Just a brief thought, not a full comment, but it struck me today, while reading about Fred Hoyle, that very clever people can sometimes miss obvious problems. Now, I don't have an issue, for example, with his belief in the steady state model of the universe. Granted, evidence goes against it at present, but to be honest, the big bang has some issues as well, such as "Where did it come from? How can everything explode out of nothingness? And what did it explode into?" Basically, any explanation of the universe that is not endless ends up with the problem of creation ex nihilo. Hawking comes closest with his theory of an oscillating universe, since it is essentially a steady state, just with varying size, the universe is eternal, just changing size and shape. Nor do I have an issue with Hoyle's belief in, say, abiogenetic petroleum. I still don't buy the theory, but it is plausible, though, again, evidence does seem to favor the alternative theory.
In fact, I don't even have a problem with the theory I am about to slag on pretty hard. The theory itself is not a problem, I can even accept the possibility. It is the justification that troubles me.
You see, among many other unpopular theories Hoyle promoted is the idea that, to some degree, life on Earth had its origin in space. The degree to which life is extraterrestrial varies between proponents, with some simply arguing the earliest genetic material or even pre-genetic viral material, came from space, with others -- including Hoyle -- arguing genetic material continued to be altered by space-borne viruses and other matter. (Hoyle went so far as to blame several pandemics upon space matter.) As far as it goes, the theory is unobjectionable. It seem, to my amateur's eye, less than convincing, given the relatively strong evidence for genetic continuity on Earth, at least in terms of space having a continual influence, but as to the initial origins, well, evidence is pretty good for a terrestrial origin, but nothing makes the alternative theory impossible.
So, what is my problem? Well, my objection is the justification, that being the part of Hoyle that several ID proponents have also latched onto. You see, Hoyle's argument is basically the same as the irreducible complexity argument of the ID proponents, that life is too complicated to have originated form the "primordial soup". Which sounds fine and good, until you ask, but, if life came from space, how did it get there? Even assuming life is too complex to evolve on Earth, how did it evolve wherever it did originate? And, since Hoyle is not a theist, this is a valid question. Even if we assume intelligent intervention "seeding" life on Earth, we still must ask, how did that life evolve?
And that is why I opened with the statement that I did, that sometimes very clever people miss obvious problems. Now, not having read all of Hoyle's work, being in fact, fairly new to his writing, I am not sure if he did come up with some solution or not, but it still seems to me that this idea of "irreducible complexity" is a bad position unless one is, as with ID, going to promote an extra-material creator, since, if something is too complex to evolve, then it must either not exist, or have some external origin. And, if we are talking about life itself, then we pretty much remove all external origins, making irreducible complexity a problem for those promoting panspermia along with a purely material world view.
As I said, just my initial thoughts, I need to find more of Hoyle's writing on this to see what clever dodge he comes up with to work around the problem of panspermia just pushing the complexity problem off to another planet. When I have more, I will likely comment again.
By the way, to be clear, I am not pushing an ID position here. I have, in fact, been kind of critical of ID, as I believe a creator possessed of omniscience and omnipotence would leave no finger prints, since, knowing all outcomes, he could simply pick the right starting conditions to achieve his goals. God is not some tinkerer who would need to come in and adjust things like a weekend hobbyist working on his model train layout. Being omniscient he would get it right at the first try. So to say God would leave visible signs is, in essence, to postulate something not like an omniscient God, but more like the Greek and Roman deities, who make mistakes, get in each others' way, and essentially are less Gods and more superhumans. ("Some Thoughts on Arguments for Intelligent Design", "Materialist Arrogance")
To be clear, I am not arguing against panspermia's complexity problem to push a creator, but rather to argue that creation on Earth still seems most likely. Evidence is good for the primal conditions producing lots of early precursors of life (amino acids, other long chain molecules, proto-cells, etc.), so it seems to me, given a very long time and a lot of matter, life originating on Earth is not too implausible. (Whether or not a creator is involved is a question of faith, not science, or so it seems to me. Unless, somehow we could find evidence of a the sudden, miraculous introduction of life without source. But even had such been the case, the idea of finding convincing evidence is pretty implausible.) So, unlike those promoting ID, I am not pointing out problems in Hoyle's arguments to push God, but rather to suggest maybe the theory is flawed.