dodgy “appeal to mystery” worth nailing before we end this chapter runs as follows:
Why does the universe exist? You cannot answer this question. You must admit that it is a mystery that has not been solved. But if you do not know the answer to this question, then you cannot know that my answer—that it was created by God—is incorrect. You must admit that, for all you know, I'm right!
This is a bad argument. Suppose Sherlock Holmes is having a bad day. He just can't figure out whodunit. Does it follow that he cannot reasonably rule out certain suspects?
Of course not. Holmes may not know who did it, but he might still know who didn't. He might be able to pretty conclusively rule out certain suspects (the butler, for example, who has a cast-iron alibi). Similarly, someone unable to explain why the universe exists may nevertheless be able to use their powers of reason to rule out certain answers. Even a religious person will typically admit that there is overwhelming evidence the world was not created by an evil God. But then they must admit there could be overwhelming evidence that it was not created by a good God either.
This point is by no means restricted to religious beliefs. Manybelief systems often start with a mystery—they offer to explain what might otherwise seem rather baffling. Those who believe there's a family of plesiosaurs (snake-necked dinosaurs that went extinct sixty-five million years ago) living in Loch Ness, that the world was once ruled by aliens who still visit occasionally, or that there's a ghost in their attic will point to peculiar shapes on the surface of the loch, or the extraordinary ancient Nazca drawings in Peru (huge images visible only from high in the sky—some say they were created for the benefit of passing aliens), or exquisitely constructed crop circles, or the weird rattling sound coming from the attic, and say, “Explain that !” They challenge us to explain how such things were formed, or how or why they were made. When we can't, they conclude their beliefs, which we may be forced to concede do explain these things (even if rather badly), can't be so unreasonable after all. But of course, whether or not we can explain such things, we may still have excellent evidence that there is no family of plesiosaurs in living in Loch Ness (for a start, the loch has been frozen solid top to bottom many times over during the ice ages that separate us from the age of the plesiosaurs).
CONCLUSION
Mystery, as such, is no bad thing. Pointing out mysteries can be a valuable exercise—firing up our curiosity and getting us to engage our intellects. Nor is there anything wrong with acknowledging that some things may forever remain a mystery, and might even be in principle unknowable.
Sometimes it's also reasonable, when faced with a problem case for an otherwise well-established theory, to put it down as a mysterious anomaly. If on countless occasions an experiment has confirmed water boils at 100 degrees C, the fact that on one occasion it appeared not to may quite reasonably be put down to some unknown factor. If we can't discover what went wrong, it can be reasonable to just shrug and move on—putting the freakresult down to some mysterious problem with the set up (a faulty thermometer, perhaps).
It's also often reasonable, when we have a theory that works but we don't fully understand why it works, to say, “ Why this happens remains, for the moment, a mystery. But we know it does.” We might have strong evidence that smoking causes cancer, say, long before we understand why it does so.
So the appeal to mystery has its proper place, even in science. What I object to is the way in which the appeal to mystery is increasingly relied on to deal with what would otherwise appear to be powerful evidence or arguments against certain beliefs, particularly beliefs in the supernatural. Whenever mystery is erected as a barrier to rational inquiry, a barrier that says, “You scientists