A few days ago I listened to a recent “Unbelievable” broadcast featuring a discussion on the possibility of intelligent alien life and how the discovery of such life might affect Christianity. It was an intriguing discussion between David Wilkinson and Mark Kidger, and it got me thinking once again about a topic I’ve often reflected on. (My new book on heaven features a chapter devoted to the possibility of ETI and how an intelligent alien species might fit into a redeemed creation. I’ve addressed the topic of ETI at various other times in the past, most notably in my articles “Would intelligent aliens present a problem for Christianity?”, “‘And if there’s life on other planets…’ Reflections on God and E.T.“, “‘And if there’s life on other planets…’ Reflections on God and E.T. Part 2“, “The Nebular Incarnation Thought Experiment,” and “Carl Sagan’s Old Time Religion.”)
So now I return to the topic once again. This time I do so to offer a modest reply to Fermi’s Paradox, an idea first proposed by physicist Enrico Fermi. Fermi begins with the observation that there have been habitable planets orbiting stars like our own for millions of years prior to the appearance of human beings on the scene. From this it follows that if there were advanced alien civilizations elsewhere in the galaxy they would have arrived at our planet by now. The fact that they haven’t suggests that there are no alien civilizations.
It’s an interesting argument, but it sure ain’t a slam dunk. For one thing, it assumes a picture of alien arrival and presence (e.g. the typical Hollywood landing on the White House lawn) which strikes me as quite wrong. Contrary to Fermi, I would argue that the lack of evidence for ETI is not evidence that there are no ETI civilizations in our galaxy. I am, in short, offering an undercutting defeater.
First off, what’s an undercutting defeater? Here’s an example. The other day I was driving along in the evening when I saw a powder pink Ford Fusion. Pink? I thought to myself. That’s a weird color for a car! (No offense Mary Kay sales ladies.) Then a block later I saw a Nissan Rogue. And lo and behold, it also was colored powder pink. Double weird! I thought to myself. (Okay, I admit, I didn’t really think “Double weird.” I simply added that detail for dramatic effect.) Then as I pulled up beside the Rogue I realized that the “pink” color was, in fact, the illumination of the setting sun against a white paint job. The car was really bone white and the lighting merely made it seem pink.
The close up view of the Rogue as white presented me with a rebutting defeater for the Rogue being pink. But what about the Fusion? I didn’t have any direct evidence that that car (now long gone) was white and so I had no direct rebutting evidence that it wasn’t pink. For all I knew, it really was pink and a close up would have confirmed that fact. However, the realization that the setting sun made white cars look pink did provide an undercutting defeater for belief that the Fusion was pink. In other words, this evidence defeated my justification for believing the car was pink. It might still be pink, but I had lost the evidence to think it was pink.
Now for Fermi’s paradox. I’m not proposing to provide evidence that aliens have visited earth (a direct rebuttal of Fermi’s argument). Rather, I would argue that the evidence, such as we have it, is consistent with aliens having visited earth. Just like the pink color of the car is consistent with its being white, so the apparent absence of alien presence is consistent with aliens visiting earth.
So what is the argument akin to the realization that the sun makes white cars look pink?
Well let’s return to human civilization for a moment. Human beings have been on this planet as a species for a couple hundred thousand years. However, it is only in the last 150 years that we have begun to appreciate the importance of wildlife preservation. I say “150 years” as a rough approximation because the first national park preserve — Yellowstone National Park — was established in 1872. Since that time human beings have become increasingly aware of the deleterious effect that we can have on an ecosystem (think, for instance, of the maxim “Don’t feed the wildlife” and the goal to minimize one’s “ecological footprint”). A film like Wall-E provides a sobering warning about such issues. (For a trailblazer in this respect see children author Bill Peet’s wonderful 1970 book “The Wump World.”)
With this evidence in hand, it is reasonable to suppose that any super-advanced alien civilization millions of years older than our own would likely have a much fuller and finer appreciation for the need not to feed the wildlife and to minimize one’s ecological footprint. (By contrast, it is likely that civilizations with no appreciation for ecological impact — civilizations like that memorably depicted in “Wump World” — would self-destruct long before they got to the point of interstellar travel.) And that suggests the more advanced a civilization, the less likely we should expect that civilization to make us aware of its presence. Ms. Goodall may have interacted with the chimps, but primatologists no longer allow such behavior. ETI may have once interacted with other civilizations but by the time they arrived on earth they’d wised up. Thus, for all we know, our third rock out from the sun may be a wildlife preserve. Perhaps the development of life on our planet has been under observation for thousands — or millions — of years.
I have no conviction about whether this is the case (though I admit I’m inclined to think it isn’t). But that’s not the point. Instead, the point is that this realization that it is quite likely that advancing civilizations would gradually seek to minimize their impact on ecosystems provides an undercutting defeater to Fermi’s paradox.
