What justifies the astrobiologist's search for post-biological or machine-intelligence in outer space? Four assumptions borrowed from transhumanism (H+) seem to be at work: (1) it is reasonable to speculate that life on Earth will evolve in the direction of post-biological intelligence; (2) if extraterrestrials have evolved longer than we on Earth, then they will be more scientifically and technologically advanced; (3) superintelligence, computer uploads of brains, and dis-embodied mind belong together; and (4) evolutionary progress is guided by the drive toward increased intelligence. When subjected to critical review, these assumptions prove to be weak. Most importantly, evolutionary biologists do not support the idea that evolution is internally directed toward increased intelligence. Without this assumption, justifying the search for ET more intelligent than earthlings is anaemic. Nevertheless, one can still hope that in the near future we will be communicating with new neighbours in the Milky Way. Can sheer hope inspire science?