The case for Autointerdiction.

[Drashner1]

1) Sure, we have the means to destroy our civilization and the odds are nonzero. But by creating a population that would not be destroyed you create a population that would have less incentive to refrain from using it. Good for the human race as a whole, in terms of survival - but not good for the people on the original world who are making the decision about whether to let anyone leave. IOW, even if you increase the odds of civilization surviving, letting anyone out would be lowering the odds of your own descendants or your own home surviving.

Firstly, with biowarfare you can already do this in principle. Inoculate your population and kill off everyone else with a disease. I don't see any real difference myself - dead is dead.

Secondly, this seems to me to be an excellent reason to make an effort to see to it that your descendents (at least some of them) are among those living elsewhere.

Thirdly, if you've got the tech to send significant numbers of people elsewhere, you can probably protect Earth from most threats they could pose, or at least have the means to strike back - so the issue of distant populations being able to act with impunity doesn't really exist. It may take a while for retaliation to arrive, but it can arrive if people are determined about it.

Coming at this from another direction, if you have many different colonies all over the place, it is not in any of their interests for one or a subset of their number to go around destroying any of the others. Doing so would likely result in retaliation in kind. So a form of MAD might be in effect.

2) Sure there's already a chance of being invaded by others on earth. Why would that make it a good idea for anyone to make the chances worse?

Why would anyone actually want to invade? Much of SF notwithstanding, planets are really not great places to live for any number of reasons. Odds are that any kind of serious colonization project would involve some form of space habs making use of resources in much shallower gravity wells than Earth. To such people, mucking around in a deep gravity well, while dealing with earthquakes, hurricanes, tornados, and various parasites and pests that their ancestors might have left behind would seem likely to seem rather pointless.

And again, if you are going to be bothered by being invaded, then the odds seem much greater that it will happen from a nearby nation. Does that mean you should take pre-emptive action to eliminate everyone else? Some might think that way, but most don't seem to.

3) Sure, there's a significant risk that a GRB, supernova, colliding neutron star, etc, could sterilize earth. But the decisions are being made in the interests of existing nations, not in the interests of the survival of life as a whole. Adding human beings to the set of potentially hostile forces away from Earth is still adding to the set of potentially hostile forces that can attack Earth. The calculus of nations doesn't care if someone *ELSE* survives.

It's a virtual certainty that one or more of those natural events will happen and would destroy existing nations along with everything else (assuming existing nations still exist by the time we get colonizing anyway) and none of those natural events can be reasoned with, nor can some of them be defended against without putting humans elsewhere, at least with any tech or lifestyle choice we foresee now. Humans living elsewhere can be reasoned with and defended against, therefore they are the lesser threat.

4) Yes, eventually Earth will be destroyed. But A, that's a long time from now, and B, considering the time scales involved the narrow-sighted little buggers probably see earth being subject to destruction in 1% or less of the time that would take as a result of releasing humans from here. So, from the 'Dr. Strangelove' perspective Earth survives 100 times as long if they don't let anyone go, and the fact that this dooms humankind to extinction is merely collateral damage.

So the 'narrow-sighted little buggers' find multi-million or billion year timescales too long but thousands or tens of thousands of years too soon. Very specific narrow sighted little buggers you're postulating here You're also falling into the logic trap that anyone and everyone in a position of leadership is of a mindset to think this way and that this is an inherent property of all leaders everywhere forevermore.

5) Creating a real, definite, new existential threat in order to deal with a hypothetical and potentially nonexistent threat? Let's ask Dr. Strangelove again. The answer isn't just no, it's Hell no.

It's not a real or definite threat - it's just as hypothetical as aliens invading or destroying Earth. So why is one hypothetical more 'real' than another?

I hate this, but if you take the short-sighted, narrow view of preserving Earth and her existence over all else, the logic is pretty damn compelling. And our decision makers have always been all about short-sighted and narrow.

Firstly, an argument can be made that never leaving the Earth is likely to result in our destruction via human factors that could act much more quickly than natural ones.

Second, it is already demonstrated that natural factors can (and eventually will, unless we do something about it) destroy or severely damage our civilization and species - vs - the potential of other human cultures doing so (while presuming that we would not be able to do anything about it in one form or another, which doesn't necessarily follow).

Third, the idea that decision makers have always been all about short-sighted and narrow, while popular in Western civilization for some reason, is demonstrably not true. The founders of the US were certainly trying to design something to last over a significant historical time frame. The builders of the pyramids or the Great Wall of China tackled projects that took generations, at least. Same for the builders of the great cathedrals in Europe. Probably plenty of other projects and examples elsewhere on the planet as well.

Taking the view that a particular common mindset in the here and now is the only way people can or have ever thought isn't supported by the evidence. For that matter, thinking that that mindset is the only way that current leaders think probably isn't supported by evidence either.

Todd