Abstract

My focus is on the contemporary astrobiological activity of Messaging ExtraTerrestrial Intelligence (METI). This intentional astrobiological signaling typically involves embedding digital communications in powerful radio signals and transmitting those signals out into the cosmos in an explicit effort to make contact with extraterrestrial others. Some who criticize METI express concern that contact with technologically advanced extraterrestrial life could be seriously harmful to Earth or humanity. One popular response to this critique of messaging is an appeal to causal impotence sometimes referred to as the ‘Barn Door’ Argument—we are already engaged in many other detectable activities not intended for cosmic communication. If the Barn Door Argument is correct, then those who engage in messaging arguably have a moral excuse. They are permitted to continue messaging because there is no point in abstaining. I develop three ways in which the claim of causal impotence in the Barn Door Argument could be understood. I evaluate each of these in turn and demonstrate that only one is appropriate to contemporary messaging. However, this interpretation does not generate the moral excuse on which the proponents of the Barn Door Argument rely; thus, the argument fails. Finally, I entertain and respond to candidate objections.