SIA/anthropics strike again? "Fantastically Wrong: The Scientist Who Thought 22 Trillion Aliens Live in Our Solar System":

Here’s what [Thomas] Dick figured. At the time, there were an average of 280 people per square mile in England. And because he thought every surface of our universe bears life, it would naturally occur at roughly the same population density. So from comets and asteroids to the rings of Saturn, if you knew how big something was, you could guess how many beings live there. Thus, Jupiter would be the most populated object in the solar system, with 7 trillion beings. The least populated would be Vesta, the second largest asteroid in the asteroid belt, tallying just 64 million.

Dick, you see, was a very religious man, but also a voracious scientist, one of the last of the so-called natural theologists, who looked for signs of God’s influence in nature. For Dick, it simply did not make sense for God to have created the cosmos just to have it sit around unoccupied. There must be creatures out there capable of enjoying its beauty, because God wants all his work appreciated. In his book Celestial Scenery...

...You might think that living on other worlds might be difficult, but Dick assures us they’re arranged much like Earth, with mountains and valleys and such. The moon in particular has “an immense variety of elevations and depressions,” and while we can’t directly observe such features on Jupiter, Saturn, or Uranus, given their distance, when light hits them it reveals “the spots and differences of shade and color which are sometimes distinguishable on their disks,” thus betraying the uneven surfaces underneath. (We know today, of course, that these are all in fact gas giants.) God also provides atmospheres on other planetary bodies, “but we have no reason to conclude that they are exactly similar to ours.” Mars’ atmosphere, for example, is denser than our own, bestowing the planet that lovely red hue (it’s actually less dense). Others may be so thin that they allow their inhabitants to “penetrate much farther into space than we can do,” with the added bonus that such an atmosphere could “raise their spirits to the highest pitch of ecstasy, similar to some of the effects produced on our frame by inhaling that gaseous fluid called the nitrous oxyde.”...There is, though, the rather glaring problem of the crushing gravity of a planet the size of Saturn. But Dick posits that “the density of Jupiter is little more than that of water, and that of Saturn about the density of cork.” Jupiter, therefore, would have a gravity only twice as great as Earth’s—not so terrible in the grand scheme of things... And he wasn’t even the first scientist to argue that life existed elsewhere in our solar system. Far from it: It was none other than the famed astronomer William Herschel who argued that not only was there life on every planet, but on the sun as well. That blinding glow we see is simply a luminous atmosphere hiding a rocky surface that teemed with life.

(The Presumptuous Natural Philosopher notes: 'while it is true that we have no direct evidence of life on other planets, or indeed solid confirmation that the other bodies of the solar system are rocky and support life, all of this is at least consistent with our current knowledge, and consider the anthropic aspect: with a global population of ~1b in 1837, and a possible system-wide population of 22 trillion or 22,000 times the global population, would not the SIA provide crushing evidence that the other planets are likely inhabited?')