A reader writes:
On last weeks Battlestar Galactica they had to wrestle with whether to commit genocide against the Cylons. Let’s posit that the Cylons are living beings rather than just machines. As we know they have tried to commit genocide against the humans. Would it be just under Catholic teaching to commit genocide against the Cylons? Might be good to get this decided before the Borg show up on our collective front door.
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Uh . . . I think you mean our non-collective front doors.
That being said, if (God forbid) we were living in the Battlestar Galactica universe, I would feel compelled to argue that Cylons (at least the humanoid ones) must be given the benefit of the doubt when it comes to whether they are living beings with rational souls–given all that we (or at least we, the viewers) know about them–and so the question of genocide becomes relevant.
Genocide is killing people because they belong to a particular genus (ancestry, race, kind). If you were to kill Cylons simply because they are Cylons then this would be genocide and it would be wrong.
However, if an entire species consists of aggressors then it is not genocide to kill all of the aggressors. The fact that they happen to constitute a species is extrinsic to the essential moral character of the act. What you are doing is eliminating aggressors, which is legitimate defense.
It may help to think of this in the small scale. Suppose one day a
flying saucer showed up above Earth and started using a mass driver to
destroy our cities. We would be morally justified in nuking the saucer
out of our sky. But suppose we discovered that the saucer had only
one occupant, and he was the last member of his race, so eliminating
him meant killing a whole species. He would not thereby possess an
exemption from legitimate defense. If he had a few more members of his
species helping him work the weapons, that wouldn’t change matters.
Neither would it if he had billions of fellow-helpers in a fleet of
saucers.
In real life, some argued during World War II that the entire population of Japan was functioning as combatants and so we could nuke Hiroshima and Nagasaki. This is not tenable, given human nature, but when it comes to the Cylons or the Borg, you really do have a species (or meta-species) that consists entirely or almost entirely of aggressors, and releasing a virus to kill the aggressors would be legitimate defense.
Of course, one would want to protect individual members of the species who are not aggressors (e.g., Athena and 7 of 9), but the mass elimination of aggressors, even when the aggressors form a single species or meta-species, would be legitimate in principle.
Please remember this during the next alien invasion.
P.S. Be careful, though, that you aren’t dealing with aliens like the Jaffa
or the Tok’ra, who may seem like aggressors but who actually can be turned into valuable allies.

