I thought Maastricht is a psychologist who worked for a stretch in plant spotting and identification. A very strong special interest in botany, but unknown whether any actual college-level coursework in biology (or other hard sciences?
If our set is “celestial bodies”, then yeah, we’re found thousands of those, and only one has life (so far). If you’re talking about “planets”, we’re dealing with a much smaller subset, even if you include moons and dwarf planets in your count. And frankly, we don’t know that simple life doesn’t exist elsewhere in the solar system yet, or that it didn’t exist at some point in the past. Certainly nothing very large or complex, and certainly no intelligence, but single called life under the ice of a frozen moon, underground on a “dead” planet like Mars, or in the depths of a gas giant is not impossible.
But if our set is “rocky planets with surface water that’s mostly liquid” then we do have a set of 1. We know there are other rocky planets with surface water out there - and have no reason to believe that bit is vanishing rare - but we have no info at all about how many of them have life.
It’s also true that we know the galaxy isn’t crawling with advanced civilizations, but that’s the whole point - does that mean that any life at all is rare? That multicellular life is rare? That intelligent life is rare? That civilization is rare? That interstellar travel is rare? We don’t know.
I’m confining my stance to “life”, not “intelligent life”. I agree we don’t know, but like I said, given our current theories of abiogenesis, and the abundance of precursor molecules out there, we can say whether it is probable or not.
Maastricht - upon your return could you clarify the “larger truth”?