a compatibilist, or an interventionalist view. The deterministic view holds that God in his omniscience and foreknowledge planned all his future actions at the creation of the world and set up its initial state accordingly. For this to be true, however, the details of the motion of quantum particles and of quantum fluctuations during the early stage of the universe had to include somehow everything that would happen in the future. But this contradicts the consensus that the early universe was in thermal equilibrium and could therefore not contain hidden information about the future. The compatibilist view holds that while the motion of all atoms is fully governed by the laws of physics, it simultaneously implements the actions of God. However, this view faces the problem of overdetermination and is therefore implausible to me. The interventionalist view holds that God can interfere in the world and change its course. His interference acts like a temporary additional force that changes the subsequent events. C. S. Lewis defends this view compellingly in his book Miracles. I know a couple of present-day scientists and philosophers who hold this view.

However, I don’t share the deterministic, the compatibilist, or the interventionalist view as all three of them are based on the premise that the laws of physics are sufficient to determine the course of the world. For this to be the case, the laws of physics must be all-encompassing, and not merely an approximation but completely accurate. Philosophers of science speak of the ‘causal closure’ of the physical world: Every physical event has a fully physical cause. Viewing the physical world as causally closed is mistaken in my opinion. Consider for example the events in the human brain.Viewing the physical world as causally closed is mistaken in my opinion. We can describe scientifically how electrical and chemical signals propagate through its highly connected neutral network. If we could precisely measure what happens in each neural cell and at each synapse, we would not find any violation of the laws of physics and chemistry. At the same time, many details would not be predictable and appear random, as is usual on the microscopic level.

Now let us focus on the activity of my brain while I am writing this text. What I write is guided by the purpose of my message and my line of argument. Where in the activity of my brain are the purpose and logic hidden that guide my writing? We cannot pin them down nor detect them with physical methods. Nevertheless, they influence my brain, indicating that the physical and chemical events in my brain are causally open to influences from outside physics. The brain is sufficiently complex to support these influences. A computer might help to make this plausible: While it performs calculations no event in its interior is in conflict with the laws of physics, yet the calculations follow their own immaterial logic.

These considerations provide room for God’s action. They show that the laws of nature are not all-encompassing; they do not exclude the simultaneous influence of other causes. Wouldn’t it be strange if God had created a world that operates according to laws prohibiting him from having the loving, personal relationship to his creation that he desires? Of course, the laws of nature by themselves are already an action of God. They are his sustaining action. The reliable course of the world enables us humans to plan and act, to invent devices and develop machines. But according to Christian tradition, God’s relationship to his creation also has a personal dimension. He can guide us, answer our prayers, heal and strengthen us.In contrast, proponents of the causal openness of physics maintain that the laws of physics are not sufficient to prescribe the course of nature. And in my opinion he can do this without our instruments finding any deviation from the laws of physics, similar to what I wrote above about the events in our brain. Here lies the difference to the interventionalist view according to which one could, in principle, discover that a non-physical influence had caused a deviation from what would have happened if God had not intervened. In contrast, proponents of the causal openness of physics maintain that the laws of physics are not sufficient to prescribe the course of nature.

This does not mean that God’s action is hidden in quantum randomness. Some people think that God fixes the outcome of each quantum event such that many quantum events together bring about what God wants to do in the world. No, God does not influence the world bottom-up from the microscopic level, but he acts top-down, from the whole on the parts. No part of the physical world is completely isolated from the rest of the world and fully governed by its intrinsic processes. Laboratory environments can shield a system from many external influences, but not from gravity, nor can they prevent quintillions of neutrinos from crossing the lab every second. So, every object is embedded into a context from which it cannot be fully isolated. All objects that exist today have been shaped by their environment. Many objects require a continuous interaction with their environment in order to exist. For instance, living beings need food, oxygen, and interaction with other living beings, otherwise they die. Even quantum systems depend on their environment, as it determines which types of quantum events can occur at all. This is most obvious for a quantum measurement, where the measurement apparatus determines the possible outcomes of a measurement.

The influence of the wider context on an object is called ‘top-down causation.’ Its omnipresence at all levels of complexity and in all fields of science disproves reductionism and physicalism. To me, top-down causation is also the best approach to explaining God’s action in the world. I have argued above that top-down influences may be immaterial, like our intentions or the laws of logic. How this immaterial realm interacts with the material world is not understood, but its influence is well substantiated. Some thinkers, among them John Polkinghorne, have suggested that this interaction might happen via the input of information.

Now, is it true that God never violates a law of nature when he acts in the world? As far as his everyday action is concerned, I am convinced of this. But what about special miracles, such as the resurrection of Jesus? Sometimes I ask myself what a team of physicists would have measured if they had been able to measure everything measurable during the resurrection of Jesus. Perhaps they would not have found any violation of the laws of physics. But since the resurrection of Jesus and also his other miracles foreshadow God’s new creation, it seems more plausible to me that these events transcend the laws of the present creation. Here we have reached the limits of what we can know . . .