it's a series hypotheses that tries to explain our 'uniqueness' as an organism.
it basically revolves around something called 'the great filter', which would act as a barrier for a lot of lifeforms to progress.
the first version is that we as humans are beyond the great filter, but entirely alone ( with the filter being something like the preservation of existing knowledge).
the second is that the great filter is beyond us, but there are multiple animals who bridged it also. in this case, we are not special, but merely ahead of the curve.
the third is that the great filter is ahead of us. multiple civilisations would have come to the point we have, but were unable to go further. the filter in this case would likely be inter-planetary colonization.

it's mostly a philisophical debate, and has no real scientific basis.

>>17077493
Thanks, anon. Truly contributing to x with something worthwhile.

I believe the filter is responsibility concerning the weaponization of natural phenomenon

>>17077509
could be.
i personally believe that the filter is nuclear power, and we are one of few beings that didn't fuck up entirely. if you look at the cold war, we were really fucking close to a global extinction phenomena.

Here's an article that explains it pretty thoroughly
http://waitbutwhy.com/2014/05/fermi-paradox.html