Dwarf planet Ceres boasts organic compounds, raising prospect of life

My point is precisely that this isn't just random chauvinism, which is rather than being some sort of way-cool open-minded "whoa" opinion is really rather insulting to the huge number of scientists who have considered this matter very carefully. There are a looooooooot of good reasons to think carbon is the only possible substrate for life in this universe, and a lot (still italicized, but with fewer "o"s) of good reasons to think water is the most likely choice.

For example, CH4 (methane) is a nice stable molecule. It exists underground for millennia. SiH4 (silane) is an unstable, pyrophoric (spontaneously ignites in air). There is no evidence to suggest that a silicon-based life form could exist.

Yea. The argument is actually independent of whether the probability of abiogenesis is large enough for life to independently arise multiple times in the solar system or (conversely) small enough that it's very unlikely for it to exist elsewhere in the observable universe. I think all it requires is that abiogenesis is a combination of several small probabilities distributed over several orders of magnitude. (If the probability is large enough that multiple forms routinely develop on the same planet, then we probably also have to assume something about, say, the first-mover dominating.)

> But how does one estimate probabilities of abiogenesis, or their relative magnitudes?

It's really hard.

> Are there e.g. scientific papers published on this subject?

Yes, but I don't know them off the top of my head, or whether any are any good.

You probably covered some of this in school, though it tends to be an aside in your chemistry or biology book and easy to miss. But people have done the basic experiments with taking a bunch of likely looking chemicals, based on what we think the old Earth looked like, and shooting electricity through them and other such things that seem like they may have contributed to life.

Those experiments came up negative; life isn't that easy. That has been so thoroughly absorbed into modern consciousness that it can be easy to forget that they were perfectly legitimate experiments to conduct, and had they come out positive, that pretty much would have ended all debated about how common life is in the universe, moving the discussion firmly into the "intelligent" part of the issue.

You can also try to create "minimal organisms" that are sufficiently simple that they perhaps could be randomly created.

However, last I knew, computing odds of abiogenesis is still effectively impossible because there are still some steps that we simply do not know how to get past via random processes, such as ensuring the chirality of the molecules matches. That's not to say there's a lot of ideas out there on how to get over various elements of the problem, but at the moment I think it's fair to say that the best science we current have puts the odds of abiogenesis at simply "impossibly unlikely". Stay tuned for more "best science", of course.

Does it not seem statistically improbable that in the entire universe, life only occurred once?

Personally I think if I believed that, I'd have to accept a creator deity of some kind as well.