Carl Sagan on Alien Abduction
Carl Sagan was captivated by the notion of life beyond Earth. Yet in this interview, conducted shortly before the well-known champion of science died in 1996, Sagan says that extraterrestrial intelligence is “a wonderful prospect, but requires the most severe and rigorous standards of evidence.” Sagan doubted that the various proponents of so-called “alien abduction” making headlines in the 1990s had met those scientific standards.
NOVA: Speculate for a moment on the parts of human nature, the commonality of believing in abductions, or aliens anyway, and the part of human nature that wants to search for other life forms in the universe.
Carl Sagan: I personally have been captured by the notion of extraterrestrial life, and especially extraterrestrial intelligence, from childhood. It swept me up, and I’ve been involved in sending space craft to nearby planets to look for life and in the radio search for extraterrestrial intelligence.
It would be an absolutely transforming event in human history. But, the stakes are so high on whether it’s true or false that we must demand the more rigorous standards of evidence—precisely because it’s so exciting. That’s the circumstance in which our hopes may dominate our skeptical scrutiny of the data. So, we have to be very careful. There have been a few instances in the [past]. We thought we found something, and it always turned out to be explicable.
So, a kind of skepticism is routinely applied to the radio search for extraterrestrial intelligence by its most fervent proponents. I do not see [in] the alien abduction situation a similar rigorous application of scientific skepticism by its proponents. Instead, I see enormous acceptance at face value, and leading the witness, and all sorts of suggestions. Plus, the contamination by the general culture of this idea.
It seems to me there is a big difference between the two approaches to extraterrestrial intelligence, although I’m frequently written to [to] say how could I search for extraterrestrial intelligence and disbelieve that we’re being visited. I don’t see any contradiction at all. It’s a wonderful prospect, but requires the most severe and rigorous standards of evidence.
NOVA: Could you please comment on the part of the quality of the evidence that is put forward by these so-called “abduction proponents.”
Carl Sagan: Well, it’s almost entirely anecdote. Someone says something happened to them, and people can say anything. The fact that someone says something doesn’t mean it’s true. Doesn’t mean they’re lying, but it doesn’t mean it’s true.
To be taken seriously, you need physical evidence that can be examined at leisure by skeptical scientists: a scraping of the whole ship, and the discovery that it contains isotopic ratios that aren’t present on Earth, chemical elements from the so-called island of stability, very heavy elements that don’t exist on Earth. Or material of absolutely bizarre properties of many sorts—electrical conductivity or ductility. There are many things like that that would instantly give serious credence to an account.
But there’s no scrapings, no interior photographs, no filched page from the captain’s log book. All there are are stories. There are instances of disturbed soil, but I can disturb soil with a shovel. There are instances of people claiming to flash lights at UFOs and the UFOs flash back. But, pilots of airplanes can also flash back, especially if they think it would be a good joke to play on the UFO enthusiast. So, that does not constitute good evidence.
"Precisely because of human fallibility, extraordinary claims require extraordinary evidence."