Let there be no mistake. METI is a very different thing than passively sifting for signals from the outer space. Carl Sagan, one of the greatest SETI supporters and a deep believer in the notion of altruistic alien civilizations, called such a move deeply unwise and immature....Brin invited me to join a closed discussion group where this issue is examined and debated. The purpose of the exercise is to not just think more deeply about this issue, but to also raise awareness and possibly prevent a catastrophe (i.e. alien invasion). Essentially, Brin argues that METI needs to be strongly considered before any group or individual takes it upon themselves to shout out to the heavens. He is particularly concerned how some groups, including SETI, are dismissive of his concerns. His fear is that someone will unilaterally decide to start transmitting messages into the depths of space.
Sagan — along with early SETI pioneer Philip Morrison — recommended that the newest children in a strange and uncertain cosmos should listen quietly for a long time, patiently learning about the universe and comparing notes, before shouting into an unknown jungle that we do not understand.
I was unsure at first about whether or not I should join this group. As a contact pessimist I’m fairly certain that the fear about a METI approach is unwarranted -- not because ETI's are likely to be friendly, but because no one's listening. And even if they are listening, there's nothing we can do about it; any advanced ETI that's on a search-and-destroy mission would likely have the 'search' aspect figured out. I'm not sure how any civilization could hide in the Galaxy. Consequently, METI is somewhat of a non-issue in my opinion.
That being said, however, I did reach the conclusion that there is a non-zero chance that we could run into trouble should we change our approach from listening to messaging. For example, resident berserkers could be waiting, for what ever reason, for this sort of change in our radio signals. Perhaps they are waiting for a sign that we've passed a certain developmental threshold.
I think this argument is extremely weak and improbable, but it's not impossible; it should not be ruled out as a potential existential risk.
Which leads me to the precautionary principle. Since no one is listening, there is no harm in not sending messages out into the cosmos. Again, if a friendly ETI wanted to do a meet-and-greet, they should have no trouble finding us. But because there is the slim chance that we may alert a local berserker (or something unknown), we should probably refrain from the METI approach for the time being.
So, I took Brin up on his offer and I’ve joined the discussion group. We are currently considering the possibility of organizing a conference centered around the issue. I’ll continue to post about this topic as news develops. More information can be found here.