Absent data the reasonable hypothesis is that circumstances here on Gaia Earth are close to the mean. The least reasonable, raving lunatic idea is that Earth is W-A-Y out there 5+ standard deviations away from the mean
special. Thats irrational, not defensible, is just for popular mass consumption by bovine idiots and jehova witnesses. Science knows the law of large numbers (billions or maybe trillions of planets) means the only rational concept is that any phenomenon in our experience is distributed across the numbers.
We have to speculate because we dont have data to estimate what mathematics the distribution follows, how life may be distributed among the vast-beyond-imagining numbers of worlds, in this dimension of reality, which is perhaps merely one nit among a vast population of alternative realities in a vast cosmos. String theory and Brane cosmology and people like Lisa Randall etc. speculate about cosmologies like that.
Within this cosmos (just our dimension), were forced to guess because we have no data (but the US Government probably does). The most rational guess is that life follows some distribution, is scattered across the many worlds according to some distribution describable by math. Since were forced to guess because we the civilians have no data, the best we can do, the most rational GUESS, is that life follows the normal distribution (z curve) across the planets and dimensions.
Its irrational, indefensible, nearly to the point of a mental illness, to claim Im from Missouri and deny all until you show me, we are alone, special creation! Your Science education has already showed you, by demonstrating that pretty much everything follows a distribution. Intelligent life too!. Especially contemplating billions or trillions of planets in this dimension alone, maybe one miniscule nit in a tremendous cloud comprised of trillions upon trillions of alternative dimensions.
And remember, our dimension is more than the physical cosmos. It's also all the sights, sounds, emotions, thoughts, experiences, etc....that's ALL merely ONE dimension in the vast universe.