# Basis of science's belief that extraterrestrial life is likely? **URL:** \ **Category:** Great Debates\ **Created:** [November 10, 2010, 3:43am UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137 "2010-11-10T03:43:11Z")\ **Posts on this page:** 20\ **Page:** 8
**Author:** ![Diogenes\_the\_Cynic](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@Diogenes\_the\_Cynic](https://boards.straightdope.com/u/Diogenes_the_Cynic)\ **Post date:** [November 10, 2010, 6:03pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/141 "2010-11-10T18:03:42Z")
It’s not a given that it happened just once on earth. There could have been false starts, or competing pre-biotic activity that got wiped out once a good biotic fire got going. ---
**Author:** ![Diogenes\_the\_Cynic](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@Diogenes\_the\_Cynic](https://boards.straightdope.com/u/Diogenes_the_Cynic)\ **Post date:** [November 10, 2010, 6:05pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/142 "2010-11-10T18:05:12Z")
> [@Xema](#): > > Blake’s point about intelligent life relates to the anthropic principle. I still can’t see what the anthropic principle has to do with the question of whether there are likely to be microbes on other planets. ---
**Author:** ![Acid\_Lamp](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@Acid\_Lamp](https://boards.straightdope.com/u/Acid_Lamp)\ **Post date:** [November 10, 2010, 6:05pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/143 "2010-11-10T18:05:45Z")
> [@Xema](#): > > Yet it seems to be widely accepted that it happened just once on Earth, which can be taken as evidence that it’s highly unlikely even here. Fair point, but that falls squarely into the category of, “we may never know”. My understanding is that once started, life has never been completely extinguished on our planet, despite plenty of radical changes in environmental conditions. Something always held on and took over again. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 10, 2010, 6:08pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/144 "2010-11-10T18:08:27Z")
> [@Acid\_Lamp](#): > > Even if we assume that only 1 in ten is suitable, and then assume that only one in hundred of those has actual earth like conditions, and then assume 1/100 of THOSE has condition after condition… If there were a way to verify - even within wide limits - the accuracy of these assumptions, the conclusion might have some real value. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [November 10, 2010, 6:15pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/145 "2010-11-10T18:15:01Z")
> [@Acid\_Lamp](#): > > My understanding is that once started, life has never been completely extinguished on our planet, despite plenty of radical changes in environmental conditions. Something always held on and took over again. A couple of possible ways to explain this: 1. This is an inherent property of life wherever it exists. 2. This is a ridiculously improbable thing that just happened to take place here, eventually resulting in a species capable of considering such matters. Note that if #2 is the case, that species is likely to be fooled into thinking that their improbable situation is typical. ---
**Author:** ![Acid\_Lamp](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@Acid\_Lamp](https://boards.straightdope.com/u/Acid_Lamp)\ **Post date:** [November 10, 2010, 6:21pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/146 "2010-11-10T18:21:31Z")
> [@Xema](#): > > A couple of possible ways to explain this: > > 1. This is an inherent property of life wherever it exists. > 2. This is a ridiculously improbable thing that just happened to take place here, eventually resulting in a species capable of considering such matters. > > Note that if #2 is the case, that species is likely to be fooled into thinking that their improbable situation is typical. Both of which ought to produce a positive stance on the existence of life elsewhere. If 1, then it should be common throughout the universe. If 2, then it would be rare, but still bound to happen occasionally given the nearly unimaginably large scale of the universe. I could see a stance like: " The chances of life elsewhere is most likely very remote, and the chances of us discovering it are even smaller, so for all intents and purposes it should be considered that we are alone until we can revise our position by investigating in person." ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 10, 2010, 6:30pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/147 "2010-11-10T18:30:51Z")
> [@Blake](#): > > No, you haven’t. You’ve just handwaved about viruses (which are non-living but require complex, pre-existing cellular machinery to reproduce)and undefined self-replicating molecules. > > For you argument to be even semi-plausible you need to tell use where this occurred? On Earth? Another planet? Benthic Oceans? Palagic Oceans Atmosphere? What were the precursors and how did they arise? What was the original self-replicator, and how did it obtain raw materials? We know it happened here, and we are wondering about another planet. Why don’t you tell me where you think the low probability event is? Is it the existence of oceans on a new planet? Is it the warmth of these oceans? Is it the availability of various carbon based molecules in these oceans floating around? Is it the proclivity of some of these molecules to combine? Is it the existence of at least one self-replicating molecule that might be formed, over time, from some of these? (I trust you are not arguing that the breath of God is required to create a self-replicating molecule.) Is it that random changes to the molecule, through imperfect replication, could cause more efficient and complex ones to evolve (and I use that term to mean descent with modification.) Is it the transformation of this molecule into something we call living - which seems ill-defined. The only thing here that seems the slightest bit improbable is the first self-replicating molecule - but we have tens or hundreds of millions of years and lots and lots of chances in which this can happen. Most of the hypotheses I’ve seen are of places where this process would be faster. > [@](#): > > When you have answered those very basic questions, with evidence, then you argument will be semi-plausible. At the moment it’s not an argument at all. I’ve read the actual journal articles on this stuff. Your argument has no legs whatsoever because it fails to address the most obvious problems such theories need to address. > > And you are wrong. We have no idea how life arose. Even the authors in the premier journal sin the field all admit that. As I said, no one is going to publish something claiming they know the answer. We are trained to be way too tentative for that. But are you saying that there are no articles stating that life is not improbable? There have been plenty of articles offering hypotheses about how it could have happened - I remember clay and hot water vents. There have been some people saying life is improbable. One says that a large moon causing tides is necessary, and that this is rare (we don’t know this for sure.) It seems this comes from a religious conviction that we are specially created (or our precursors are) and is not mainstream. But this person at least tried to justify why he said life is improbable, which is more than you’ve done. ---
**Author:** ![silk1976](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@silk1976](https://boards.straightdope.com/u/silk1976)\ **Post date:** [November 10, 2010, 6:53pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/148 "2010-11-10T18:53:51Z")
> [@Blake](#): > > Cite! > > Since you claim that this is based on probability, you will be able to show us the probability equations used and the resulting probability, yes? > > I am eager to see these, especially the part that determines in the probability of life arising on an Earth-like planet. Surely, you can’t be serious. Many times, Blake, you seem to be obstinant for the sake of being obstinant. I understand your desire to see people provide some basis for what they are saying, but it seems like sometimes the trees block your view of the forest. You want a cite for what I said? [Fine.](http://books.google.com/books?id=0co_UQgNXacC&pg=PA229&lpg=PA229&dq=probability+of+life+in+the+universe+neil+degrass+tyson&source=bl&ots=pKOIl4tX52&sig=QE4t2faVCQKCyNyPu6uu2VdamdM&hl=en&ei=R-naTPSsF4SKlwf7hIj_CA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBUQ6AEwAA#v=onepage&q&f=false) As I said, the OP asked why SCIENCE - not you or anyone else - has reason to believe why there is probably life elsewhere in the universe. You wanted to trust in what scientists said regarding a mammal jumping no more than 1 meter high unaided, now I ask you to simply trust your eyes and read what a prominent astrophysicist has to say on the matter. Please don’t confuse what he is saying as absolute proof. Noone knows for sure whether there is life or not. Tyson could be wrong, he could be right. He is simply laying out the reasons why he believes what he believes. This thread has already devolved into one where people are looking for proof - but that is not what the OP was about. ---
**Author:** ![silk1976](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@silk1976](https://boards.straightdope.com/u/silk1976)\ **Post date:** [November 10, 2010, 6:57pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/149 "2010-11-10T18:57:16Z")
> [@Diogenes\_the\_Cynic](#): > > Science does not make a claim that life definitely exists elsewhere, only that it’s unlikely - given the size of the universe and the ubiquity of the conditions and bulding blocks that led to abiogenesis on earth - that earth has somehow been uniquely special and magic in its ability to produce replicating molecules. Eh? See my post above, with a link to a passage from a popular and well known astrophysicist, who claims that most astrophysicists agree that that chances are life is elsewhere in the universe. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 10, 2010, 7:00pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/150 "2010-11-10T19:00:10Z")
> [@Acid\_Lamp](#): > > Fair point, but that falls squarely into the category of, “we may never know”. My understanding is that once started, life has never been completely extinguished on our planet, despite plenty of radical changes in environmental conditions. Something always held on and took over again. We have no way of knowing this. There might have been locally established life which got extinguished by a catastrophe. There might have been several variants, perhaps arising from different initial replicators, and our variant out-competed the other one. At this stage it is unlikely we will ever get exact evidence. However, we don’t know who invented the wheel, and never will, but it did get invented - and more than once but not always. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [November 10, 2010, 7:09pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/151 "2010-11-10T19:09:58Z")
If we discovered life on Mars, or Europa, or Alpha Centauri 6, and determined that life was the result of an independent abiogenesis, that would definitely be strong evidence that life is likely on lots of other planets. But our observation of life on Earth isn’t. The reason Blake is going on and on about the Anthropic principle, is that we humans observe life on Earth. But if there was no life on Earth, there wouldn’t be humans to observe the lack of life, just like there are no intelligent species on the Moon observing that the Moon lacks life. So therefore, any species that observes life on its own planet must have evolved on a planet where life evolved. This is a subtle point. But it means that our sample is biased. We know there are plenty of planets without life, we can observe dozens of them in our solar system. Suppose for the sake of argument that there is only one planet in the entire universe that has life. And on that planet intelligent life appears. They observe that their planet has life. What can they conclude about the likelihood of life evolving on other planets? Nothing–because if life hadn’t evolved on their planet, they wouldn’t be able to observe the life on their planet. However, if they observe a second instance of life, and that instance of life arose independently, then they have an independent instance of life. And NOW they can do some back of the envelope calculations. Of course, it could be that life really is fantastically rare, and they just hit the jackpot. But that sample isn’t biased by the fact that it had to exist before the observation could be made. So, if tomorrow we discover another planet with liquid water, and that planet has life, suddenly the odds of life arising on a suitable planet can be estimated at somewhere near 1. Our estimate could be way off, but now we have some reason to trust that we don’t have an unbiased sample, and since we pulled out a red jellybean we have some justification for betting that the next jellybean we pull out might be red. And if we pull out two red jellybeans, then our confidence increases. And if every time we pull out a jellybean (a planet with liquid water) that jellybean is red (has life), then we can put very clear numbers on our confidence in the outcome of the next sample. But we should throw out the sample that generated the observer of the experiment, because we know that sample HAD to generate the observer, because otherwise there would have been no experiment. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 10, 2010, 7:22pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/152 "2010-11-10T19:22:56Z")
> [@Blake](#): > > Let’s say this is true, how does it change the fact that there is or is not a scientific > basis from which we can produce an answer? Would the answer be more scientific if it was less scary, or more? If by answer, you mean an exact probability or a yes/no answer, sure, and no one is pretending otherwise. But there is certainly a scientific basis to state that it seems there are no barriers to life arising elsewhere. > [@](#): > > No, we don’t. Once again, false dichotomy. We can declare that we have insufficient evidence and not “go” with anything until we get more evidence, no? We don’t have sufficient evidence to identify the self-replicating molecule that was the precursor of RNA. We have plenty of evidence to understand that life or proto-life can exist in a very simple form, simple enough to have arisen naturally. You mentioned that viruses today are specialized. Of course they are - they are the result of almost a billion years of evolution, and they mutate rapidly. The fact that we can construct working viruses for smaller pieces does indicate that nature can too, given enough time. The virus would only be successful if it could grab organic molecules or other viruses, of course. > [@](#): > > No. Absolutely not. Science can only tell us what is. It can never, ever, ever tell us what should be. But it can tell us what might be. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 10, 2010, 7:48pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/153 "2010-11-10T19:48:43Z")
> [@Acid\_Lamp](#): > > No, I’m saying that when asked for answer that cannot be conclusively given, we should say so, but not be afraid to speculate either when pressed to guess. The speculation, the hypothesizing is what drives the whole process. If you refuse to even hazard a guess, why should anyone place confidence, trust or money in your research? Wha…? I give the money to the guy who _does_ refuse to “hazard a guess.” I give the money to the guy who speculates only _when there is a basis_ for speculation. Speculation without a basis is \*anti-\*scientific. What Blake is saying is there is no basis for speculation. One may disagree with him about that, but let’s all please be sure we understand what he’s actually _saying_. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 10, 2010, 7:50pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/154 "2010-11-10T19:50:57Z")
> [@Acid\_Lamp](#): > > Answered above. Don’t be ridiculous. Not everything is a binary statement. > > There is nothing wrong with stating: “We can’t be certain because of a number of factors, but I believe the available evidence supports or refutes the existence of extraterrestrial life”. Blake said he doesn’t believe the available evidence _either_ supports _or_ refutes the existence of terrestrial life. You responded to him by saying that he should take a position anyway. You said he should take a position on an issue which he believes does not yield evidence sufficient for taking a position. To take a position in such a circumstance is dishonest. You advocated dishonesty, then, whether you meant to or not. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [November 10, 2010, 8:03pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/155 "2010-11-10T20:03:32Z")
One more comment on the “life arose fast” issue. It seems to me that life on Earth undergoes various catastrophes and it’s perfectly plausible that any of these catastrophes could have wiped out early protolife before it could evolve into full life. However, I don’t see why this means that protolife therefore has only one shot at evolving into life, and if it misses that one shot the planet will remain lifeless forever. It seems to me that if we’ve got protolife sitting around, and an asteroid strike sterilizes the planet, the chemical precursors of that protolife are still going to be around. There will still be water, there will be carbon, there will be nitrogen, and so on. And as the planet recovers, we’re back where we started when the planet formed, and protolife starts to organize again, and we have a chance for that protolife to become life again. Now, it’s easy to imagine catastrophes that could really permanently bollix a planet–for instance it seems that all the crust of Venus is only a few hundred million years old, which could be due to the whole planet’s crust becoming liquid magma at one point. That could drive off all the volatiles needed for protolife, and the planet is permanently unsuitable for life. On the other hand, this would have exterminated full life anyway. I guess I have a hard time imagining a catastrophe that would be survivable by true life, but which would destroy all protolife and the chemical precursors like water and methane that would be the building blocks of protolife. Even if there’s a catastrophe that destroys life, why does that permanently render the planet incapable of forming protolife again? So, the impact that formed the Moon would have liquefied the crust of the Earth. Therefore, life on Earth would have to form after that impact. But that doesn’t mean there was no life on Earth before the impact–just that that life/protolife would have went extinct and all traces of that life would be destroyed. ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [November 10, 2010, 8:17pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/156 "2010-11-10T20:17:00Z")
> [@Lemur866](#): > > If we discovered life on Mars, or Europa, or Alpha Centauri 6, and determined that life was the result of an independent abiogenesis, that would definitely be strong evidence that life is likely on lots of other planets. But our observation of life on Earth isn’t. > > The reason Blake is going on and on about the Anthropic principle, is that we humans observe life on Earth. But if there was no life on Earth, there wouldn’t be humans to observe the lack of life, just like there are no intelligent species on the Moon observing that the Moon lacks life. > > So therefore, any species that observes life on its own planet must have evolved on a planet where life evolved. This is a subtle point. But it means that our sample is biased. We know there are plenty of planets without life, we can observe dozens of them in our solar system. True, but for a very long time there was life on earth with no one to observe it. In fact we know that at some point there was life, but not intelligent life, in the universe. > [@](#): > > Suppose for the sake of argument that there is only one planet in the entire universe that has life. And on that planet intelligent life appears. They observe that their planet has life. What can they conclude about the likelihood of life evolving on other planets? Nothing–because if life hadn’t evolved on their planet, they wouldn’t be able to observe the life on their planet. You are neglecting some very important evidence. Say that on this planet the least complex form of life (counting viruses) is a single celled creature, and thus quite complex. Say they can’t find evidence of anything in the past that is significantly less complex than this. Assuming that they haven’t caught the religion bug, they might be excused in saying that life is inherently complex from the outset and thus very rare. If they find another planet with simple life forms, this hypothesis would be falsified. We on the other hand know that life can be quite simple, and are thus able to estimate the probability of life elsewhere as much higher then they can. ---
**Author:** ![Acid\_Lamp](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@Acid\_Lamp](https://boards.straightdope.com/u/Acid_Lamp)\ **Post date:** [November 10, 2010, 10:12pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/157 "2010-11-10T22:12:25Z")
> [@Frylock](#): > > Blake said he doesn’t believe the available evidence _either_ supports _or_ refutes the existence of terrestrial life. > > You responded to him by saying that he should take a position anyway. You said he should take a position on an issue which he believes does not yield evidence sufficient for taking a position. > > To take a position in such a circumstance is dishonest. > > You advocated dishonesty, then, whether you meant to or not. Not really. If more evidence were available to be reviewed, or likely to be revealed within a reasonable time frame then perhaps. Since it is unlikely that we will get much more in the way of hard numerical type evidence any time soon, we either have to use what we DO know, or scrap the whole thing. The problem with ignoring the question is that: 1. It isn’t going to go away any time soon. 2. It has a lot of bearing on how we pursue our space program. 3. Refusing to even _make a guess_ makes you look incompetent, weak, and unwilling to be open to debate. At worst it makes you look arrogant, and uncooperative; science as a whole already has enough bad PR from the religious nutters, and plain sense folks without looking stupid over a niggly logic loop. 4. It encourages even worse types of thinking to provide a response, notably religious and superstitious woo thought. 5. Given the enormity of scale of the question, I don’t think that Anthropic principle is applicable, or at least is being applied overly rigorously in this instance. People look toward science to provide a rational, logical, opinion on questions about our world. Science has the responsibility to the public to provide the facts, but if there is plenty of evidence for a debate, but not enough to seriously settle it then the best _anyone_ can do is make an educated guess. There is nothing ignoble, or disgraceful about having an incorrect hypothesis that must be resolved when new facts appear. Likewise there is nothing silly or risky about engaging in educated speculation to keep the debate on firm footing and provide some framework to further guide research in areas relevant to the debate. Science fails often and spectacularly, and it should. It is how we KNOW that something is correct. ---
**Author:** ![Superfluous\_Parentheses](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@Superfluous\_Parentheses](https://boards.straightdope.com/u/Superfluous_Parentheses)\ **Post date:** [November 10, 2010, 10:21pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/158 "2010-11-10T22:21:18Z")
> [@Acid\_Lamp](#): > > 1. Given the enormity of scale of the question, I don’t think that Anthropic principle is applicable, or at least is being applied overly rigorously in this instance. I’d go with this. Yes, it’s _possible_ that life is so improbable that the only reason we know of it is the anthropic principle, but that’s the absolute minimum position. Since **Blake** doesn’t seem to espouse any special creation event, I don’t really see where his objections come from. If the chance of biogenesis on an earth-like planet is really is 1/10^very high, then it’s likely we’re on the only planet that has life. However, we know the chance is not zero and it might even be very close to 1. Seems to me to, we might as well assume that life is out there, since even if the chance turns out to be 1/10^(very high - 10) we’d have ~ 10000000000 planets with life on it. ---
**Author:** ![Max\_Torque](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@Max\_Torque](https://boards.straightdope.com/u/Max_Torque)\ **Post date:** [November 10, 2010, 10:31pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/159 "2010-11-10T22:31:56Z")
[This is the Hubble Ultra-Deep Field view](http://apod.nasa.gov/apod/image/0403/hudf_hst_big.jpg). To get the Ultra-Deep Field view, the Hubble telescope was pointed at an apparently empty patch of the universe, and left alone, for three months. That time allowed the Hubble to pick up even the tiniest pinpricks of light from that region. Every dot of light you see in that image is a galaxy. Not a mere star, but a _galaxy_, containing billions of stars like our sun. And once again, this is in an _empty_ patch of space. So. How special are we now? ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [November 10, 2010, 10:34pm UTC](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137/160 "2010-11-10T22:34:17Z")
> [@Acid\_Lamp](#): > > Not really. If more evidence were available to be reviewed, or likely to be revealed within a reasonable time frame then perhaps. Since it is unlikely that we will get much more in the way of hard numerical type evidence any time soon, we either have to use what we DO know, or scrap the whole thing. What Blake is saying is that we don’t _know_ anything that we _can_ use for the purpose of speculating about whether there is life elsewhere. If he’s right about that, then “using what we do know” is not an option, i > [@](#): > > The problem with ignoring the question is that: > > 1. It isn’t going to go away any time soon. So we keep the question in mind. > [@](#): > > 1. It has a lot of bearing on how we pursue our space program. What has bearing on how we pursue our space program is not the fact concerning whether there is extraterrestrial life or not. Rather, what has bearing (relevant to the present discussion) on how we pursue our space program is whether and with what strength certain people believe there is life out there or not. You can manipulate beliefs in two ways: rationally, or irrationally. Rational manipulation of beliefs involves the use of reasoned argumentation as a guide to the truth of things. Blake thinks the correctly reasoned argument leads us to the conclusion that we are in no position to make claims about how probable it is that there is life out there. If Blake is right about that, then since you’re not allowing that his claim can be allowed to be the claim made by the scientific community, it follows (again, _if you think Blake is right about whether we can assign a probability or not_) that you think we should be manipulating beliefs in some _irrational_ way. But irrational manipulation of beliefs is fundamentally dishonest. > [@](#): > > 1. Refusing to even _make a guess_ makes you look incompetent, weak, and unwilling to be open to debate. It makes you look weak and incompetent to people who are not competent to make that judgment. To those competent to make that judgment, it makes you look judicious and scientific. Do we defer to the ones competent to make the judgment, or the ones not so competent? > [@](#): > > At worst it makes you look arrogant, and uncooperative; science as a whole already has enough bad PR from the religious nutters, and plain sense folks without looking stupid over a niggly logic loop. So then your concern is about how Science _looks to others_, not whether the Scientists are _saying things that are true based on sound reasoning._ That’s dishonest. > [@](#): > > People look toward science to provide a rational, logical, opinion on questions about our world. According to Blake, the rational, logical opinion about this matter is that we don’t have a basis on which to assign any probability. Do you agree with him on that or not? > [@](#): > > Science has the responsibility to the public to provide the facts, but if there is plenty of evidence for a debate, but not enough to seriously settle it then the best _anyone_ can do is make an educated guess. There is nothing ignoble, or disgraceful about having an incorrect hypothesis that must be resolved when new facts appear. Likewise there is nothing silly or risky about engaging in educated speculation to keep the debate on firm footing and provide some framework to further guide research in areas relevant to the debate. Blake’s viewpoint provides for just such a framework. In his view, we don’t have a basis on which to assign a probabiltiy, _but we have a good idea what kind of research to do in order to gain such a basis._ [Previous page](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137.md?page=7) [Next page](https://boards.straightdope.com/t/basis-of-sciences-belief-that-extraterrestrial-life-is-likely/560137.md?page=9)