More criticism of self-appointed messengers to the stars, from David Brin and Robin Hanson. We know how well contact has worked between members of the same species right here on Earth - imagine Chumash graduate students on the shores of pre-contact California saying, "Hey, we should build big signaling fires in case there are any foreign people sailing up the coast in big ships, to make sure they don't miss us." And the potential problem we face is of a whole different order. The Chumash faced conspecifics with better technology. The problem we're talking about now is the appearance of great white sharks or microorganisms with better technology. Is this paranoid? One objection is "no one/nothing will hear it anyway, so stop worrying." Then why are they wasting taxpayer money on these little exercises in the first place?
To be perfectly clear, the argument here is not about the implausibility of life elsewhere in the universe; it's quite the opposite. By all means we must continue exploring space and looking for life, and this includes SETI, and even sending interstellar probes out in our lifetimes. But if you believe in the possible of sentient life elsewhere in the universe, and you accept natural selection as the path by which life arises, then there is no room for argument: these messages should stop immediately.