  The METI risk problem refers to the uncertain outcome of sending
transmissions into space with the intention of messaging to extraterrestrial
intelligence (METI). Here, I demonstrate that this uncertainty is undecidable
by proving that that the METI risk problem reduces to the halting problem. This
implies that any proposed moratorium on METI activities cannot be based solely
on the requirement for new information. I discuss three policy resolutions to
deal with this risk ambiguity. Precautionary malevolence assumes that contact
with ETI is likely to cause net harm to humanity, which remains consistent with
the call for a METI moratorium, while assumed benevolence states that METI is
likely to yield net benefits to humanity. I also propose a policy of
preliminary neutrality, which suggests that humanity should engage in both SETI
(searching for extraterrestrial intelligence) and METI until either one
achieves its first success.
