One of the central debates in the SETI community has been the question of whether or not we should engage in Active SETI (also known as Messaging Extraterrestrial Intelligence or METI). With the recent formation of SETI International and its expressed aims to discuss, debate and eventually engage in Active SETI, the debate has again arisen, particularly as those against METI raise concerns about the potential dangers of alerting an extraterrestrial neighbor to our presence.
Of course, there may be risk involved in messaging extraterrestrials. There is a high likelihood that any ETs who receive our message will be more technologically advanced than humans, because it is very unlikely that an extraterrestrial civilization with whom we make contact will be at the same technological juncture as humans, who have only been transmitting radio signals for about a century. We are early players in this game. But technological advancement does not necessarily equate to moral advancement, so there is no necessary reason to believe that ET will be altruistic, as opposed to bent upon galactic domination. Unfortunately, pretty much anything we think about this problem is conjecture, because we have yet to encounter a civilization more advanced than our own. But human history does not bode well for the idea that there is any correlation between technological advancement and moral advancement. We certainly need to be careful.
So what do we do? Do we hide our heads in the sand and hope nasty, advanced ETs never notice us? There actually is precedent in human diplomatic history for this approach -- it's called isolationism, which is a foreign policy approach in which the best interests of a nation are believed to be served by maintaining distance from the affairs of other countries. The U.S., as well as other countries, has tried versions of this approach throughout its history. In the early 20th Century, Woodrow Wilson attempted to keep us out of WWI and was even reelected on the slogan "He kept us out of war". In the end, the U.S. was unable to maintain neutrality and a position of relative isolation from the war in Europe and declared war on Germany. The U.S. again attempted to maintain neutrality and isolation in the 1930s, but this failed when Japan, in part in response to an embargo of U.S. oil (not really very isolationist) attacked Pearl Harbor.
The problem with isolationism is that it doesn't work very well on Earth -- our only example. Proximity and the unavoidable entanglements of economics and politics inevitably prohibit any one nation from maintaining isolation. Neutrality is easier to maintain, but even an entirely neutral stance vis-à-vis other nations is difficult. At some point, a nation will be pushed to take sides, particularly if it is attacked. And at that point, isolation comes to an end--often abruptly and without preparation on the part of the nation that was trying to keep its distance (think Pearl Harbor).
The alternative is engagement, or the active attempt to recognize that others, including potential enemies, are out there and that one way to mitigate potential threat is to exchange ideas, knowledge, and beliefs. Active SETI provides the potential to do just that--to engage an extraterrestrial other about whom we know nothing and begin the process of learning. If that extraterrestrial other is so much more advanced than humanity, then there are several possible outcomes. One is that it will be uninterested in this very low form of intelligence. Another is that it will be intrigued by our civilization reaching out. And, of course, another is that it will get wide-eyed with the lust for power and evaporate our planet. I'm not sure why ET would do this, but it is possible.
If ET actually has the technological ability to get here and wipe us out--let's say that ET is 500,000 years more advanced than humanity--then ET is going to do that if ET wants to do that. And what's the alternative? Should humans hide for half-a-million years in hopes that we have enough technological ability to defend ourselves? Oh, but, in half-a-million years, ET will be that much further ahead. In other words, those who strongly oppose METI are arguing that we should hide forever, because the fact is that we will never likely be more advanced than an alien civilization that is currently far ahead of us. Unless ET goes into some form of stasis or collapse, we won't catch up. ET from 500,000 years in the future may be just as capable of wiping us out as ET today.
None of this is intended to argue that there is no risk involved with METI. But it is my opinion that a good offense is the best defense. As we look to the stars and ask if there are others out there, letting them know that we are interested may be the best way to prevent some catastrophe based upon a lack of understanding. If ET wants to find other civilizations, then it will probably find us if it has the technical ability to do so. So we really can't hide anyway. Given that, we should craft a clear sense of how to represent ourselves and should have consultations among scholars, politicians, and others about how best to do this. And this does need to be an international effort -- there is no one representation of humanity that will suffice.
A good counter-argument to the point I am making is that throughout human history when a technologically superior civilization encounters a lesser one, it is always bad for the lesser one. This is true, but there are differences. Usually when such encounters happen, there is a subtext of colonization and exploitation of resources by the group with the superior technology. There is little reason to believe that an ET with the ability to get to Earth would have much use for our feeble resources (why not go after the rest of the solar system)? And the fact is that the contact will take place whether the less advanced civilization wants it or not.
There is no point in hiding our heads in the sand and hoping that an advanced ET just won't notice us until we are ready. And there is no way to know what "ready" means in any case. We are better off preparing. We should think now about what message(s) to send and how to convey the truth about our world, warts and all. There is always risk in taking an action, but it is important to remember that the decision for non-action -- or isolation with our heads hidden in the sand -- is also an action that has potential risks and consequences. If ET is advanced and nasty and doesn't like us, then there won't be much we can do about that, whether we engage in Active SETI or not. Active SETI has the potential to present ET with reasons not to dislike us.