Is it possible to have liquid water without life? I remember reading that an oxygen atmosphere was quite impossible, but am not sure about liquid water.
There could be an oxygen atmosphere without life for a short period of a planet's history (I'm not sure how long.) It wouldn't be possible for it to remain permanently.
According to our evidence, Mars had liquid water for a very long period, but no one considers this to be proof that there was life there.
I would like to propose this as a thread for people to write in their predictions for the next year and the next decade, when practical with probabilities attached. I'll probably make some in the comments.