"fine tune the solar system once in a while to keep it working."
This is the finest argument for why we need vastly more science and statistics on extrasolar planetary systems, their accretion models, particularly the frequency of comet shielding jupiters at jupiter distances, and if at all possible, the frequency of terrestrial magnetic fields, and the frequency of terrestrial moons. The closest thing in our solar system to fine tuning is jupiter and what it does with asteroids and comets, and the moon and what it does, and the odds that it formed how it did, and what it did and continues to do for the earth. But raw numbers and computer modelling, and things called gravitational focusing, and impact parameters, and Lagrange points, and Hill spheres, and Roche lobes, and conservation of angular momentum, and virial theorem, along with hydrostatic equilibrium, can address these marvels.
Edit add: The carbon/oxygen ratio is a recent hot item in planetary science that offers questions on the prevalence of water. If there's "too much" available carbon, it grabs the oxygen and there is much less oxygen to form water. But if there is "just" the right ratio of carbon to oxygen, there's plenty of oxygen left to form water. There are a surprising number of stellar effects that can alter where the ordinarily average complement of carbon gets placed early on. So more research, more modelling, more observations, more white papers are required. Unless that happens, all we really have is a god, a firmament, two waters, an old book, an aetiology, and some people that rely on what their parents and culture told them, and their intuition, when more quantitatively and qualitatively powerful tools of analysis exist. Their choice.
