"Any aliens advanced enough to hear our signals and have the realistic ability to contemplate a move against us can probably do the math: the likely threat of any alien civilization is from a practical perspective, zero, to them or us. The costs are too high, the barriers are too high, the risks are too remote, the rewards are too low."
This argument reminds me of economic theories that assume all humans are so-called "rational actors".
Even humans, which are in most ways like us and who we have some hope of understanding, do all sorts of things which most of use would consider "irrational", insane, self-destructive, and otherwise incomprehensible.
What justification could there be for assuming alien intelligences think in terms of costs, risks, or rewards? Or that they are in any way "practical" from some human's point of view?
Your argument also ignores the possibility that they have technologies or capabilities that might seem impossible (or even unimaginable) to humans of today (or perhaps of any time). Something that seems undoable to us, like FTL travel, might be possible or even easy for them. We don't know what we don't know.
This argument reminds me of economic theories that assume all humans are so-called "rational actors".
Even humans, which are in most ways like us and who we have some hope of understanding, do all sorts of things which most of use would consider "irrational", insane, self-destructive, and otherwise incomprehensible.
What justification could there be for assuming alien intelligences think in terms of costs, risks, or rewards? Or that they are in any way "practical" from some human's point of view?
Your argument also ignores the possibility that they have technologies or capabilities that might seem impossible (or even unimaginable) to humans of today (or perhaps of any time). Something that seems undoable to us, like FTL travel, might be possible or even easy for them. We don't know what we don't know.