"Supernatural" is a self-refuting concept. It's literally meaningless, since describing any "supernatural" event must always lead back to appeals to the natural. Why? Because supernatural events are detected by people, and people are natural. Therefore, anything they can detect, regardless of the cause, must also be natural. Even hallucinations are natural because they involve real changes in neuron firing patterns.

So if you say, for example, that ghosts exist, and they're not hallucinations, then you will eventually have to cite physical evidence. But physical evidence is natural! Therefore ghosts are a natural hypothesis!