Why does there have to be 'one' great filter... I think it's more a 'tiered' system... I mean on any given planet getting to eukaryotes is difficult..once you d

Why does there have to be 'one' great filter... I think it's more a 'tiered' system... I mean on any given planet getting to eukaryotes is difficult..once you do, you've made it past 'a great filter'.... onto the next... Everything in life is a battle to survive - even evolution. I don't think there even being a great filter means that we necessarily wouldn't pass through it... -- I guarantee you there's a great filter...if we never become space faring this world will die -- the sun will supernova. If humans survive to that day, and never leave the solar system then all life here will be snuffed out... If we do survive eons past the end of this solar system at some point the entire universe could contract, entropy could run out and all life would be snuffed out... On a long enough time line -- everything in this universe will be filtered out.