Organisms have to feed. Energy to live must come from somewhere. That would be other organisms, unless you're a plant.
Perhaps there is a race of intelligent beings, somewhere, that feed directly off of sunlight. They're peaceful, benign, and have to reproduce, unless they're immortals, if the race is to continue to exist. If immortal, maybe they're angels; and they probably didn't evolve to that state.
What happens when space and access to sunlight run out? Will they peacefully die so that others may live? Why are not the others doing the same first?
No. There may be non-aggressive races out there, but that will be a philosophical position that they have arrived at when they have fulfilled all their needs (sounds like heaven,, doesn't it?).
If they don't need living space, why are they exploring the galaxy and arriving at our little green speck?
“We’re extrapolating from all the knowledge that we have.”
That’s for sure, but it is still only one example. I think it might be a mistake to determine something must be a certain way because we simply can’t imagine it being any other way.
“If they don’t need living space, why are they exploring the galaxy and arriving at our little green speck?”
Maybe that’s why nobody seems to have visited while we have been paying attention. Maybe sessile intelligent culture is much, much more common than what we are.
Freegards