Is there evidence of aliens?

[Technical Ben]

Yakk, there is 1 murder. The frequency of a single murder does not mean we can calculate how many future/existing/past murders there are (see the extrapolation comic ). The fact we find 1 murderer, does not mean we will find multiples.

Besides, murder comes after the event involved with Bob. With the life on planets people seem to be asking to arrest Bob before a murder is detected, based purely on statistical analyses. With the earth/extra terrestrial life probability, we have not seen any events. We have seen a murder done by Bob and concluded Yakk is a murderer. Why? Because there is around 1 in 7 billion chance you are. Are those two statements not contradictory? Or would you suggest you are a murderer, because Bob was? The same contradiction seems to be being used for extra terrestrial life.

To me, a "maybe" is still a "maybe" until it's very close to a "definite". Are we even 50/50 on our chances of discovery yet?

The probabilities can indicate how probable it is to find life, or where to look. But until we do find it, they are just probabilities. Things like the Higgs Boson are direct enough observations. However we are not doing the same kind of observation with exoplanets (yet ).

[edit, PS, it's late and I should probably call it a day]

[curtis95112]

Besides, murder comes after the event involved with Bob. With the life on planets people seem to be asking to arrest Bob before a murder is detected, based purely on statistical analyses. With the earth/extra terrestrial life probability, we have not seen any events. We have seen a murder done by Bob and concluded Yakk is a murderer. Why? Because there is around 1 in 7 billion chance you are. Are those two statements not contradictory? Or would you suggest you are a murderer, because Bob was? The same contradiction seems to be being used for extra terrestrial life.

You do realize that nobody here is arguing that evidence for claim X means that claim X must be true?
You can have a fantastically unlikely scenario and still have some evidence for it.

[gmalivuk]

New personal policy for this discussion: I will not read any post by someone who claims anyone else here has said aliens "must" exist".

That's not the only straw man people like Technical Ben have used, but it is one of the most frequent and easily identified.

[morriswalters]

Interesting reading on Science Daily so I'll use one of their articles for an example. Here's an excerpt of an article.

The astronomers analyse the faint earthshine light to look for indicators, such as certain combinations of gases in Earth's atmosphere [2], that are the telltale signs of organic life. This method establishes Earth as a benchmark for the future search for life on planets beyond our Solar System.

Now this type of evidence would knock my socks off. These type of observations would increase my confidence that extra solar life exists. They have identified a metric that will produces observations that that could identify characteristics of the atmosphere that would be produced by a planet with life. When we actually have sensors that will allow it. I already believe life is possible elsewhere, with the operating phrase being believe. I don't think that anyone is saying they have evidence of the existence of extra solar life. What I do believe is that there is an overly optimistic idea of what constitutes weak evidence. I believe in sensors. I like more than one data point. I don't like manipulating statics as a means of supporting a position. Now if I was funding Science I would fund ideas that are measurable. Like SETI or like the tech in the article. I like the Harp observations because they are sensor based and they are able to push them to the limits.

Actually, we have been gathering information about the probability of life occurring here for centuries. There are experiments going on in multiple disciplines that impact our knowledge of how likely life is to form on an earth-like planet. For example, our knowledge of the solar system gives us some really rough estimates of how likely that life would form. Experiments where we stick some sterile building blocks in a sealed container and see if life spontaneously generates generate upper bounds (really really rough ones) on how likely it is. Other experiments, where we work out self-assembly of the building blocks of life from substances we know to be common in the universe give us lower bounds on how likely really primitive forms of life are to form. Computer simulations of self organizing and replicating systems give us information theoretic understandings of how such systems can come to pass from chaos.

Yakk to the best of my knowledge none of these experiments have actually created anything that looks like life is the correct? On any level. So you propose to use this research as a basis to make a claim as to the plausibility of life somewhere else? Is that what you are saying? In the very set of articles on extrasolar planets on Science Daily was one who suggested that life could have arrived here on a passing rocky planet, how does that fit in?

I think it is you and the rest that don't get it. The fact that life exists here at all supplies sufficient plausibility for me to say that life could exist elsewhere. Nothing said to this point that would raise the degree of plausibility for me over that. Some real data might. Say an opportunity to get some samples back from Mars so we could do some tests with better granularity. Perhaps the planet discovered by the Harp sensors which seems to be a large rocky planet in the Goldilocks Zone with detectable water, once we have better sensors to look at it with. Or perhaps the lichen that someone is looking at that went for a ride in space for a long period of time that survived full exposure to hard vacuum as well as full sunlight which could prove that it would be possible for life to spread via orphan planets. Talk about plausibility all you want, you'll hear no more from me. Here that is, although I might spread some rain elsewhere.

[Dopefish]

As a weaker thing then people having suggested that whatever implies aliens "must" exist, has anyone even said that there's "good" evidence for aliens?

I don't think so, but theres been a lot of people correcting each other so maybe someones original claim of such has slipped through the cracks.

Is there anything that doesn't qualify as evidence based on the more general usage of 'evidence' here? ("Aha! I've observed something in the universe, and that something wasn't an alien! I am now marginally less surprised if the next thing I observe also isn't an alien! Hence, that observation was evidence against the existence of aliens!")

If there isn't anything that doesn't qualify as evidence of some sort, then the discussion is kindve pointless in that the answer to the threads subject is "yes", but such an answer probably not the spirit of the thread, and besides that leads to arguments presumably arrising from not accepting your definition of evidence. If there is some level of non-trivial-ness required for something to qualify as evidence, it's probably worthwhile to make clear exactly where that line is.

I feel like the more interesting question isn't "Is there evidence of aliens?", but rather "Is P(Aliens|Everything we know)>P(Not Aliens|Everything we know)?" which I don't think is objectively answerable either, but it seems less susceptible to people argueing over how to define evidence, and instead shift the focus to arguing the weights of various things we know for either side. As it is, I feel like at least some people are interpreting a "yes" answer to the first question as a "yes" to the second, which I'm pretty sure isn't what people are intending.

[gmalivuk]

Nothing said to this point that would raise the degree of plausibility for me over that.

This is completely irrational, on par with saying it's no more plausible that someone with a million lottery tickets will win than that someone with only one ticket will win. We have found lots of other planets. That *is* real data. It's not *strong* evidence, but it is evidence that, in a rational brain, should raise the plausibility of aliens existing. Just like buying more lottery tickets should raise the plausibility that someone will win.

Sure, it might turn out to be the case that there's some other ingredient that none of those planets have, just like it might turn out that, for some reason, all the tickets a person is buying have the same number. But without knowing that, it would be irrational not to increase our plausibility estimates in light of the number of planets/tickets we've discovered.

I feel like the more interesting question isn't "Is there evidence of aliens?", but rather "Is P(Aliens|Everything we know)>P(Not Aliens|Everything we know)?" which I don't think is objectively answerable either, but it seems less susceptible to people argueing over how to define evidence, and instead shift the focus to arguing the weights of various things we know for either side. As it is, I feel like at least some people are interpreting a "yes" answer to the first question as a "yes" to the second, which I'm pretty sure isn't what people are intending.

No, it's definitely not. Which is to say, really, that I think all those things are "no".

No, given what we know P(aliens) is not greater than P(not aliens).
No, a "yes" to the first question is definitely not a "yes" to the second.
No, that is definitely not what anyone here is intending to say, at least not recently. Though it is a weaker form of the straw man I've decided to stop replying to.

[Technical Ben]

Sorry, the lottery is an example of the core of the problem I see with the evidence. In the lottery example (a great one, as it's about the real maths here!) what is the distribution of lottery tickets?

There are a million lottery tickets. I cannot state "this makes it more probable I win" unless I also state "I buy them with an even (or fair) distribution of numbers". Currently, I see nothing to suggest if or if not the tickets are all 1 million times "1, 2, 4, 5, 6, 7". At which point the chances are the same as buying 1 ticket.

With the extra-terrestrial life problem, I see lots of planets (lottery tickets). But I've not yet seen the evidence that there are more tickets than possible winning numbers, or that there is more than one winning ticket.
The numbers don't add up just yet.

[TheGrammarBolshevik]

I cannot state "this makes it more probable I win" unless I also state "I buy them with an even (or fair) distribution of numbers".

Not true. It makes it more likely that you win so long as there is non-zero probability that you buy a ticket with a different number from the first one.

[gmalivuk]

And even if we do state that they're randomly chosen numbers, the point still stands: this obviously increases the plausibility of a win, even if it turns out after the fact that the winning lottery number was unfairly chosen to be different from all the tickets you bought (or if it turns out the winning number had already been chosen and turned out not to be any of the ones you bought, but we didn't know this at the time we counted your tickets).

[Iceman]

I think we've made a fundamental shift in language and tone.


We're now discussing plausability and possibility much more than Evidence.

I don't think anyone was denying that many factors increase how plausable or believable it is.

But that's not evidence.

It's perfectly plausible that Lindsay Lohan got arrested for DUI yesterday, but it didn't happen. It being plausible and believable isn't actually evidence it happened.

I very much disagree that 'Evidence' is interchangable with possibility, probability or plausability. It's a very different concept to me.

[gmalivuk]

I very much disagree that 'Evidence' is interchangable with possibility, probability or plausability. It's a very different concept to me.

It's a very different concept to everyone, which is why no one is interchanging the two.

We are saying that evidence is data that changes the plausibility of a claim.

[curtis95112]

Then would you suggest a better definition? Preferably one not employing an arbitrary cutoff at some given level of plausibility increase.

[Just a Geologist]

It all comes down to belief and science. Science cannot disprove or prove extraterrestrial life so some will jump to belief. All the same, you think what is or what is not will always be based on your belief.

[gmalivuk]

at some given level of plausibility increase.

I don't think Iceman et al. even understand that it's plausibility *increase* we're talking about.

[Iceman]

at some given level of plausibility increase.

I don't think Iceman et al. even understand that it's plausibility *increase* we're talking about.

I most definitely understand that's what you are talking about.

I do not view that as Evidence in cases when you're not familiar at all with initial probability.

But yes, if you want to expand the definition to explicitly include that...obviously yes more of any factor in life creation increases its plausability. So if you call that Evidence, then it is.

I'd just contest that definition as far too inclusive. It's generated from no observation of the cause of or result of Aliens, and is based of a completely unknown original probability.

While I tend to not like getting all dictionaryish: Evidence tends to prove or disprove something, and or is a signal or indicator of something.
None of this would serve as proof, and none of this is an indication of something.

It's just the acknowledgement that it could happen, and could happen more the more compatible conditions exist. None of that is an indicator or proof it IS happening.

[morriswalters]

gmalivuk that's not a useful story. The TheGrammarBolshevik points to the problem. Buying two lottery tickets changes the odds of winning. But the odds are so high that in any real sense the odds of winning with two tickets is practically the same as one. You can't change the odds enough to make it reasonable to play if you need to win. Any additional plausibility or confidence that you buy is meaningless if the idea is to find life. Finding planets proves that there are extrasolar planets, finding them in the Goldilocks Zone proves they are in the Goldilocks Zone. We don't need plausibility, we need data.

[gmalivuk]

We don't need plausibility, we need data.

Please explain what you mean by "data", which doesn't include the number or location or other characteristics of planets.

[Iceman]

gmalivuk that's not a useful story. The TheGrammarBolshevik points to the problem. Buying two lottery tickets changes the odds of winning. But the odds are so high that in any real sense the odds of winning with two tickets is practically the same as one. You can't change the odds enough to make it reasonable to play if you need to win. Any additional plausibility or confidence that you buy is meaningless if the idea is to find life. Finding planets proves that there are extrasolar planets, finding them in the Goldilocks Zone proves they are in the Goldilocks Zone. We don't need plausibility, we need data.

You have A Lottery ticket with 'X' numbers on it.

I tell you the first 5 numbers on your ticket match.

You don't know how many numbers remain on the ticket, or how they are drawn.

I tell you the 6th number also matches. I've increased the probability of your ticket winning.

Can you quantify or even estimate by how much? Is the increase meaningful to us with no idea what other pre-conditions exist?


All we're doing is laying out pre-conditions to life potentially forming.

The only one I've seen that serves as a cool indicator life may exist is the O2 not forming without life thing. I haven't been able to find out if that's true or not, but if O2 was the result of life, if it was a thing we found and couldn't explain normally, but life was a decent explanation....THAT could be evidence.

[gmalivuk]

I tell you the 6th number also matches. I've increased the probability of your ticket winning.

Can you quantify or even estimate by how much? Is the increase meaningful to us with no idea what other pre-conditions exist?

Regardless of the answer to these questions, the second of which is purely subjective anyway, I would still use "evidence" to describe the observation that the 6th number also matches. It increases the plausibility that your ticket is in fact a winner. It decreases how surprised we should be to find out that it is in fact a winner.

[curtis95112]

@Iceman
Why the emphasis on initial probability? We know that the plausibility increased, whatever it was initially.

@morriswalters
Thing is, none of the examples of "evidence" that you give make it certain that claim X is true. This is to be expected, of course, since we can't prove anything beyond all doubt. All we can do is find enough information to increase the plausibility of X until we can, for all practical purposes, take it as true.
Given that we can't "prove" anything anyway, and that the quality of evidence is a matter of degree, it makes sense to include all information that increases plausibility. If you disagree, please tell me where you feel that the cutoff should lie and why.

Also, about the O2 thing. The conditions you give (life is a decent explanation, we can't explain it normally (w/e normally means))*, seem to be conditions for rationally preferring the hypothesis that there is life over other hypotheses. I fail to see why you set such a high standard for evidence, and would like to note that this particular standard depends on the quality of other hypotheses.

[Iceman]

@Iceman
Why the emphasis on initial probability? We know that the plausibility increased, whatever it was initially.

Because we haven't gained anything.

X * 2 = ?

The evidence the 6th number matches only tells you the 6th number matches. In this case, it gives no actual insight into whether or not the ticket will win.

Bringing in 'Plausability' is more about how believable it is to you, and driven by our misunderstanding of what we don't know.

In a sense the moment Evidence started meaning 'Things that make it more plausible' then this thread became a tautology, but everyone's apparently now adopted that language.

I think there's a word or two missing in the O2 question. But you wouldn't have to prefer anything over anything. If its true that nothing we currently know explains O2 in atmospheres except life...or if Life is one of the things that explains it, and we see cases where the other things that explain it aren't present, or its occurring a rate higher than would be predicted by the other things....than that would be evidence.

That is not a high standard of evidence at all, but it's also not a total abandonment of what the word means, which I think we've essentially done in the last page or so.

I mean, how gmalvik chooses to use it, doesn't mean its a proper use. I could use the world Pineapple to refer to a Duck if I felt like it, he's said he's using it in a fairly expansive way.

[Yakk]

I tell you the 6th number also matches. I've increased the probability of your ticket winning.

Can you quantify or even estimate by how much? Is the increase meaningful to us with no idea what other pre-conditions exist?

Regardless of the answer to these questions, the second of which is purely subjective anyway, I would still use "evidence" to describe the observation that the 6th number also matches. It increases the plausibility that your ticket is in fact a winner. It decreases how surprised we should be to find out that it is in fact a winner.

I've heard (once) the term "Bayesian Power" used to reflect the fact that you can describe how much evidence something is towards something being true, without knowing what your prior distribution was. It doesn't seem to be in general use.

Ie, you have:
P(A|B) = P(B|A) * P(A) / P(B)
where your prior probability is P(A). We can then express Bayesian Power as:
P(A|B)/P(A) = P(B|A)/P(B)

So you learn some new fact B. The probability that you'd learn the fact B is P(B), and the probability that B is true given that A is true is P(B|A). P(B) is how surprising this fact is, given your previous information, and P(B|A) is the odds that B would be true if you assumed A is true.

This still means we need to know something about the universe, but it means we need to know less about our estimate for A being true. We still need to know something about our prior belief that B was true, and how likely we'd see B if we assumed A is true, but that can be easier to work out.

If you don't know enough to calculate some of these probabilities, you can produce ranges to bound the amount of Bayesian power a given observation generates.

The English version of this is "how much more likely X is true assuming Y is true is also how much more likely Y is true given X is true."

Note that these probabilities don't multiply together. If you know that B and C are true, and the Bayesian Power of B is 5 and the Bayesian Power of C is 10, the Bayesian Power of B and C isn't 50.

[gmalivuk]

In a sense the moment Evidence started meaning 'Things that make it more plausible' then this thread became a tautology, but everyone's apparently now adopted that language.

Yes, because we can still discuss the more interesting questions of "how much evidence is there" or "how good is the evidence".

[morriswalters]

We don't need plausibility, we need data.

Please explain what you mean by "data", which doesn't include the number or location or other characteristics of planets.

Signs that point to life, for instance atmospheric composition that would indicate industrialization, or quantities of free oxygen in quantities consistent with life. Measuring the second over a long enough time base could give us data that would eliminate one time only events since currently we are seeing snapshots only. The first would give us reasons to expend effort to look at the radiation given off by the target. We are looking at one subset of possible targets, and that is targets that could exhibit effects we can see. Planets are useful only because they are someplace we can look at that we can see. Finding the planets and seeing the characteristics of the planets becomes useful only when we see a phenomena that can't be explained by the existence of the planet. That is the data we are looking for. The thing you are talking about supports where to look, not what you will see when we look. And our sensors aren't that good yet, are they?

I tell you the 6th number also matches. I've increased the probability of your ticket winning.

You've done nothing. The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

I'll try to be explicit. We look at the Goldilocks Zone because it is a orbital location where water is a liquid. We know that life as we know it needs water. However this neither increases or decreases the probability of life there. We are looking looking in the first place because we expect to see it there. What increases our knowledge is something which isn't explained by the reason we looked. Something in addition to water or the orbit. -Sigh-

[Iceman]

I tell you the 6th number also matches. I've increased the probability of your ticket winning.

You've done nothing. The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

I'll try to be explicit. We look at the Goldilocks Zone because it is a orbital location where water is a liquid. We know that life as we know it needs water. However this neither increases or decreases the probability of life there. We are looking looking in the first place because we expect to see it there. What increases our knowledge is something which isn't explained by the reason we looked. Something in addition to water or the orbit. -Sigh-

Ya, that was my point. You snipped that out of context. It does increase the probability, by a useless, undefined amount, so for all practical purposes, it didn't.

In a sense the moment Evidence started meaning 'Things that make it more plausible' then this thread became a tautology, but everyone's apparently now adopted that language.

Yes, because we can still discuss the more interesting questions of "how much evidence is there" or "how good is the evidence".

Seems like a completely different topic, If you're now just talking about how many factors exist that allow life. Just feels like you've re-defined a word until the problem went away.

[gmalivuk]

The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

No shit. And *given* that it matches the first six, the probability that it matches all of them is higher than the prior probability that it matches all of them.

[Iceman]

The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

No shit. And *given* that it matches the first six, the probability that it matches all of them is higher than the prior probability that it matches all of them.

But not as far as you know, and there's literally instances where it is not. If the odds of any number in the Chain of X matching yours is 0, then the probability has not increased.

So no, you can't even say that factually.

[curtis95112]

I think there's a word or two missing in the O2 question. But you wouldn't have to prefer anything over anything. If its true that nothing we currently know explains O2 in atmospheres except life...or if Life is one of the things that explains it, and we see cases where the other things that explain it aren't present, or its occurring a rate higher than would be predicted by the other things....than that would be evidence.

That is not a high standard of evidence at all, but it's also not a total abandonment of what the word means, which I think we've essentially done in the last page or so.

If life in one thing that explains it, and the other explanations aren't sufficient. Life is the best hypothesis we have. You're still saying the same thing. I continue to hold that this is far too high a standard for evidence. We can have evidence for competing theories.

The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

No shit. And *given* that it matches the first six, the probability that it matches all of them is higher than the prior probability that it matches all of them.

But not as far as you know, and there's literally instances where it is not. If the odds of any number in the Chain of X matching yours is 0, then the probability has not increased.

So no, you can't even say that factually.

Now you're giving real-life scenarios a probability of zero? I don't think you can do that. All scenarios have a nonzero probability given anything less than perfect information.

[gmalivuk]

The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

No shit. And *given* that it matches the first six, the probability that it matches all of them is higher than the prior probability that it matches all of them.

But not as far as you know, and there's literally instances where it is not. If the odds of any number in the Chain of X matching yours is 0, then the probability has not increased.

So no, you can't even say that factually.

Now you're the one using words strangely.

If I know literally nothing about how the other numbers were chosen, I should still consider it less surprising to win given that the first six match than given that the first five match. Maybe the next number in the winning combo is 3, and the next number on my ticket is 2, and so I for sure definitely did not win. But *before* knowing that, I should consider it more plausible with 6 matches than with only 5. (Assuming that there is more than one option for the 6th number, of course.)

[Yakk]

Iceman, why do you think you know enough about probability to justify strong opinions on the matter?

morriswalters, why do you think you know enough about probability to justify strong opinions on the matter?

You appear to be both Dunning-Kruger-ing. Your level of expertise isn't sufficient to let you realize you are making statements about probability that are both way too strong for your level of expertise, and (as it happens) incorrect. You lack the expertise in understanding probability to realize you are incompetent at understanding probability, so you think your opinions on probability are just as good as anyone else's, and that you are competent at understanding probability.

Have you taken even an introductory course on probability? Did it cover Bayesian probability? If not, you should possibly think "maybe I don't understand probability as well as I think I do"? Maybe?

Examples of such statements:

I tell you the 6th number also matches. I've increased the probability of your ticket winning.

You've done nothing. The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

The response above is simply false in the context of Bayesian probability, which I'm pretty sure Gmal has repeatedly stated he's using. Gmal has been quite clear how he's using terms like probability.

If you want to make a philosophical position against Bayesian based probability itself, then feel free. But you should do so explicitly. And I'd advise learning what it is you are disagreeing with before you start saying it is wrong?

[Iceman]

The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

No shit. And *given* that it matches the first six, the probability that it matches all of them is higher than the prior probability that it matches all of them.

But not as far as you know, and there's literally instances where it is not. If the odds of any number in the Chain of X matching yours is 0, then the probability has not increased.

So no, you can't even say that factually.

Now you're the one using words strangely.

If I know literally nothing about how the other numbers were chosen, I should still consider it less surprising to win given that the first six match than given that the first five match. Maybe the next number in the winning combo is 3, and the next number on my ticket is 2, and so I for sure definitely did not win. But *before* knowing that, I should consider it more plausible with 6 matches than with only 5. (Assuming that there is more than one option for the 6th number, of course.)

But that's your belief.

Your belief is not actually justified. It's more plausible to you, it doesn't make it more probable. If some other element is 0, then your belief would be wrong.

Iceman, why do you think you know enough about probability to justify strong opinions on the matter?

Like real world qualifications you mean? I do have a Master's degrees and manage risk for an Options and Futures portfolio....but none of these things would be required to have this opinion. I don't think you'd need much education beyond junior high school to be aware of the math involved.

Something times 0 is 0. An undefined number times anything is undefined.

You on the other hand literally read as if you just read something and cut and paste it out of context in a thread.

Nothing I am saying in this entire thread ever mentioned, referenced, refuted or addressed in anyway Bayesian theory, which simply doesn't apply here.

You also just quoted someone else and acted as if I said something.

I don't think you have a single clue what you're talking about. You latched onto a term you don't get on about page 2, and you've just repeated it alot. You then bounce back and forth between math and philosophy for no apparent reason...

Then to somehow resort to personally attacking my education...I don't even understand.

I don't know what you're even saying is the case, you're literally just saying words you found on Wikipedia.

[curtis95112]

But the prior isn't zero. It can't be. It isn't undefined either, it's unknown but definitely defined.

[Iceman]

But the prior isn't zero. It can't be. It isn't undefined either, it's unknown but definitely defined.

It actually could be zero.

So yes, The reality could be zero, and to you as the observer, it's undefined.

If there do not exist conditions to create Alien Life, then it's zero. There could be a state such that the conditions to create life happened explicitly one time.

[Technical Ben]

Plain and simply try cashing a lottery ticket with 5 winning numbers, and the rest "I did not look at yet, please don't look, because until I look I class it as evidence I won".

I class evidence as synonymous with having all the winning lottery numbers. We can check this in mathematics, probability etc. Is this correct?
Probability, suggestion, theory etc all come in the "close to having all the numbers" or "all the numbers so far". You've not won yet. That does not mean you will not, but you can still loose.
Against other players, you are probably winning though. But is not what is being contested, but that it's a definite win already is what is being contested.

So perhaps "Is there more evidence for aliens" is a correct statement. But compared to what? Here I only know of the two theories. One for and one against. Can we cite which is the strongest supported theory? Can we consider evidence in a vacuum?

So far, I see nothing in the search for ET that matches the life on earth or life in general. Is there evidence (matches) for the precursors of life? Possibly. For the planet earth? Close. To increase the probability? Defiantly.

[morriswalters]

Here's the quote.

You have A Lottery ticket with 'X' numbers on it.

I tell you the first 5 numbers on your ticket match.

You don't know how many numbers remain on the ticket, or how they are drawn.

I tell you the 6th number also matches. I've increased the probability of your ticket winning.

Can you quantify or even estimate by how much? Is the increase meaningful to us with no idea what other pre-conditions exist?

Iceman I state this because someone has chosen to make a point of it. Unless your voice can rewrite the ticket it doesn't change anything. The answer was determined when the ticket was printed. The probability of a winning ticket is the probability stated by the rules. It's fixed. You can't do anything to change it, period. I don't say this to be rude and if it seems that way I am sorry.

The probability of me winning is related to my knowing that I have have a winning ticket, the probability of my ticket being a winner is a product of matching all the winning numbers.

No shit. And *given* that it matches the first six, the probability that it matches all of them is higher than the prior probability that it matches all of them.

Now gmaliuvik back to you. In a period of time when you weren't busy thinking that I am a fool, you would realize that your response as quoted is counter factual. It may get my hopes up and I may pee myself in excitement, or even have a heart attack, but nothing you or I or Iceman can do can change that number. The event we are interested in has already happened. The number is printed and the draw has been made. The only thing in doubt is the question of our knowledge of the fact that we have a winning ticket. The probability that you are quoting is the probability of draw(I suppose), and we don't care about it. The ticket is an all or nothing thing, it either matches or it doesn't. It doesn't matter how you expose the numbers.

As the discussion seems to be going to places I'm not interested in, I'll exit. If anyone is interested in anything I have to say PM me.

[curtis95112]

Yes, if you have perfect information, everything is either zero or one. But you don't. You can't have exactly zero confidence in a claim without perfect information.
Also, do you know what the word "defined" means? What does it even mean for a probability to be undefined?

I'm sorry, but you keep twisting the words and going back and forth between the probability of alien existence, which we are talking about, and the reality of alien existence, which we are not. We don't know if aliens exist, that doesn't stop us putting a probability on it.

If there do not exist conditions to create Alien Life, then it's zero. There could be a state such that the conditions to create life happened explicitly one time.

So please, cut this sort of thing out. This assumes perfect information, which we do not have. If we did, we wouldn't be using probabilities.
You're basically claiming that there is a nonzero probability that aliens can't exist, which isn't disputed by anybody, and then mangling the phrase to say, in effect, "there is a nonzero probability that the probability of alien existence is zero", which might sound halfway convincing but is just as vacuous as the previous claim.

EDIT @ morriswalters:

Go look up Bayesian probability. You're doing the same thing as Iceman by misusing the word probability. Do you realize that incomplete information will always give you a probability between 0 and 1? Do you also realize that one can update one's confidence in a claim after obtaining new information? Do you realize that what you are saying is so horribly wrong that it's nonsensical?

[gmalivuk]

Plain and simply try cashing a lottery ticket with 5 winning numbers, and the rest "I did not look at yet, please don't look, because until I look I class it as evidence I won".

Yeah, I'm going to ignore you in this thread until you demonstrate that you know what the rest of us are talking about.

(In particular, that you know no one else is talking about what "must" be the case.)

[Iceman]

Here's the quote.

You have A Lottery ticket with 'X' numbers on it.

I tell you the first 5 numbers on your ticket match.

You don't know how many numbers remain on the ticket, or how they are drawn.

I tell you the 6th number also matches. I've increased the probability of your ticket winning.

Can you quantify or even estimate by how much? Is the increase meaningful to us with no idea what other pre-conditions exist?

Iceman I state this because someone has chosen to make a point of it. Unless your voice can rewrite the ticket it doesn't change anything. The answer was determined when the ticket was printed. The probability of a winning ticket is the probability stated by the rules. It's fixed. You can't do anything to change it, period. I don't say this to be rude and if it seems that way I am sorry.

I'm obviously referring to your awareness of the probability. If you take this extreme literal stance, than nothing has a probability at all, that's just kind of silly to say unless you believe we live in a deterministic universe, which it seems we do not.

So please, cut this sort of thing out. This assumes perfect information, which we do not have. If we did, we wouldn't be using probabilities.
You're basically claiming that there is a nonzero probability that aliens can't exist, which isn't disputed by anybody, and then mangling the phrase to say, in effect, "there is a nonzero probability that the probability of alien existence is zero", which might sound halfway convincing but is just as vacuous as the previous claim.

But this is precisely why I'm saying it isn't Evidence. You can literally use the argument to provide 'Evidence' for both sides. They are equally valid.

you construct a probability based argument over Aliens existing, and you've automatically created an argument for them not existing. You can't call either one evidence.

[Just a Geologist]

You all are talking about probability. With this in mind, how many galaxies are there? With in those galaxies, how many stars have planets orbiting them? Of those planets, what is the probability of life?

[Yakk]

Sorry Iceman. I misread some of your posts, and was frustrated.

Yes, given what gmal typed, he could have had a prior probability of 0 that he won in a theoretical model, and thus knowing that any given one matches would not increase the probability that he won.

In practice, no, you cannot actually have a prior probability of 0 that you won a lottery. You can have a really small one, but 0s don't happen[1].

You also just quoted someone else and acted as if I said something.

No, I was speaking to two people in a post. And gave an example of what I was talking about. The quote in question wasn't from you, but it wasn't attributed to you as far as I can tell. You wheren't even the nearest person who was named prior to the quote.

Iceman, why do you think you know enough about probability to justify strong opinions on the matter?

Like real world qualifications you mean?

Naw. I'm just wondering why you think you know enough about probability to justify strong opinions on the matter. And you seem to have strong opinions on the matter.

Something times 0 is 0.

True. But probability is rarely zero. Physics doesn't have many zeros.

I suppose you could be a strict frequentest and state that P(X) is always 0 or 1 for any concrete statement about the universe X. If it isn't 0 or 1, it is because you where insufficiently specific about your X.

That would be an example of a philosophical objection. In that case, you'd be arguing semantics, stating that Bayesian probability is an invalid use of the term "probability": if you are doing that, you should be explicit that your disagreement is semantic.

I'm wondering if that is what is going on?

An undefined number times anything is undefined.

An unknown positive number, times another number that is greater than 1, is greater than its previous value. Even if we didn't know what it was before, and we don't know what it is afterwards.

If P(Aliens) > 0 (and our current model of physics says this is true[1]), then P(Aliens|We found planets in the goldlocks zone) = P(We found planets in the goldlocks zone|Aliens) * P(Aliens)/P(we found planets in the goldilocks zone).

And if P(We found planets in the goldlocks zone|Aliens) / P(we found planets in the goldilocks zone) > 1, then finding planets in the goldilocks zone increases the probability there are aliens out there.

Which seems like a reasonable definition for "evidence".

And no, I did not learn probability from Wikipedia.

You also just quoted someone else and acted as if I said something.

No. I spoke about two people. Then quoted the second one I spoke about.

I was frustrated, and impolite. I apologize.
[1][spoiler]So if there is a non-zero probability that a given macroscopic prediction of QM is true, and QM gives a non-zero probability of something happening, then a reasonable prior probability of that being true is greater than zero. The resulting probability will be vanishingly small: but all that is required for x*y > x where y > 1 is that x is not identically zero. Any lower bound on x is sufficient, even ridiculous ones.[/quote]