Well, we seem to be off to a good start. I do have work tomorrow, so I'll just get this in now and let everyone stew over it all day. The best sauce and all that...
Since we already kind of got started in this direction, I'll put in questions 2 and 3 from The Emergence of Life - Chapter 1. This link is to my review of chapter 1. Here's a link to the book on Amazon (I get no income from this). But at the least you'll understand the thinking behind determinism and contingency. [NOTE: You'll find I link to Wikipedia a lot. It's a convenient location for much of the material that I think you might benefit from. I do not consider it an authoritative source, but the references and further reading are often peer-reviewed works that will describe material in detail, with authority.]
Chapter 1 - Question 2:
Do you accept the idea that biological evolution is mostly shaped by contingency? If not, what would you add to this picture?
First we need to talk about contingency and determinism. In the book, Luisi describes determinism (in this context) as the notion that life can develop purely by the interaction of chemical and physical processes. In other words, if the chemicals are available, life will develop. The opposite of this thought is NOT that there was an intelligent designer or something like that.
The other position is that of contingency. That is, the interaction of many factors (the majority of which may be deterministic) is required in an unlikely sequence of events to result in life. Contingency is something like chance, but not quite. Luisi describes it as this way. Contingency is getting hit on the head with a piece of tile roof. The deterministic factors (your walk to work, the poor condition of the roof, wind, gravity, etc) all combined to result in you getting hit with a piece of tile. Another way to look at it is what I call the “re-do” effect. If you reset everything back to the way it was before you walked to work, would you still get hit with the tile? If we reset the universe back 6 billion years and let it run again, would be in exactly the same place we are now?
In my mind contingency is the philosophical equivalent of chaos theory.
Now to answer the actual question. Is biological evolution mostly shaped by contingency?
First, this is a rather curious statement considering the focus of the book. Evolution really doesn’t have that much to do with abiogenesis… or does it. It can be shown that evolution occurs with any system that replicates imperfectly. Is a single RNA strand alive? If not, then we do have evolution on non-life and that evolution may drive replicators toward life. However, is evolution contingent anyway? I think so, if only because of the massive amount of potential influences on an organism. Mutations, environmental effects, what actually determines relative fitness, etc are all contingent things. A particular mutation might be great in an ice age, but if it's not an ice age, then it may be useless.
As far as abiogenesis is concerned, before reading this, I was squarely in the deterministic camp. However, contingency makes a lot of sense. It would explain why we haven’t heard from aliens (of course, there are lots of other reasons for that too).
At this point, I’m thinking that life is probably pretty common in the universe. However, I’m wondering how much life exists beyond slime molds (or alien equivalents)? Is multi-cellularity much more difficult to achieve than we might think? With a sample size of 1, it’s difficult to really examine this, but research seems to indicate that being multi-celled is useful and so may be likely once cellular organisms exist.
Intelligence may be less likely than multi-cellular organisms, but again, a small sample size has resulted in little ability to explore.
I can see the value in both positions. I think the future research that will be done in space exploration may well give us evidence one way or another. If the deterministic proposal is correct, then we should see a universe filled with life in all kinds of strange environments (more on this later). If contingency is more correct, then we should rarely see life and even more rarely see intelligent life. Which neatly segues into the third question...
Chapter 1 - Question 3:
Are you at peace with the idea that mankind might not have existed; and with the idea that we may be alone in the universe?
65 million years ago, dinosaurs were satisfied. They had existed on this planet for over 160 million years (almost a 1000 times longer than modern humans have existed). Mammals existed for much of that time, but they were rarely much larger than mice.
It took a freak accident to allow the rise of mammals, which has resulted in the development of modern humans. Without an asteroid crashing into and utterly devastating the planet, we would not be here. I have no problem with that.
I’m not so sure about ‘alone’. In the sense that humans may be unique as the only sentient species (i.e. capable of ad hominem arguments and recognizing the fact), I can live with it. I’ve read too much science fiction to be comfortable with the idea… I want to believe. But I can live with the idea that we are unique. That doesn't imply special privilege or a designer or anthropocentrism in my book. It just means we are lucky.
But in the sense that there are other living things, I don’t think I can be OK with that. I believe that there is too much energy in the universe (in the physics sense) and the likelihood of complex chemical reactions is too great to say with any confidence that Earth is the only planet with life. Since we find organic compounds in the most unlikely of places (nebula and comets) I think that life is not only possible, but likely to exist elsewhere in the universe, perhaps even elsewhere in the solar system. This life, like the dinosaurs may be satisfied at whatever level it has obtained to this point, but I doubt it. Life changes. Darwin and hundreds of years of observation have shown us that life changes and in ways we cannot imagine (reptiles developing a proto-uterus for example).
Again, this is my belief, but if life exists elsewhere in the universe, then intelligence also exists in the universe.