The existence of life in the face if its miniscule probability of arising by chance is sometimes offered as something with significant import and requiring a satisfying explainaition, whether the explanation is God, or some unknown aspect of the physical universe, etc.
I toss deck of cards into the air. Some land face up, some land face down. Supposing each card has a 50-50 chance of landing face up. Therefore, after I’ve thrown the cards, I point to them on the ground and say,
“Isn’t it amazing. There is only a 1 in 2^52 ~ 10^36 (1 followed by 36 zeros) chance that throwing the cards would result in this arrangement. And yet there it is.”
Why is the existence of life, though improbable, any more suprising or in need of explaning than the particular arrangement of cards? Both are improbable but both happened. Improbable things happen all the time.
This is not a rhetorical question btw. I suppose I am missing a step in the logic with regard to the life question and I genuinely want to know what it is.
For a simple answer, I think because, without life, there wouldn’t be anyone to wonder about the probabilities. It’s sort of how, for instance, you see a spectacular play in sports that requires a lot of skill and luck to pull off; you’re just not going to wonder about how rare that is except for the fact that you just saw it.
The other part, perhaps more to what you’re looking for, depends on your view of the cosmos. If we’re part of a multiverse, where every possibility exists in one of countless universes, then it isn’t interesting at all, as only those universes that are capable of sustaining life will. If, however, there is only one (or, perhaps, small finite number of universes), it does become an interesting question. Why, out of a countless number of possibilities, did this particular possibility get chosen? Sure, we can assume it’s utterly random, but it may not be, there may be reasons why particular constant values are the way they are or why seemingly random events came out the way they did and our science just isn’t advanced enough or our assumptions are far enough off base, that we don’t yet know why.
But really, regardless of whether you’re theistic or not, I think it’s natural for the human mind to assign meaning and value to things. It’s the same way that things “always happen in threes” or “everything happens for a reason”. You may not believe those things, but many people do, and even if it is true that there’s no reason, our pattern seeking brains will often find that explanation unsatisfying.
You are missing something crucial here. If you predicted the arrangement in advance, and got it, that would be amazing. After one of the 2^big n possible arrangements shows up, the probability of it is 1, not that this means anything.
Another example. The probability of a baby with your genes coming out of the mixing of your parents’ genes would be miniscule, if predicted in advance. The probability of a baby showing up with some mix of genes is 1.
This, in short, is the Anthropic Principle. Depending on your taste, it can mean we can’t say anything about the likelyhood of a universe being hospitable to life until we find another universe (the apparent “fine tuning”) or how likely it is that other planets have life until we find one that does (see this rather messy thread that’s still continuing).
Aside: it’s not clear to me how (if at all) the Anthropic Principle relates to the number of universes or worlds, since to some thinkers at least, it appears to destroy any way of saying anything at all about the likelyhood of conditions we find ourselves in (as far as those conditions are necessary for intelligent, observant life), while other argue that large numbers of possible “habitats” are necessary for the AP to be a valid construct.
I don’t think we really need to bring in hypothetical other universes. The example of the cards does not depend on any additional instances of tossing the cards. We only need one.
I agree. However, my question wasn’t referring to future life or particular lifeforms. I was referring the arising of life X billion years ago and its evolution until today, and set of events that have already occurred. Yes, the probability of any previous event is 1. Which is why I don’t think any a priori estimation of probabilities is logically significant.
The point I think, is, that if there really are infinite numbers of alternative universes, there will be ones that have intelligent life (and of course, we’d be in such a universe) - in other words, (intelligent) life would be nothing remarkable in that universe (probably).
At the moment we know of no extra-terrestrial life, but we do know that we are alive. If we take the multiverse hypothesis as true, and also assume there’s a range of possible universes, we can discard (because of the Anthropic Principle) all the universes that don’t support life.
This leaves us with a universe where it’s somewhere between extremely improbable to extremely likely that life can arise under “typical” (say, roughly earth-like) conditions. Depending on the distribution curve, this can easily mean we’re more likely to live in a universe where life is more likely than not - universes where life is extremely improbable might be less common and besides, a universe where life is common has a larger chance of having us in it than one where it’s rare.
In the end though, we just don’t know until we find more life. Personally, I find the argument that life arose very quickly on earth a fairly persuasive argument that life is probably not extremely rare.
Thanks for the links, I didn’t know the official term for that concept; looks like it will be an interesting read. Also, thanks for clarifying on my point.
But really, it all comes down the the fact that we don’t know anything about the probabilities because we have only a single data point. Life could be extremely rare or it could be extremely likely, we just don’t know. Hell, we can’t even say for sure whether there was ever life on mars.
Or to related back to your example with your assumptions, no one is going to think anything special when roughly half are face up. OTOH, if you toss the deck of cards into the air and every single card lands face up, you can bet that it someone looking at it would be impressed, even though it’s just as likely as the previous case, it’s just that one result is “typical” and one is not. The thing is, we’re looking at our universe and, because we exist, we assume it’s a special case, but it may not be.
From my reading and research, it appears to me to be likely that “life”, or at least lifelike patterns, will naturally tend to arise as an emergent property from a system of sufficient complexity, especially if an element of competition is present.
Merely because that is the topic of discussion: If it is improbable, does it matter? I would not defend that it is improbable. This is just suppose it is improbable…
Your card example only makes sense in reference to a particular life form.
Dawkins notes that there are many more ways for things to be dead than alive, and so the life had to happen argument is not very useful. Much more useful is to enumerate several paths to life, estimate the probabilities for each step along those paths, and get an estimate of the probability that life could arise. One is the probability that there are earth-like planets. This seems higher than previously estimated. Then there is the probability that conditions supporting the mixing of organic molecules arise on these planets. We don’t know this, but I don’t see why it would be very low. Then there is the probability that this mixing would result in a self-replicating molecule. That is a fairly big unknown. Finally, there is the probability that this molecule would evolve into something we’d call life. I guess that would be pretty high, given the reproductive advantage more complex living things have.
First of all, 2^52 is not roughly equal to 10^36. It is roughly equal to 10^16.
Now, in answer to your actual question, the answer hinges on how you define “in need of explanation”, but most folks can state pretty clearly what outcomes are clearly indicative of somebody meddling with the results. Consider flipping a fair coin thirty times. The following two outcomes are equally likely.
HHHTTHHTTTTHTHHHHTTHTTHTHHTTTH
TTTTTTTTTTTTTTTTTTTTTTTTTTTTTT
However, if I observed the first one, I wouldn’t see any need for an explanation. If I observed the second, I would. For similar reasons, life in the universe, to most, demands an explanation.
If, after the observations you note in the second case, you predict that the next 10 results will be T, and it happens, then you need an explanation. Or, if before beginning, you had a hypothesis that the coin was loaded to T, then you have supported your hypothesis with a good p value and can next look for a reason. On the other hand, if your hobby is tossing coins, and you wind up with a lot of Ts one day, there might be nothing to explain.
Remember statistics do not tell you what WILL happen, only what is LIKELY to happen.
I could throw a coin in the air a thousand times. Statistics say it’s LIKELY to come up heads 500 times and tails 500. But there is nothing to say it couldn’t come up tails all 1,000 times.
It’s not likely but it is within the realm of possibilities