I’m interested in witches for two reasons.
First, it’s a good reminder of just how easy it is for people to believe completely false things. And also how much evil can result from these false beliefs.
Second, it brings out a general philosophical point that there’s no fixed divide between saying “X doesn’t exist,” and saying “X exists, but you have false beliefs about X.”
So, do witches exist? Well (even leaving aside wiccans), there are people who are accused of being witches, and some even agree that they might be:
“I don’t know if I killed that child. I don’t know if my juju goes out at night killing people. What can I do?”
These people exist, but they obviously do not actual have supernatural powers to produce death, infections, wealth, etc.
So we can either say that there are witches — but people believe a lot of false things about them –, or we can say that there are no witches at all (because one cannot be a witch without supernatural powers). Which option we take will depend more on pragmatics of language use than on any metaphysical facts.
This point is important for discussions of consciousness, free will, and qualia. I’ll flesh the point out more in the future, but the basic point is simply this:
When it turns out that everything is completely physical, we face a choice of whether we’re going to say that, e.g., consciousness exists and the dualist falsely believes that it’s non-physical, or whether we’re going to make it part of the definition of consciousness (freedom, qualia) that it’s non-physical, in which case it doesn’t exist.