Because we have no evidence to suggest we are anything but, and we don't know if there will be others.
Given that we believe the universe to be infinite, we could be 1st, 2nd, 3rd, 3 billionth, etc. But one thing is for sure, we're on the list, but our likelihood of correctly guessing our position on the list is 1/Infinity.
However, if we assume that there is SOME constraint, then that list is no longer infinite. Instead of our 'guess accuracy' being effectively 0, it's 1/<list length>.
If there are 3 billion, we might be 3 billionth, but if there are 2 billion, we are definitely not 3 billionth. The same follows all the way down to if there are only two, we may be either first or second. We know that there is at LEAST one, so if we guess first, we're at least certainly not guessing out of range.
The probability, without any other information to the contrary, of us being 'first' is higher than the probability of us being 'second' or any other possible point on the list.
Therefore it is a more logical conclusion—although clearly it should not be parroted as a fact.
> Because we have no evidence to suggest we are anything but
I'd say we do:
- we have plenty of evidence that at a given point of time, our knowledge/evidence is incomplete (consider the history of science) - so, since we are at a given point in time, it seems reasonable to consider the possibility that we may still be in a position of non-omniscience.
- we have plenty of evidence that how things appear to people (say: no evidence) is very often other than how it really is
> The probability, without any other information to the contrary, of us being 'first' is higher than the probability of us being 'second' or any other possible point on the list.
This seems very unintuitive to me, is it possible to demonstrate this in some sort of a mathematical form (And: is the only possible probabilistic calculation one could do)?
> it seems reasonable to consider the possibility that we may still be in a position of non-omniscience.
Not even reasonable, in fact, this is one of the premises of my statement.
If we knew for sure how many intelligent species have spread intergalactically, we would not need to be making estimates.
For the clarification of doubt, where I say 'no evidence', I am referring purely to the absence of evidence, not evidence of absence.
I am not sure about representing it formally mathematically, and I am certain that it is not the only probabilistic calculation possible, there may well be better models, but consider the following:
I reach into a bag, and I pull out a die. The die has a one on it.
We have the following assumptions:
- The bag contains at least 1 die
- Dice can have 1 or more sides (let's call them 4D dice)
- All dice have at least one face with a 1 on it
Here, the faces represent the number of intelligent species spreading intergalactically.
The specific number drawn represents humanity's place in the sequence.
Let's initially start with 1, single sided die.
- What is my probability of drawing a 1 sided die? 1 out of 1.
- What is my probability of being position number 1 on the die? 1 out of 1.
So, if there is only 1 die with only 1 face in the bag, we know for certain we must draw a 1.
Now let's imagine adding dice. We add one more.
- What is my probability of drawing a 1 sided die? 1/2
- What is my overall probability of drawing a 1? There are two 'ones' and one 'two', so 2/3
Let's add another.
- What is my probability of drawing a 1 sided die? 1/3
- What is my overall probability of drawing a 1? There are three 'ones', two twos, and one three, so 3/6
This is enough to start to see the pattern, we can see that regardless of the number of dice we add, there will always be more 1s than any other number.
We can throw 10 000 dice into the bag. There will be 10 000 opportunities to be 'first', 9 999 opportunities to be 'second' and so on.
Because we don't know how many dice are in the bag, 'one' is a better guess than 'ten thousand'.
[0]: It's worth noting we're not travelling intergalactically (or even interstellarly) just yet.
> For the clarification of doubt, where I say 'no evidence', I am referring purely to the absence of evidence, not evidence of absence.
Technically, you are referring to your model:
a) it is possible that evidence can exist but a human does not have knowledge of it
b) it is possible that people have differences of opinions on what constitutes evidence, because that is largely a subjective matter, and humans are famous for being unable to reliably distinguish between objective and subjective matters
> I am not sure about representing it formally mathematically, and I am certain that it is not the only probabilistic calculation possible, there may well be better models, but consider the following...
I think my (highly unusual) point of contention here is other than you intuit - your earlier comment ([emphasis] mine):
>> [The] probability, [without any other information to the contrary], of us being 'first' [is] higher than [the] probability of us being 'second' or any other possible point on the list.
You have made a prediction about reality based on "a" model, but speak (and perhaps believed, at runtime) that it is "the" model.
As for your argument, while it's all true, I cannot see how this can cause reality itself to be a particular way. Statistics and thought experiments (~~propaganda~~ journalism, ideologies and ideology ~marketing, etc) can (and do[1]) certainly cause reality to appear a certain way, but that is something very different.
Your argument is that my model is flawed because it might not be correct?
That's a bit post-hoc. If I observe 10 coin tosses, and all ten come up heads, and based on that I devise a model that coin tosses always come up heads, then my model will be incorrect, the correct model is still 1/2. Unless of course, the universe is deterministic, in which case the correct model will actually be a list. Or in case it turns out that coins land heads due to a fluctuation in the coin-toss field which we are not currently aware of, so the correct model would involve first observing the coin-toss field.
Obviously a model does not cause reality to be any particular way. A model merely tries to describe and predict. Models get refined as new evidence or data is added to them.
Until we come across intelligent life in the universe, our model is incredibly basic, and yet we have nothing better.
> Your argument is that my model is flawed because it might not be correct?
Not quite - I am noting that you speak as if you are not working from a model.
"For the clarification of doubt, where I say 'no evidence', I am referring purely to the absence of evidence, not evidence of absence."
As I noted, you do not actually know if there is no evidence absolutely, you are describing the absence of evidence in your possession/knowledge.
> That's a bit post-hoc. If I observe 10 coin tosses, and all ten come up heads, and based on that I devise a model that coin tosses always come up heads, then my model will be incorrect, the correct model is still 1/2.
Sure, but in this case we are not discussing a well known domain (coins), we are discussing a not known at all domain (aliens).
And even here in your simple thought experiment, there are facts that you do not have knowledge of (a rigged coin, that you do not realize is rigged (according to your description) because "based on that I devise a model that coin tosses always come up heads").
> Unless of course, the universe is deterministic...
Another matter that is not known, but broadly believed to be known.
> Obviously a model does not cause reality to be any particular way.
Generally agree, but even here it's not that simple. Models can cause reality to appear a certain way (consistent with the model), and perceptions of reality are a very important component of reality (very often more important than "actual" reality, in that belief > truth when it comes to human action, which is what determines the end state of physical reality).
> A model merely tries to describe and predict. Models get refined as new evidence or data is added to them.
Disagree. Some models are built to deceive - see: propaganda/journalism/etc.
> Until we come across intelligent life in the universe, our model is incredibly basic, and yet we have nothing better.
Better models are possible: for example, it is possible to make epistemic status(es) a first class concept. Early 21st century humans tend to very much not like epistemology and logic, but it is there for our usage if we should ever change our ways.
I think that depends on the size of the universe. If the universe really is infinite, I don’t think we can say anything about where we are on the list. Even if only one star in a billion galaxies has intelligent life, there could already be an infinite number of civilizations ahead of us.
> The probability, without any other information to the contrary, of us being 'first' is higher than the probability of us being 'second' or any other possible point on the list.
That doesn’t make sense to me. It seems like, assuming we’re not the only ones and we’re randomly likely to appear in the list, we’re far more likely to appear in any other position than the first.
There’s also a separate interesting thing where “first” is kind of non sensical when you’re talking about the universe. There’s no global ordering of events.
It’s true, we’re more likely to appear in a position other than one (not “any other position” specifically though), but your assumption that we are not the only ones is doing a lot of heavy lifting here.
The existence of life in the universe is clearly a non-0 probability event. Same for “intelligent” life. Although arguably almost all life on earth is intelligent so I’m assuming you mean human-level intelligence. Well, in which case we probably have a few contenders for at least getting fairly close if not matching given we have trouble defining intelligence (elephants, octopus, dolphin, some primates, crows etc). Let’s say life that can build technology and shape the world around them then.
If the universe is mathematically infinite, then it’s guaranteed we’re not the only ones because any low probability event will still happen infinitely many times in that case. So let’s say the universe is very very large but not mathematically infinite.
So then the question is a) what percentage of planets develop life b) what percentage of life develops a species capable of building technology c) what is the likelihood that species has access to resources on the planet to build that technology. We don’t know what a) is (just non-0) but using your equivalent argument for that of “we haven’t found any” I can counter by saying well, as far as we know b and c are 100% as the only planet we know to have life developed a intelligent technology-building species and the likelihood that that just happened by luck seems astronomically low (ie you’d need life to be extremely common and intelligent life not so but the odds seem against you if life is rare AND intelligent life is rarer still). I would argue that when life develops intelligent life is almost assured because pf evolutionary pressures. Now whether the right circumstances exist for them to evolve from basic tools to space ships, who knows. But that’s secondary.
So does life exist? Given the size of the universe it would be hard to bet against the argument that life has evolved somewhere out there in the universe. And given that it has, what are the odds that intelligent life came about? Again I’d say high because the same evolutionary pressures would exist to fill in niches that intelligence wins at.
So I don’t think it’s all that heavy a lift. Note that I’m not claiming they are space faring, have developed advanced mathematics, can communicate in any way that we’d understand each other or anything like that. I’m simply noting there’s multiple species even here on Earth who at a minimum come close to humans, which means the probability seems quite good unless our Earth is a magical place in the universe that is particularly special somehow at generating sentience. Thus the odds of there being intelligent sentient life out there seems to be the same as whether or not there’s any life out there. And since we know that’s non-0 and the universe is very very big, then it stands to reason there’s very likely intelligent life out there. Note even the observable universe itself is big enough that there’s likely other intelligent life within it. The total universe is much much larger than that and we’d never ever see evidence of life from there because we’ll never see anything from it because it’s forever outside of the expansion of the universe.
> If the universe is mathematically infinite, then it’s guaranteed we’re not the only ones because any low probability event will still happen infinitely many times in that case.
This isn't really true in any meaningful sense.
What is the probability of me tossing a coin immediately after writing this comment, and it landing heads? As I write now, it is 1/2. However, it's clear that only one outcome is possible. EDIT: it was tails. It didn't come up heads, however infinite the universe may be, it just didn't.
(Note: there is a non-zero probability that a similar being sits in front of his computer in a similar shirt, having a similar online discussion, who tosses a similar circular disk which comes up a different way, but that being is not me).
> the likelihood that that just happened by luck seems astronomically low
It seems that way, but as you are arguing elsewhere, unlikely things can and do happen in the universe.
> Note that I’m not claiming they are space faring
That's part of OPs premise, but I don't mind leaving it out of the discussion.
I actually like your formulation:
a. what percentage of planets develop life
b. what percentage of life develops a species capable of building technology
c. what is the likelihood that species has access to resources on the planet to build that technology
I'd argue with the 100% for b and c, because we have at least a reasonable belief based on observation that there is no other intelligent life in our solar system, and we have evidence that planets exist without those resources to build technology, but it's not the crux of my argument.
The crux of my argument is really a). We don't know what percentage of planets develop life. But as yet, we are unique.
On a personal level, by the way, I do actually suspect that we are not alone in the universe, but that's a gut feeling, and I don't believe there's maths to support it.
Side note while I think about it, actually we have more evidence than we think. Even on a planet clearly adapted to support life in massive varieties, it seems that all life on earth evolved originally from a single organism. We have millions of years of geological and paleontological evidence, and thousands of years of recorded history, and we have no evidence that this happened more than once.
It does certainly seem from our limited evidence that abiogenesis (or going from not alive to alive) is at best extremely uncommon, or at worst, an isolated anomaly.
Given that we believe the universe to be infinite, we could be 1st, 2nd, 3rd, 3 billionth, etc. But one thing is for sure, we're on the list, but our likelihood of correctly guessing our position on the list is 1/Infinity.
However, if we assume that there is SOME constraint, then that list is no longer infinite. Instead of our 'guess accuracy' being effectively 0, it's 1/<list length>.
If there are 3 billion, we might be 3 billionth, but if there are 2 billion, we are definitely not 3 billionth. The same follows all the way down to if there are only two, we may be either first or second. We know that there is at LEAST one, so if we guess first, we're at least certainly not guessing out of range.
The probability, without any other information to the contrary, of us being 'first' is higher than the probability of us being 'second' or any other possible point on the list.
Therefore it is a more logical conclusion—although clearly it should not be parroted as a fact.