But the Earth is rather unique even within the context of RET. How come you believe reports of all other celestial bodies in the solar system being entirely lifeless, but you somehow think there might be life on Earth?
I've seen this said before, maybe by you, I can't remember.
I completely disagree with this assertion. Earth is, admittedly, the only place we know of where life exists but
a) We have a very small sample set of planets to check, compared to the scale of the universe.
b) Our exploration of them is in its infancy, relatively speaking.
We've sent probes to all the other planets in our solar system now but only landed on 2 of them. We've never sent humans to any of them. We can be pretty confident there's no
intelligent life anywhere else in the solar system (the word "else" is possibly superfluous
) but could there be microbial life on one of the planets or moons? There are a few potential candidates and we've only just started scratching the surface in terms of exploration. It's only in the last 50 years we've had the technology to start exploring them and because of the distances and complexities involved we are very much at the start of that exploration.
Could there be life or even intelligent life elsewhere? We now have the technology to detect exoplanets but that is even newer than our ability to explore the planets in our own solar system. We are starting to discover planets in the so-called Goldilocks zone, we're able to pick up signatures from the atmospheres of other planets which hint at liquid water on some of them. From what we know about life on earth water is a prerequisite but, again, we only have a very small sample of planets to study the conditions which make life possible. It's a big universe. So big that some people believe that intelligent life is inevitable elsewhere. The fact is, we honestly don't know.
Our mentality that our planet is special or unique or has some privileged position in the universe is based on the fact that for most of our history we didn't have the technology to know different. It wasn't until the middle ages we realised that we weren't at the centre of the universe. It's only the last 50 years we've been able to start exploring the other planets and only in the last 30 we've started to be able to detect exoplanets (I'm surprised it's that long, according to Google the first one was discovered in 1988, it's certainly only recently we've started discover them in volume and be able to infer details of their atmospheres from spectroscopy).
In lots of ways there is nothing special about the earth. From our explorations of the other plants so far it looks like many of the same features found on earth are present on the other planets. They have volcanos and seismic activity, mountains and valleys. We think there are oceans on some of the moons. Mars has ice water and some of the features are highly suggestive on liquid water flowing at some point in the past. Did life ever exist there? Does it exist in any form now? We're so new to the exploration of it, relatively speaking, it's impossible to be sure.
The assertion that the earth is unique comes from religious belief or the limits of our scientific knowledge. Currently there is no reason to think there is anything special about the earth. It's possible we are the only planet in the universe with intelligent life on but the more we understand about other planets in our solar system and the similarities we see, the more we understand the scale of the universe and the prevalence of planets orbiting other stars the more plausible it seems that there's nothing special about our place in the universe and nothing unique about the earth at all.