If there is a supernatural element to our universe (or beyond), how could we possibly know it?
1. I often use the term “intangible naturalism” as it could refer to something wholly natural that is beyond our current ability to understand - whether because of a lack of knowledge or because our brains are not made to understand it. An example would be electricity. Now it is considered a product of the natural universe, but perhaps sparks and electric currents were examples of “intangible naturalism” 1,000 years ago. Anything “supernatural” or “intangibly natural” at this current point in time are indistinguishable. Perhaps we will discover how the “intangibly natural” fits into the chain of cause and effect in the future. Perhaps we will not. Where would one decide to call something currently not understood supernatural? The transition from “intangibly natural” to “supernatural” is not one that we are equipped to make.
2. The only difference between natural and allegedly supernatural elements of existence is predictability. Once again, think of electricity. It is natural since it predictably acts certain ways given certain causal elements. But think about what it does. Things move without being pushed, visual sparks shoot out of our hands when we touch, lightning splits the sky - this is the stuff of fairy tales. Except that we can predict it.
3. Anything supernatural that acted predictably would not be supernatural! It would be natural. Another way to think about this besides predictability is connectedness. Everything natural is affected by other natural elements and affects other natural elements. It’s all a dance of cause and effect played out in motion through time. Supernatural elements are disconnected from this. If they were not, they would be natural. Evidence is based on the connections of cause and effect, so we cannot use any natural evidence to support supernatural conclusions. The supernatural will not obey our attempts to observe it or else it would be natural, therefore there is no way to prove whether supernatural elements exist or do not exist.
4. It makes no sense to complain about a lack of proof for the supernatural. However it also makes no sense to put forth specific supernatural explanations for anything as that would require many wholly arbitrary presuppositions about the supernatural. For instance if we say that “God cured my sickness”, then why not say “God created the memory in me and others that I was sick, but I never really was.” Why is the first more plausible than the second? If it’s because of less supernatural involvement then, as I’ve argued elsewhere, why not assume there is no supernatural involvement? Also, if we are describing supernatural in terms of quantity, where do we get those ideas of quantity? We get them from the natural world which the supernatural does not have to resemble in any way. Which is easier for God - to cure a cold or to create 1,000 new universes? So to argue a supernatural explanation, whether God or anything else, is to place many assumptions on to that supernatural hypothesis.
5. But once again, to say there is no such thing as the supernatural because of a lack of evidence is also problematic. Reliable evidence would make it natural!
Conclusion - there could be supernatural elements of our existence, but we can never know it. It would lie outside the realm of evidence, so we cannot complain of a lack of evidence for it. However, to put forth specific ideas about supernatural explanations, and to insist they are right, makes even less sense.