Professor Frink: Yes, over here, n’hey, n’hey. In Episode BF12, you were battling barbarians while riding a winged Appaloosa, yet in the very next scene, my dear, you’re clearly atop a winged Arabian! Please do explain it!
Lucy Lawless: Uh, yeah, well, whenever you notice something like that… a wizard did it.
Frink: I see, alright, yes, but in episode AG04-
Lucy Lawless: Wizard!
— The Simpsons, “Treehouse Of Horror X”
The supernatural, whatever exists outside the natural, is the last refuge of the intellectual scoundrel. Theist apologists like William Lane Craig dress it up with jargon such as the “non-contingent” but it’s all the same. Snake oil marketeers, paranormal aficionados, and others make liberal use of the concept as well: it’s the place where ghosts are hiding that no camera can reach (except when they do); it’s the carrier for psychic vibrations undetectable by means other than a special kind of receiver (a credulous person). Skeptics investigate some of these claims, but I wish to speak more basically: does the word “supernatural” have any coherent meaning at all?
Google tells me the word has this meaning: (of a manifestation or event) Attributed to some force beyond scientific understanding or the laws of nature. I’m going to assume the first part of this definition means beyond that which science is capable of parsing, because loads of things are momentarily beyond scientific explanation without anyone describing them as “supernatural”, such as the bizarre readings now being received from the Voyager 1 spacecraft. The definition is essentially, that which is outside the natural. I can’t fathom anything to which this could apply, even theoretically. Every specific claim that mentions or relies on “the supernatural” also invalidates the definition completely.
Nature is the universe. The set of things that can be said to exist, to have existed, or that will exist. If, for example, a god exists, then it is some sort of a thing that has properties and behavior, then it is a part of the things that exist and is thus natural. This is true whether or not we can detect it. Distant galaxies were perfectly “natural” a thousand years ago before people could detect or understand them. And what can it mean to be “outside” or “super-” to nature? Outside is a preposition that only has a literal meaning in physical space. It is a relation of one object or entity to another object or entity. Objects are items that occupy space within nature. One might try to argue the meaning is metaphorical, but that’s cheating: it presumes that the elements of the metaphor have some of the same properties, in this case nature and supernature. It’s question-begging to simply imply nature can be defined as an object to which something can be inside or outside of, and it contradicts the ordinary definition of that term (the things that exist). As it is, prepositions like “outside-of” refer to space-time. Any new meaning must be specified and explained. None have been.
It could be that things called supernatural are merely unexplained natural things. Phenomena such as weather and disease were once thought to be the work of gods and demons, but this was fallacious thinking at best which no sensible person should engage in, no matter the unexplained phenomena. Today scientists are content to call the unknown, unknown. Not the work of wizards, and so the word “supernatural” does not have this role either.
Every specific invocation of the term actually precludes any coherent definition. Let’s start with gods, of if you prefer, God. Creator Gods are all definitively natural. They interact with atoms and people and planets. But those things are made of matter, they are bits of nature. Things that can interact with matter are also, by definition, energy or matter, which is to say, natural. Miracles are all natural phenomena, invisible Godly meddling with water or microbes or moons, much the way humans do but more vaudevillian in the telling. Surely the “supernatural” the thing “outside” of nature can’t do the the sorts of things done by the natural, inside of nature?
Similarly if there were psychic powers, they would surely be a capability of neural tissue because psychics who receive “messages” gain awareness through their brains, the place awareness of any kind happens. A signal capable of causing a wiggle or firing of a neuron to later be understood as a message would also be detectable to an artificial detector designed to replicate the bit of neural tissue doing the receiving. We’ve had no trouble at all building sensors that can see, hear, feel, detect temperature, acidity, not to mention huge swaths of the electromagnetic spectrum our organs can’t detect. If there were “psychic” powers, there certainly would be nothing supernatural about them, just heretofore unknown, like every other natural mystery waiting for us.
I therefore conclude the term “supernatural” has no coherent literal meaning. It is a word without a referent. It’s like saying “the four-sided triangle” or “the opposite of pen”. Lexically, it exists to embody the argument from ignorance fallacy.