> You're neglecting many reasons extra terrestrial life may pose a threat.
I'm ignoring the ones that are so far in the realm of speculation with today's knowledge they could go either way. For example the argument "they may want to live here" could be valid, but there is just as much reason to believe that any space-faring civilization bent on aggressive expansion should already have significant terraforming capabilities, thereby making uninhabited worlds an easier target. The second issue with this particular argument is the probability that Earth would be a perfect environment for a given alien species: We simply don't know how many earth-like planets are out there. If there are many, the probability of compatibility would be high, but so would the number of less-problematic alternative planets to choose from. If there are few, chances are our world needs to be terraformed anyway in order to make it habitable, meaning there is no reason to choose it for colonization over many other (uninhabited) candidate planets in the first place.
> wiping out humanity probably won't be particularly challenging for them
Nobody said it would be.
> Also, your second point is invalid, territorial reasons are not void. We may pose no threat now, however a technologically superior civilization may conclude we pose a future threat, and so wipe us out now before we can become one.
That's a misunderstanding. I did categorize reasons like this one as spiritual or "other", because it's not rooted in a concrete need to eliminate us right away. Never mind the categorization: yes, that's a possibility I tried to hint at with the paragraph "There are still some nefarious reasons why an outside civilization may attack us [...] There are certainly other reasons we can't even think of yet."
> Also, the old 'dangerous biology from somewhere else!' is almost entirely null and void, organisms are adapted to their environment, they usually pose negligible risk to any other environment already inhabited by biological organisms. This is why, for instance we don't treat organisms from thermal vents as 'oh noes, biohazard material'.
I really dislike your polemic style, so let me answer in kind: the caretakers of countless pacific islands and other isolated places who are currently struggling to protect habitats from invasions of foreign species would probably like to subscribe to your newsletter. Little did they know how unfounded their concerns had been until you came along.
I'm ignoring the ones that are so far in the realm of speculation with today's knowledge they could go either way. For example the argument "they may want to live here" could be valid, but there is just as much reason to believe that any space-faring civilization bent on aggressive expansion should already have significant terraforming capabilities, thereby making uninhabited worlds an easier target. The second issue with this particular argument is the probability that Earth would be a perfect environment for a given alien species: We simply don't know how many earth-like planets are out there. If there are many, the probability of compatibility would be high, but so would the number of less-problematic alternative planets to choose from. If there are few, chances are our world needs to be terraformed anyway in order to make it habitable, meaning there is no reason to choose it for colonization over many other (uninhabited) candidate planets in the first place.
> wiping out humanity probably won't be particularly challenging for them
Nobody said it would be.
> Also, your second point is invalid, territorial reasons are not void. We may pose no threat now, however a technologically superior civilization may conclude we pose a future threat, and so wipe us out now before we can become one.
That's a misunderstanding. I did categorize reasons like this one as spiritual or "other", because it's not rooted in a concrete need to eliminate us right away. Never mind the categorization: yes, that's a possibility I tried to hint at with the paragraph "There are still some nefarious reasons why an outside civilization may attack us [...] There are certainly other reasons we can't even think of yet."
> Also, the old 'dangerous biology from somewhere else!' is almost entirely null and void, organisms are adapted to their environment, they usually pose negligible risk to any other environment already inhabited by biological organisms. This is why, for instance we don't treat organisms from thermal vents as 'oh noes, biohazard material'.
I really dislike your polemic style, so let me answer in kind: the caretakers of countless pacific islands and other isolated places who are currently struggling to protect habitats from invasions of foreign species would probably like to subscribe to your newsletter. Little did they know how unfounded their concerns had been until you came along.