Is it possible to have empirical evidence for the existence of God? One sometimes hears statements to the effect that this is impossible, since God himself (if he exists at all) is immaterial. How could we have evidence, by means of the senses, for the existence of a being who is utterly immaterial? Then, too, most theists would say that God is very different from ourselves. Would it not be impossible to have empirical evidence for God’s existence, given that he is unlike us and that we therefore cannot predict his motives? If this being is altogether different from ourselves, both in the sense of being immaterial and in the sense of having a mind far above ours, perhaps we should not even consider the possibility of knowing him by means of evidence in the material world.
1) We could have empirical evidence for the existence of God because God is a causal agent.
I answer, first, that empirical evidence for the existence of God is possible, because if God existed he would be a causal agent. It may come as a surprise to some physicalists, but their knowledge of the existence of causal agents around them does not depend in any crucial way on the premise of physicalism. If you are a physicalist, you believe as a matter of fact that your friends and your parents are purely physical entities, but you do not require a statement of that metaphysical commitment as a premise in order to know that they exist in the first place. You no doubt learned, rationally, that other beings like yourself existed long before you held to any particular metaphysical theory; your justification for believing in their existence was founded on your observation of their actions. From observation of another being’s behavior and its results in the world, it is possible to conclude that the best explanation is the existence of, say, your best friend, who has causal powers in the physical world. Again, you may believe as a matter of metaphysics that he would not have those causal powers if he were not a physical being. You may, as a philosopher, reject interactive dualism. But the rejection of physical/non-physical interaction forms no necessary part of the inference to the best explanation for the existence of other agents. This is why explicit non-physicalists as well as those who simply have no opinion on the matter can be justified in believing in other minds. Whatever the metaphysical underpinnings of those other minds, they appear to exist because of what we see them doing. We have conversations with them, see them altering physical reality in a seemingly intentional way, and so forth.
The point is perhaps even more vivid when it comes to Internet friends. In the 21st century, many of us have a great number of friends and acquaintances whom we have never seen. The inference to their existence sometimes is more conscious than it is for in-person friends. There are robots on social media set up to mimic human agents. We use tacit algorithms (and Facebook uses explicit algorithms) to try to decide which “people” are not really “people,” and we reasonably believe in many cases that we are interacting with real people at long distance, by electronic means. We can tell that they exist as real agents like ourselves by noting the nature of their communications, even though we have never seen or touched their physical bodies or even Skyped with them.
If God exists, he is an agent with causal powers in the world. This is true even on a fairly minimal version of theism, though as I shall argue below, it is not necessary to restrict ourselves to a minimal version of theism in our inquiry. An agent with causal powers in the physical world is able, ex hypothesi, to make a difference in the physical world. It is therefore possible in principle that we could notice and detect this causal activity, just as we do with other agents. The fact that God is immaterial does not make this epistemically impossible, because the assumption of materialism is not required for the inference to the existence of other minds.
2) We could have empirical evidence for the existence of God, since God would have supernatural powers of communication.
Not only would God, if he exists, have causal powers in the world generally. He would also have the power more specifically to communicate in ways that lie beyond the powers of the natural order, and such communication would constitute empirical evidence for his existence. Atheists will sometimes tacitly acknowledge this point when they ask why God does not do something truly obvious, such as spelling out a message in the stars. That very suggestion involves the admission that such an explicit message would be empirical evidence for the existence of God.
If God exists, then he (presumably) had something to do with the existence of mankind and therefore might wish to communicate with man. Of course, we might not know precisely how he would wish to communicate with man or even for certain that he would wish to communicate. But communicating with other minds is the kind of thing that intelligent agents do, and if God made us (either directly by creation or indirectly by some sort of guided process), then there is at least some probability that he would wish to communicate. It need not even be an especially high probability in order for us to consider that God’s actions are not simply randomly selected from all the possible things he could do. Acts of God that would convey a message that could be comprehended do not have identical probability to communicatively pointless actions such as mixing up molecules on an uninhabited planet.
Even though God would be far different from us and far above us, it does not follow that his actions would always be incomprehensible or meaningless to us. An adult’s thought processes are far above those of a young child, but the adult knows that he must use language or gestures that the child will understand if he is going to communicate with him.
We do have some idea of what events in the world will and will not convey any content to human minds. What appears to us to be just like the outcome of unguided chance or natural processes does not usually convey content. If God exists, he presumably knows that we won’t recognize a message from him just because we see a dandelion growing on this patch of lawn rather than that patch of lawn. But we might be able to see that the existence of any dandelions at all showed evidence of God’s existence. If God wanted to communicate to us that he designed living things, he would have to make them sufficiently like those things that we ourselves design for us to recognize the pattern. For example, we human agents use the concept of function, and we make detailed mechanisms for the purpose of fulfilling a function--the adequation of means to ends--in our own designs. We also have the capacity to recognize the adequation of means to ends in a natural object. If the existence of such objects were also (by investigation) highly improbable given only the operation of natural processes, then this would be a recognizable way for God to communicate his existence to man.
Similarly, if someone comes along who claims to be a prophet, who does not appear (in other ways) to be simply insane, who lives a morally admirable life, and who claims that what he says is a message from God, it is at least possible that this person’s ministry constitutes an attempt by God to communicate with man. But at that point, to distinguish the alleged prophet from a charlatan or a deluded person, God would probably need to perform some sign that would show us that this is indeed his messenger.
We can imagine circumstances in which that would happen--verified miraculous healings, for example, or a resurrection from the dead. Such a nexus of events could in principle constitute empirical evidence for the existence of God.
3) We could have empirical evidence for the existence of God because we can investigate particular religions that make particular claims.
There is a persistent, incorrect idea in the philosophy of religion that one can examine particular religious claims only after one has rationally concluded that a more minimal version of theism is true. We supposedly could not be rationally convinced of the truth of Islam or Christianity unless we already had enough other evidence to believe that some God or other exists.
Of course, it would be quite a good thing for the theist if he did have independent evidence for theism, broadly construed, and it is entirely possible, even plausible, that such evidence is available. But the insistence that an inquirer must accept independent evidence for broad theism in order to be justified in believing a particular version of theism is epistemologically wrong. To see that this restriction is misguided we need only look at our rational practice in other situations. We do not have to believe on independent grounds that some Irishmen or other exist before we can conclude that a specific Irish neighbor, Sean Donovan, exists. In fact, if one were previously ignorant of geography and history, one might discover the existence of Ireland and Irishmen for the first time by way of conversations with Sean Donovan and his claims to have come from that island. It is possible to discover that some Irishmen exist by means of learning that particular Irishmen exist rather than first learning the generic fact, “There are Irishmen” and then separately concluding that Sean is one of them. This is true in numerous other situations. We may rationally learn for the first time of a type of job or hobby by conversing with a particular person who has that job or hobby.
In the same way, there is no rational block to our learning that some God or other exists by acquiring evidence for the existence of the God described by a particular religion. This point opens up a great many possibilities for empirical confirmation and disconfirmation, since some religions make highly specific claims that could, at least in principle, be supported or disconfirmed. Did Joseph Smith see the angel Moroni and receive golden plates from him? Was Mohammed a prophet? Did God choose the people of Israel and lead them out of Egypt in the Exodus? Did Jesus of Nazareth rise from the dead? We can look into such claims and see whether there is evidence to support them. If there were such evidence, this would in and of itself be evidence for the existence of God--namely, the God who performed the action or appointed the person in question.
We must bear in mind that the claims made by particular religions are sometimes historical. If Jesus of Nazareth rose from the dead, this happened at one particular time in past history. It is not as though one can go into a laboratory and ask Jesus to rise from the dead every day in front of a camera. It is of the very nature of such a miraculous confirmation that it is unusual and takes place against a stable natural background, so that it can be recognized as the act of a supernatural being. This means that God’s actions, when they are of this historical kind, cannot be investigated by the same methods by which the laws of chemistry can be investigated. But this does not make the evidence for them (if there is such evidence) non-empirical, spooky, or subjective. In this respect, these alleged events are like any other unique historical event. You cannot put Caesar in a test tube in order to conclude that he was murdered by conspirators in the Roman Forum. Caesar’s death was an event that happened at one time in the past, but it has left empirical traces in the form of historical documents, and we can read those documents, compare them with one another and with other information, and check out their claims to accuracy. This is the nature of historical investigation through testimonial evidence.
I am not arguing here for the truth of any particular, historical religious claim but merely arguing that, in the nature of the case, it is possible for such a claim to be confirmed by evidence available to our senses.
It is artificial to put the existence of God into a separate box from other existence claims, treating it as immune both to confirmation and to disconfirmation. The theist (or the person investigating the claims of theism) is not required to assume that God, if he were to exist, would be incapable of making his existence known to finite creatures. In fact, since various religions claim that God has made his existence known, such an assumption is question-begging against those truth-claims. Since the existence of a God who both can and does reveal himself in the physical world is possible, it is philosophically untenable to exclude a priori the existence of empirical evidence confirming his existence.
About the Author: Lydia McGrew is a widely published analytic philosopher, home schooling mother, blogger, and the wife of philosopher Timothy McGrew. She received her PhD in English from Vanderbilt University in 1995 and has published extensively in the theory of knowledge. She specializes in pure formal epistemology and in the application of formal epistemology to the evaluation of testimony and to various topics in the philosophy of religion. Her philosophical articles have appeared in such journals as Ergo, Philosophical Studies, the Journal of Philosophical Research, andErkenntnis. She and Timothy McGrew co-wrote the article on the resurrection of Jesus for the Blackwell Companion to Natural Theology, and she wrote the article on historical inquiry for the Routledge Companion to Theism. She has recently published Hidden in Plain View: Undesigned Coincidences in the Gospels and Acts, which defends the reliability of the New Testament using a long-neglected argument from incidental details.