In two recent posts I discussed the question posed as to why there is something other than nothing and whether the question was even meaningful. The difficulty of showing that something does not exist is not confined to questions about the universe as a whole, it even applies to individual entities where you think it might be easier.
I got a text from a person I know and attached to it was a video of what looked like an organism consisting of the head and tail of a fish and, in between, the torso of a human being with arms behind its back and three pairs of breasts. This looked like it had been forwarded multiple times on social media and this person asked me if I thought it was real. I replied that it is safe to assume that anything seemingly bizarre that floats around the internet, and is not cited to a reputable news source along with supporting evidence, is a hoax. I did not tell him it was impossible that it was real because such a level of certainty implies omniscient knowledge on my part. But it is possible to be effectively certain that some things do not exist if one follows the logic of science.
On a recent episode of This American Life, they had a segment on investigations into Unidentified Aerial Phenomena (UAP) that were formerly referred to as UFOs. Although investigations showed that the ones that could be studied had mundane explanations like weather balloons, reflections off surfaces, camera-introduced effects and the like, it will never be possible to convince believers that extraterrestrial (ET) are not visiting us because new examples are continuously brought up. So in the debate over whether ETs are visiting us or not, it seems like the only possible definitive answer will be an affirmative one (if ETs were to actually make contact with us) while a definitive negative answer would forever remain elusive because however many cases are debunked, believers would never cease to have new cases to be investigated and thus could never ‘lose’ the argument. That seeming lack of ability to conclusively rule out the existence of an entity applies to any and all entities however absurd, like the fish-human hybrid sent to me, which is why we also have never-ending ‘debates’ about the existence of the Loch Ness monster, the Yeti, ghosts, vampires, and the like.
And yet, in science, we seem to be able to definitively say that some entities do not exist. We have done so with the aether, phlogiston, N-rays, etc. The ability to do so is a major part of the reason for science’s success since it prevents us from wasting time interminably debating the existence of spurious entities. The reason we can do so in science but not with things like UAPs is not because the entities in science are fundamentally different from things like UAPs but because in science we use the logic of science that includes decision rules that allow us to make definitive judgments. These decision rules depend upon the nature of the assertion (whether it is an existence claim or a universal claim) and where the corresponding burden of proof lies.
If someone makes an existence claim of an entity, the default position is nonexistence and the burden of proof is on that person to provide a preponderance of evidence in support of existence of that entity. Failure to do so implies nonexistence. For a universal claim (that, say, all electrons have the same mass), the default position (once some evidence in support of the claim is established) is that the claim is valid and the burden of proof is on the person challenging the claim to provide a preponderance of evidence that there is an exception to it. Failure to do so implies that the claim is valid. That is how scientific laws (which are universal claims) are established, because of the lack of credible evidence of a violation.
This logic and rules have close parallels with the reasoning used in the legal world to arrive at verdicts. It is the use of those rules that enables us to say with extremely high degrees of confidence that some things do not exist and that some laws always hold. This is why scientists tend to be skeptical of all supernatural claims, including the existence of gods, because there has never been a preponderance of evidence in favor of the claim.
The interesting thing is that scientists absorb the logic of science and the associated decision rules largely unconsciously during their training and practice and hence are often not explicitly aware that they are using them. This does not cause any problems within the world of science since all practitioners share the same implicit worldview but can result in frustration when they engage with the general public that does not share them. If people explicitly recognize the decision rules used in science and use them to adjudicate issues of existence and nonexistence of all entities, it is straightforward to conclude (with the same degree of certainty that the aether does not exist) that UAPs, ghosts, vampires, and gods do not exist either, thus saving us all a lot of time.
This has implications that extend well beyond things like UAPs which are, after all, fairly trivial matters. It has much more significant consequences when it comes to major issues such as climate change, the efficacy of vaccines, the dangers of smoking, and so on. Skeptics in these areas use the general ignorance of scientific logic to sow doubt as to the reliability and robustness of the scientific consensus in those areas. While they are perfectly happy to enjoy the tremendous benefits that science has provided, they are quite willing to jettison the very reasoning that science uses to obtain those successes when it leads to conclusions that are uncongenial to them for whatever reason. It is very important for public policy (especially in this age of anti-science sentiment) that we increase public awareness of the decision making rules used in science, and use them consistently, in order to make better policy decisions.
The argument that I have sketched out here is developed more fully in my book THE GREAT PARADOX OF SCIENCE: Why its conclusions can be relied upon even though they cannot be proven (Oxford University Press 2019).
sci·en·tif·ic meth·od | ˈˌsīənˈtifik ˈmeTHəd |
noun
a method of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses: criticism is the backbone of the scientific method | [in plural] : the process is based on presently valid scientific methods.
https://xkcd.com/1235/
The really interesting thing about UFOs/UAPs/whatever is the fact that people persist in seeing and reporting them. It’s interesting on a psychological level. The actual objects are, literally and figuratively, mostly immaterial.
Therefore there are no other life forms , nor were there ever , in the universe ? Quite a bold claim.
… Unidentified Aerial Phenomena (UAP) that were formerly referred to as UFOs. Although investigations showed that the ones that could be studied had mundane explanations like weather balloons, reflections off surfaces, camera-introduced effects and the like…
I still maintain the updated acronym should have been UOPs -- Unidentified Optical Phenomena.
I thought Carl Sagan did an excellent job with his essay The Dragon In My Garage.
—
Deepak @4, you misunderstand the claim; the claim is not that ETs don’t exist, but rather that ETs that are visiting us don’t exist.
@John Morales
No , not really.
Me : there likely is or was life elsewhere in the universe.
Mano : Wheres your evidence?
Me : I have none
Mano: My default position is non existence . Therefore there wasnt and isnt.
The default position as stated is too broad and incorrect. The default position is “we dont know” for items not really studied and “we dont know , but unlikely” for items that we have a better idea of and “No” if it has been thoroughly studied. A good bit of “We dont know” can also be “Why should we care?”
Therefore there are no other life forms , nor were there ever , in the universe ? Quite a bold claim.
We can admit the possibility, in general, that there COULD be other life-forms out there, somewhere; or even that it’s very probable that some other life-forms exist out there, somewhere. It’s only when the claim gets more specific, and goes from “could be” to “is,” that the burden of proof kicks in. Lots of people thought there COULD be life on Mars, but then we learned more about that particular place and found no evidence that there actually WAS life on Mars. Hopefully we’ll have better luck with, say, Europa, or some of those exoplanets we’ve been seeing lately…
Deepak, “likely is” is not an existence claim; “is” is.
(cf. Russell’s teapot)
[RB, we crossed]
Actually, Deepak’s point stands. If I claim “there is life on other planets”, Mano’s formula requires that (a) the burden of proof is on me. So far so good. But the formula also includes, if I fail to provide evidence, (b) assuming the default position that there is not life on other planets. That’s just a step too far. Why does there need to be such a binary response (existence/nonexistence)? It smacks of dogmatism.
John @6: Well, if the Many Worlds interpretation holds, there could well be things in your garage which are undetectable to you (perhaps not dragons).
If I claim “there is life on other planets”, Mano’s formula requires that (a) the burden of proof is on me.
Not really, because that’s a very vague and un-disprovable claim. It’s only when you claim there IS life on a particular planet that you take on the burden of proof.
Rob @11, it’s a provisional position, amenable to being changed if new evidence emerges. That’s not being dogmatic, that’s being pragmatic.
I myself believe that life on Earth is not the only life that exists in the universe (or even in our galaxy) by applying the principle of mediocrity, but obviously it’s not something I can assert.
Raging Bee @13: There’s nothing vague about it. Would it seem less vague if I said “there is life outside the solar system”? If I picked a particular exoplanet and claimed there was life on it, would I have to specify which parts of the planet contained life?
Not sure what your point about “un-disprovable claim” is. If I claimed there was a deity who created the universe, that seems like an un-disprovable claim as well. Would the burden of proof then not be on me?
John @14: There’s nothing provisional about assuming nonexistence. The correct response is “there is as yet no evidence for that”.
So, Rob — far as you’re concerned, it may well be that Zeus exists. 🙂
So, John, as far as you’re concerned, Zeus does not exist, but it’s only a ‘provisional’ nonexistence?
Exactly, Rob.
(Only analytic propositions are guaranteed to be definitive)
@John Morales, @Raging Bee
Sigh. Fine
Me : there IS (or was) life on other planets
Mano : Wheres your evidence ?
Me : I have nothing that can be considered evidence -- but the fact that there IS life on this planet and the universe is vast and we collectively rule out the supernatural implies to me that there IS (or was) life on other planets
Mano : My default positions .. etc etc and so forth
Happy now ?
The distinction doesnt really make sense anyway. Suppose Nasa sends a probe to a planet we have not seen anything off. While everyone is saying lets wait and watch ,then everyone can have that position But as soon as someone says there will definitely be life on this planet I am sure of it!(or whatever claim one wants to make), -- we now have to switch from “Lets wait and watch” to “There Isnt!”.
Yes, I am making a strong statement but it is how we decide that some things such as ghosts and fairies do not exist. In the absence of such decision rules for existence claims, we would have to allow for the possibility of the existence of anything that the mind can conceive. But all of us rule out the existence of some things. What is the basis for such a judgment?
People can believe in the existence of anything they want because we cannot definitively prove non-existence unless it is logically impossible. But if they want to persuade others to believe in those things, they will have to provide a preponderance of evidence in support and until they do, we can assume non-existence.
As for the specific case of life on other planets, I would like to think it exists but since there is no evidence whatsoever for it, I live my life on the assumption that it does not exist, the same way I do not think that ghosts and vampires and other such things exist.
We all live our lives confident that some things do not exist even though we cannot prove their non-existence. What distinguishes those things that we believe do not exist from those that we think might exist? What is the difference between vampires and ETs?
@Mano
But these are two different things. Even if tomorrow someone finds proof that there is some single celled life on some far off planet that we cant get to , it wont make much of an impact to my life , or how I live it, no ?
If true, then you are against funding any research that attempts to look for this life , no ? I dont see why i need to ass-u-me anything. Im happy to say i dont know alongside all the other things that i dont know.
>What is the difference between vampires and ETs?
Specific claims , including what we could expect as a consequence of that claim. As John Morales has stated , that your assume non existence position is also making a specific claim -- That life on earth is unique -- Where is your proof for that ?.
Mano @21:
According to your previous paragraph (“…the same way I do not think…”) you don’t distinguish them.
The difference between ET and vampires? There is no evidence for ET, but that evidence may be forthcoming. So no, I don’t live my life on the assumption that ET doesn’t exist. There is no evidence for vampires (or Zeus) either, but there are compelling reasons to think that they are fictional. I do live my life on that assumption.
Deepak @#22,
There are different decision rules for existence claims and universal claims. Non-existence is a default inference based on the lack of a preponderance of evidence. It is not an existence claim.
I am perfectly comfortable searching for extraterrestrial life but it is a personal preference based on the assumption that such a search stretches the limits of science and technology and thus can provide us with benefits even if the search fails. I do not have the same confidence in the benefits of searching for vampires, so I would not choose to spend public money on that. But in each case, I assume non-existence until there is a preponderance of evidence in support of existence.
(https://www.bu.edu/articles/2010/real-life-vampires/)
Rob @#23,
What are your reasons for thinking that evidence may be forthcoming for ETs but that vampires (and Zeus) are fictional? At present we have no compelling evidence for the existence of either.
Would it seem less vague if I said “there is life outside the solar system”?
No, because “outside the solar system” is a huge area with lots of planets likely to exist; so that claim would still be too vague to either prove, disprove, or be useful at all.
If I picked a particular exoplanet and claimed there was life on it, would I have to specify which parts of the planet contained life?
No, someone would just have to send a probe to that planet and look for signs of life. (Of course, if you narrowed it down, that might make the search go a little faster, provided you had good reason to specify one part and not another.)
What are your reasons for thinking that evidence may be forthcoming for ETs but that vampires (and Zeus) are fictional? At present we have no compelling evidence for the existence of either.
No, but it is simply more logical to suspect there might be some (currently unspecified) kind of living things elsewhere in the Universe, than to suspect vampires or Zeus exist. Because vampires, as described in folklore, don’t make sense in the context of known biology; and none of the claims made about Zeus have been supported by evidence.
[OT + levity]
Depends on the folklore:
https://www.rifters.com/real/shorts/VampireDomestication.pdf
Mano @26:
One example;
https://arxiv.org/abs/2108.10888
I’m not aware of similarly promising studies regarding vampires, even though they supposedly live on the same planet as us.
@ 21 Mano Singham
I suspect Mano is toying with us.:-)
But I would suggest two things: consistency and predictability.
Surely science does not only consider direct evidence, but also that which is consistent which the well-evidenced framework already established. Lacking evidence for that which is consistent with well-evidenced models is surely a different thing to lacking evidence for that which runs counter to well-evidenced models.
And it could be argued that present understanding predicts the existence of extraterrestrial life, not as a certainty, but as a likelihood, since there is no known reason why the origin of life should occur only once.
The same is not true of undead bloodsuckers, or disembodied intelligences, or whatever, which are neither consistent with well-evidenced models, nor predicted.
(I’m assuming “ET” to mean any non-terrestrial life, not just anthropomorphic little green men.)
I’d argue that the question of extraterrestrial life is one which highlights a potential tension between existence claims and universal claims.
We know that life exists here, and we believe that it has arisen from the operation of physical laws which we assume to be universal. The question then becomes whether the existence of life elsewhere in the universe is a fresh existence claim, or whether the non-existence of life elsewhere in the universe is a violation of a universal claim.
I would argue that the default position should be that, if life is the product of the operation of universal physical laws, we should assume that it does exist elsewhere, and that the burden of proof should lie on those who claim that this particular planet is somehow unique in the Universe.
I think Mano got this one only partially correct. I’d describe it this way:
1. The default position is either “we don’t know” or “everyone knows X”.
2. Someone makes a claim: they now carry the burden of proof of that claim.
3. If the proof is convincing, the default position changes to their claim. If not, it stays as before.
4. It makes no difference if the claim is positive or negative, and universal or not.
What changes is that for non-universal (existence) claims, you have to demonstrate (at least) one example that follows your claim; for universal claims, you have to convince people that every example follows your claim.
In this case, a claim that a universal doesn’t hold is actually an existence claim (for a counter-example).
Sometimes, it is possible to demonstrate a universal by showing that counter-examples are actually not counter-examples, which can be easier (if true).
@ 15 John Morales
I think we’re all in agreement that if there’s one principle for which we should defer to your expertise, that’s the one.
Dunc @31:
I don’t see why, in cases like this, there has to be a binary default position at all. As with many other unresolved issues, I see it as “open”, without any need for assuming (even ‘provisionally’) either existence or nonexistence a priori.
Rob @#34,
It is possible to have just two alternatives in response to an existence claim: either existence (if a preponderance of evidence has been provided in support) or, in the absence of evidence, permanent agnosticism, that it may exist but we don’t know.
But note that consistency requires one to use that for any existence claim, however ludicrous we may think it is, say fairies or ghosts or werewolves and such.
But in science, we confidently do say that some things do not exist, such as the aether or phlogiston. What would be the difference?
I am saying that we should use the same decision rules that we use to exclude entities in science to those entities that we hear about in the everyday world.
Dunc @#31,
A statement that life exists on some other planet is an existence claim. The statement that no life exists anywhere else in the universe is a universal claim. In both cases, overruling the default position requires a preponderance of evidence in support of the existence of life, as khms @#32 says.
@Mano
But lack of preponderance of evidence is only after you have looked . Given that we have somewhat seen N planets and there exist M planets and N < M by a huge margin , you have no basis to claim lack of a preponderance of evidence. Your default inference as such will/should prevent you from looking for this evidence too.
Also this "default inference" is neither a scientific position (Did people say their default inference is there is no Higgs boson till there was definitive evidence for it?) , nor a (proven) philosophical one -- And is one not even borne out as an accurate one by history.
…or, in the absence of evidence, permanent agnosticism, that it may exist but we don’t know.
That may be a sound philosophical/theoretical position, but on the practical-decision-making level, it’s utter crap, because it would require us to exhaust all of our time, energy and resources preparing for all manner of imagined events, just because we don’t know FOR SURE that they won’t happen. Do we know for sure that there isn’t an aggressive galactic empire that will one day conquer our solar system? No. Does that mean anyone would suggest that we spend more tax revenue building a space-fleet to fight this empire? Fuggedaboutit — for all practical purposes, we act as if we KNOW that no such empire exists.
And that’s not even touching on how religious apologists use that reasoning to insist that no one can ever be certain their god doesn’t exist, therefore atheism is irrational and we all have to be spineless agnostics in the face of their unshakable certainty.
Deepak @#37,
We have a preponderance of evidence for the existence of many planets. We do not have a preponderance of evidence for the existence of life on those planets. As I said before, looking for such evidence can be supported because doing so stretches the limits of science and technology. Finding actual life would be a bonus.
I am curious if, as Raging Bee suggests in @#38, you are equally agnostic about the existence of other things like fairies. After all, many people claim to have seen them. Do you rule out their existence along with ghosts and vampires and dragons and so on? If so, on what basis?
Mano @39: While not addressed to me, I would love to answer your question.
You’ve presented two options; assuming existence or nonexistence (maybe qualified by ‘provisional’?). My personal categories are a bit more complicated.
Phlogiston and aether are in my ‘nonexistent’ file, with the qualification (subfile, if you like) that they were reasonable suppositions at the time they were made.
Fairies, souls, vampires and deities are in a different file. I call it the ‘Not worthy of consideration’ file. AKA the ‘No compelling evidence to take seriously’ file. That doesn’t mean ‘nonexistent’. It means not worth worrying about existence or nonexistence.
I have many files. Restricting the effective number to two seems really odd to me.
@39
What we do know however is that life was *very* quick to start on this one. It seems implausible that it exists on Mercury, Venus, or Mars. I’d guess Venus is the slightly less implausible candidate there. Further out we really haven’t ruled much out so we’re really in the realm of not knowing there.
But here? It seemed to sprout basically as soon as it physically could do. No hanging around for a billion years or so until the right throw of the dice happened. Now if life is unlikely, scarce, you really do have a problem about that… kind of the German Tank problem. If you see a German Tank cresting the hill with number N written on the side, what is the likely number of German Tanks in total? If life took several billion year to start, then maybe it’s scarce. If it took only millions of years after the Hades environment then you really have a hard problem of saying why that wouldn’t happen anywhere else.
So, we know there are a *lot* of planets out there. It’s just completely unreasonable to assume the few we’ve detected are the only ones, or anything other than the tip of the iceberg.
It’s also unreasonable to assume that a bunch of them won’t fit into the same physical niche as Earth: right energy-input range, right chemical composition, to be able to support a range of surface conditions similar to ours. (I mean, life-like systems could well exist outside of that niche, but that is definitely in the realm of supposition, but we do know what we do know.)
Our scale of intelligence is a matter for conjecture since we have one sample among billions there. But life? If you’re equating that with the existence of vampires or fairies I think you’ve seriously misconstrued both the evidence and logic surrounding our own existence.
In my book I discuss one other thing and that is that in science we sometimes assign provisional existence to an entity even if we do not have a preponderance of evidence for its existence as long as that entity is a necessary explanatory concept in the dominant paradigm.
So for example, the neutrino was granted provisional existence status for about 25 years even though it had not been directly detected because the alternative explanation was that energy conservation was violated in some nuclear reactions. Those who denied the existence of the neutrino argued that the universal claim of energy conservation in all reactions was violated by those particular reactions. So given the choice between an existence claim for the neutrino and a violation of a universal claim of energy conservation, the majoirity of scientists tended to give the neutrino provisional existence status until its direct detection shifted it into an existence claim for which there was a preponderance of evidence. The story of the Higgs is a similar one, where it was a necessary explanatory concept in the standard model and hence given provisional existence status until it was confirmed.
Conversely, the aether was similarly given provisional existence status because it was thought to be a necessary explanatory concept for the propagation of light. The theory of special relativity did not disprove the existence of the aether but it made it no longer a necessary explanatory concept. So in the absence of direct evidence for its existence, it was deemed to not exist. If the search for the Higgs boson had continued to be elusive and a new paradigm came along for which it was no longer necessary, then it too would have been deemed to not exist.
ETs, fairies, ghosts vampires, etc. have neither any evidence in support of their existence nor are they necessary explanatory concepts. Hence we can dispense with them without causing any problems.
xohjoh2n @#41 makes a plausibility argument. But plausibility is in the mind of the beholder. The advocates of intelligence design also make a plausibility argument for their designer, pointing to things that they say science has not been as yet able to explain and saying that the complexity of life makes it hard to imagine that such a designer does not exist. How would you argue against their plausibility argument while defending your own? After all, there will always be new aspects of life that come along that science has not been able to explain, just like there will always be new UAPs.
The decision rules for existence and universal claims are powerful tools in science and in everyday life. We cannot pick and choose to apply them only when they suit our own preferences.
Rob @40,
One can sort things into as many files as one likes. The question is whether there is any basis for deciding what goes where other than personal preference.
@Mano
Whats the % ?
No not equally. There is a higher degree of confidence because we have looked more and not found anything. But I should note its a matter of trust rather than evidence. Have I personally looked -- No . Have I personally verified -No. Could we really know if they existed sometime long ago in the past -- No.
But why fairies -- Do you know all the species that have existed ? we have evidence for some of them -- but by your logic nothing else has existed!
I dont see why these questions are treated as a boolean True:False. And I dont see the benefit of doing that either.
Deepak:
Because something either does exist or it does not exist.
Do you rule out [fairies’] existence along with ghosts and vampires and dragons and so on? If so, on what basis?
Two reasons: first, they’re supernatural and violate physical and biological laws that we know are in effect everywhere we look. And second, the specific claims about those creatures’ existence is that they exist(ed) HERE ON EARTH — and in all the time we’ve been here on Earth we’ve never seen any evidence of their existence in any of the places they’re said to have existed.
Sometime in the future we might find evidence that, say, fairies, or creatures very much like the fairies of our folklore, exist on some other planet. But such a discovery would not support any claims about fairies on Earth — unless some link was discovered, like that species originated on one planet and migrated to the other.
@John Morales
Except a feline’s life status in a closed box …
But in any case we are talking about the degree of certainty of the outcome , not the outcome.itself.
Deepak:
The topic at hand is existence claims.
An existence claim is not a degree of certainty, it is a definitive claim.
But sure, one could approach that using a tertiary logic, such as [T|F|U].
Trouble with that approach is that |U| >> |T| ∨ |F|.
[Um, ternary]
@ 48 John Morales
Apparently, the point went over your head at approximately the cruising altitude of a 737. Allow me to help:
https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s_cat
(sigh)
No, BobTheSilent, I got the reference. It merited no response.
Your sniping is becoming tiresome, and you do yourself no favours thereby.
Anyway. Schrödinger’s cat was intended to be akin to a reductio ad absurdum of trying to describe the concept of superposition in ordinary terms, not a demiexistential claim. Duh.
—
So, did you note how my #45 & #48 basically reiterate the major point of Mano’s #21?
(Care to dispute any of it?)
Silentbob @50: Don’t know who wrote that wikipedia article, but it’s crap.
There is no interpretation which sees the cat as in a superposition of dead/alive states. The ‘measurement’ is made before the cat knows anything about it, and certainly before the box is opened. Anyway, Ethan Siegel has a good rundown;
https://www.forbes.com/sites/startswithabang/2020/06/26/ask-ethan-what-are-we-getting-wrong-about-schrodingers-cat/?sh=39160bc2dd9b
I do believe that UFOs/UAPs exist, the reason being that the U is for “Unidentified” and the people who have actually seen them were just unable to identify what they were seeing.
John Morales, #9:
Nonetheless,“likely is” is a factual claim: you’re claim that there is (as a matter of fact) X likelihood of a statement being true or false. So, of course you still need decent reasoning and evidential support for that claim. It’s not as if this somehow means the claims are any easier to make, that you can just do this on a whim or as an expression of “personal preference,” or that they don’t require the same kind of evidence or reasoning to support them which we ought to demand of factual claims in general.
For the case of Russell’s teapot, we have some very solid reasons to believe that there is no such teapot, although I won’t go through all of that here.
For claims about aliens visiting Earth, whether they involve UFOs or abductions or what have you, we also have good evidence that such things very likely have not happened.
However, when the question is instead about the existence of any alien life elsewhere in the universe (not from Earth), we’re dealing with a substantially different set of relevant evidence because the question is so much broader in scope, and it looks like the evidence supports the claim that there probably is at least some life like that somewhere else (although for various possible reasons, it’s not visiting Earth, probably).
When it comes to fairies or vampires or what have you (including Russell’s teapot), it’s really dumb to ignore an important piece of evidence which is very well established: those are all fictional entities. So, for instance, although it’s maybe not “a work of fiction” in the everyday sense, Russell simply came up with that hypothetical teapot in order to make a point, knowing perfectly well that he was constructing or inventing the concept of it to suit that particular purpose and that it definitely isn’t a real thing.
That’s not the sort of thing we’re dealing with in the case of extraterrestrial life. Even if you think that what we’ve got to support the claim isn’t entirely satisfactory (never mind conclusive, much less a logical proof), what you don’t have is conclusive evidence against it, to the effect that we know it’s false because we know people deliberately crafted it as a fictional thing to tell a story (maybe one with interesting characters, one which is meant to teach a lesson, etc.) or something along those lines. So it’s just plain silly to put all of it on the same footing, as if extraterrestrial life had anything approaching that in terms of very compelling evidence against its existence. In other words, even if the positives may be a bit small in your estimation, there isn’t a huge negative like that which is certainly going to outweigh them.
Raging Bee, #13:
What’s so vague about it? There either is life on another planet or there’s not. It may be quite different from life here, but nobody has any trouble with the purported “vagueness” of the claim that life exists on Earth, even though there is of course still some room for debate about how to carefully define the term “life” or what we ought to mean by it (given the ways that we intend to use it).
Also, although it would be wildly impractical to do so, definitely not something humans can actually do, one could (in principle) disprove that by checking every existing planet and moon so forth. Obviously. Yes, also obviously, there are too many which are too far away, so in fact we’ll never do that. But the standard you’re appealing to is normally understood to cast aside claims that can’t in principle be supported by sufficent evidence, not just stuff that we happen to be incapable of doing (as of this moment or perhaps ever).
What’s so vague about it? There either is life on another planet or there’s not.
What’s vague about your claim, as you worded it, was the location. Or rather, the failure to specify a location other than “somewhere other than Earth.” That means that in order to prove or disprove the claim, you’d have to scour the entire universe — something no civilization, however advanced, is likely to ever be able to do. Even if you narrowed such a claim down to “there is life on a planet with particular properties,” you’d still have to scour the universe looking for all planets of that type before you could consider the claim disproven. In theory the claim is falsifiable, in practice it’s not.