Arbitrary Aliens

A couple of people asked for more details on the conversation I had with friends the other night about whether it is possible that there is extraterrestrial life, or whether that claim is arbitrary.  It's hard to write anything coherent to summarize a conversation that had no real conclusion (especially since I am the one with the most confusion on the issue).  I can, however, present what I recall in an unstructured way, which is how a conversation goes.  I hope it is intelligible.

We all agreed that ET life would be arbitrary if there was no evidence for it - if it is just pure speculation.  But the real sticking point is the question of what constitutes evidence.  Does one instance of something imply that there might be other instances (life on earth=POSSIBILITY of life elsewhere)?  No, I think we all agreed. 

We went through some history about how humans did not even have evidence for planets outside of our solar system until about 10 years ago.  We knew we had planets in our solar system, we knew there were other stars, but there was no direct evidence for extra-solar planets at all until very recently.  How could one consider it possible that there is life elsewhere when you there is not yet evidence of a planet for that life to live on.  Well, I did, but I'm not sure it was justified.

What if we found evidence of life on a body in our own solar system, past or present?  Would that be evidence for possible life outside of our solar system? Or would it only apply to our solar system?  (Actually, I don't think we discussed that the other night, but I've discussed it with Adam before.)

Now that we do know there are other planets, does that move ET life into the realm of the possible?  Adam says no, that you still need to have evidence that there is at least one other earth-like planet.  What we know is that life happened here.  It hasn't happened on any other body in our solar system as far as we know.  The laws of causation tell you that there must be certain conditions required for life, and all we have to go on is what happened here.  But we don't even understand the "how" here.  Still, if we found another planet that had x,y, and z conditions (which we are not qualified to name) then we would at least know that there was a second place where conditions made life possible.  (Earth could be unique, after all.)  But another thing we realized is that we're not even sure scientists today could fill in the x,y, and z above.  Humans might not even know what would constitute evidence in this case, let alone have that evidence.

But now that we know there are extra-solar planets, we thought that it is now within the realm of the possible that there is another earth-like planet.  And I'm still not sure why we can't go one step further and say that if that is possible, then so is ET life.  But both K. and Adam agreed that you can't skip a step - that possibilities are not evidence.  That does make sense to me, but I still fight it.  Something is still missing for me here.

I think a big part of my problem is that I buy the argument of numbers and time.  It rings true to me that the amount of planets (although we really do not have a good idea of how many there are yet) and the amount of time in the universe allow for so many possibilities, that the idea that earth is unique seems far-fetched.  However, K. brought up that if you play with the actual formulas for the possibilities, it is easy to make it come out that there are more variables required than planets in the whole universe, and earth might indeed be unique.  We just don't have enough facts to use the formulas at all.  I might have to look more closely at that issue because it is still compelling to me and I'm not sure why.

Still, is that last argument just a statistical argument?  And are statistics evidence?  I don't know the answer to the first question, and I'm not clear on the second.

I also brought up the problem of induction and that I have a sense that, if you dispense with the arbitrary as defined this way, you'd never have any reason to explore or use your imagination or come up with a new hypothesis.  I do know that a hypothesis requires evidence, but what comes before the hypothesis?  If it is arbitrary to speculate about something with no evidence, then what drives us to explore?  Sometimes you come across evidence you weren't looking for, but sometimes you need to be looking.

So what other type of evidence would bring ET life into the realm of the possible?  We didn't get any further on that, but we did use a great analogy of a civilization on an island that has never seen any land mass except their island.  Would it be arbitrary for them to speculate that there might be land other than their own, let alone other humans or even life?  We agreed yes, which supports Adam and K.'s position.  But we asked what would be the evidence to make it possible.  We thought of them observing land under the ocean and how it rises and falls, and that they could conclude that it might rise above the surface in areas other than their own.  That would be evidence.  Also, if they saw birds not from their island, that would be evidence.  (Adam said he thought that the bird example really happened in history.  If anybody knows about that, please comment.)  We also thought that, without more evidence for these islanders, it would be as reasonable (which is not at all) for them to speculate about another land mass in the sky as somewhere else in the water.  That analogy was helpful in realizing how your own context can lead you astray.

Then finally, this brought up the question about why it is so compelling to think of the possibility of life on other worlds.  K. speculated that there is just so much fiction about aliens that it "feels natural."  Maybe.

I identify at least one mistake in my thinking about the concept arbitrary.  I used the concrete "god" as a stand-in for the concept.  And in the past the concept of god might have been arbitrary speculation, but today, it is false, so now I'm confusing "arbitrary" and "false."  Even if god were arbitrary, you can't hold a concept properly with one concrete as a stand-in.  I definitely need to work on my understanding of arbitrary.