PARANORMAL PHENOMENA ARE creatures or occurrences that cannot be explained scientifically. Sightings of unidentified flying objects (UFOs), reports of alien abductions, mental telepathy, ghosts, and miracles all fall into this category.

Some people say that such phenomena are real, whether or not science can explain them. Others argue that if something is unexplainable by science, it must not be real. These two sides—believers and skeptics—engage in heated debates over whether reports of paranormal experiences are the product of hallucinations or something more substantial.

Meanwhile, researchers into paranormal phenomena continue to seek explanations. As Jerome Clark says in his book Unexplained!, "The three hardest words for human beings to utter are I don't know. We demand an accounting for every claim or experience, and when no accounting is available, someone will invent one for us." Consequently scientists and psychologists have come up with a variety...