Thinking about unidentified flying objects can be a useful exercise, whatever we believe about extraterrestrial life and its presence among us. If nothing else, it forces us to deal seriously with those perennial questions that are as useful to scientists and philosophers as they are to lawyers and politicians on congressional investigating committees: What do we know? How do we know it?
David M. Jacobs, an historian at Temple University, has been thinking about UFOs since his graduate school days, and what he has published about the subject over the years is among the most respected work on it. Mr. Jacobs believes UFOs are real—that is, that they are the interstellar transportation vehicles of an intelligent species of beings from another planet—and that a good deal of what is reported about them and their occupants is also real.
His chief concern is with the phenomenon of "abductions"—that is, the claims by a wide variety of people that they have been kidnapped by UFOs and subjected to various sorts of examination and manipulation by the aliens. Though Mr. Jacobs believes the abduction phenomenon is as real as UFOs themselves, he does not, like many people, view interstellar travelers optimistically. In fact, he believes they represent an imminent catastrophe for the human race.
The bulk of Mr. Jacobs' book is devoted to analyzing the nature of the aliens and their purposes,...