At most we should ascribe a prior probability of zero and then do some Bayesian updating to get a posterior.
I think you'd have to call that "Bayesian not-updating". If your priors include 0 or 1 those beliefs will not change through Bayesian updating.
The prior is P(A), which we have said is 0. The posterior is P(A|B), which happens to be a fraction with 0 as the numerator!
Prior to watching the video, I have a very low estimate of the probability of aliens on earth (intelligent aliens visiting within human history, p ≈ 0.0001, intelligent aliens sending probes of any kind to earth during human history, similar, anything of alien origin coming to Earth over it's entire history: p ≈ 0.1, though I could easily be persuaded of a higher or lower estimate).
We'll see what effect the video has on those estimates.
--After watching the first half hour, taking comments in a window to the side throughout--
"Halt and his team locate three indentations [dramatic pause] in the shape of a triangle" in a very authoritative voice.
"Over two days, 60 personnel reported that they had seen a UFO." How were they asked?
They really like triangles. "my wife and I saw three bright white lights [dramatic pause] in triangle formation". Triangle formation, as oppposed to a line? Either way, it would have sounded significant and ominous.
The original investigation is missing any confirmatory evidence--but that also means it lacks any disconfirmatory evidence. This is exactly what you would expect to see in unexplained cases if there actually was nothing ...
can thousands of them be 100% erroneous
In short, yes. In a country of hundreds of millions of people, finding thousands of people with any shared characteristic is not surprising. As faul_sname said, I would expect at least hundreds of thousands of people to be eyewitnesses to anything happening over a major city.
Independently, our current knowledge of physics strongly suggests that interstellar travelers arriving in this solar system would be visible (during deceleration) to any serious observation of the night sky, whether Mayan, Ptolemaic, Galilean, or modern. The absence of any record that suggests arrival is strong evidence against interstellar aliens.
Many of your points are not primary evidence though.
Primary evidence includes eyewitnesses. And even if it didn't, the secondary evidence is so strong that total absence of relevant primary evidence is irrelevant.
You asked elsewhere why you are getting downvotes, and the brief answer is that you are dramatically over-weighing the strength of the relevant evidence.
An unidentified flying object is just that: unidentified. Not "identified as alien". The argument is isomorphic to "God in the gaps", for which I think there are few takers here.
I think you may be confused by an oversimplification of Occam's Razor: "Extraordinary claims require extraordinary evidence." That's not actually how you derive a prior - the very word "extraordinary" implies that you already have experience about what is ordinary and what isn't. If we really throw out all evidence that could tell us how likely aliens are, we end up with a probability which (by the usual method of generating priors), depends on the information-theoretic complexity of the statement "There are aliens on earth."...
Watched the first 15 minutes, didn't seem super convincing, so I stopped - have to put bread in the oven soon. Anyhow, it's really easy to just make shit up on television - by which I don't (just) mean lying, making things up is just a natural consequence of rationality failure. The unreliability of eyewitness testimony and all that. The only things in the first 15 minutes that weren't eyewitness were the picture and the geiger counter reading. If you go back and look at the picture, it's a shitty non-equilateral triangle made out of two things that loo...
Anyhow, it's really easy to just make shit up on television. The unreliability of eyewitness testimony and all that.
It's especially easy to do so on TV. Anyone interested should check out this video. I have a high prior that the documentaries that the OP links to use the same sort of tricks described therein.
Another question arising in this matter is how to treat evidence of extraordinary things. Should one require 'extraordinary evidence for extraordinary claims'? I somehow feel that this notion is misguided - it discriminates evidence prior to observation. That is not the right time to start discriminating. At most we should ascribe a prior probability of zero and then do some Bayesian updating to get a posterior.
As ParagonProtege noted below, if your prior is 0, then your posterior is also zero no matter how compelling the evidence you observe. As I unde...
Another question arising in this matter is how to treat evidence of extraordinary things.
Dealing with extraordinary claims has not gotten the attention it deserves, IMO.
It gets to the distinction between an explanation, and a predictive model. Explanations assuage mental anxiety over the unknown. Predictive models, in general, allow you to do something. If, in some particular case, the predictive model associated with an explanation doesn't allow me to do something, it is not a useful model.
Let's assume some advanced alien intelligence is patrolling t...
Should one require 'extraordinary evidence for extraordinary claims'? I somehow feel that this notion is misguided
Extraordinary just means low probability. So if some claim is extraordinary (in this case, aliens) then it has a low probability. Similarly, you would need extraordinary evidence to update the prior to the "ordinary" range. If you look at the simple version of Bayes Theorem, it is P(H | E) = P(E | H)P(H) / P(E). If both P(E) and P(H) are low (i.e. extraordinary) then they will sort of cancel each other out and P(H | E) will be clos...
An idea with more acceptance on this board is that we are more likely in a simulation than in the real world. This is more accepted at least in the sense that posts that support this hypothesis are not vote-bombed down.
An interesting thing to ponder is that in a simulated world we would be very likely to have what would be essentially aliens among us. The intelligences running the simulation would have not particular reason not to intervene in the simulation when and how they felt like it in ways that violated the physics of the simulation. These inte...
What about this: A piece of shrapnel, found at the Roswell crash site, that doesn't have the isotopic composition that earthly metals has:
" Kimbler says the isotope work is so important because the ratios are “very much like our fingerprints.” Certain concentrations of elements on earth are unique to Earth. So if you know isotopic ratios for magnesium, it will be the same for anything on earth with magnesium, but if it is not from Earth, it will have a different ratio. For instance meteorites have different ratios because they are not from Earth. Isot...
Isotopic analysis is necessary to determine if a material is from Earth or another world." http://www.openminds.tv/test-confirms-roswell-debris-733/
...really? Here is the data they found.
Isotope | Measured | Background
--------+----------+------------
Mg-24: | 79.1±0.5 | 78.6
Mg-25: | 10.1±0.5 | 10.1
Mg-26: | 10.8±0.5 | 11.3
You will note that the natural background concentrations fall within the error bars of the measurements. Meaning no significant difference.
When you plot it on a graph with no error bars, it looks like the measurement is really anomalous. When you notice that the error bars are as large as they are and the measurement errors are in opposite directions, it becomes quite obvious why that measurement falls so far from the line he plotted. Consider that the error bars are 0.5% in either direction, and the graph is only 1% on a side. That means you would expect a measurement of a sample from Earth to fall... somewhere on the graph. Not any more specific than that though.
It is things like this that make us skeptical of supernatural claims. If the aluminum compound actually came from space, we would expect a much higher concentration of ...
Maybe this talk by Stanton Friedman will be of more interest to this audience, than a history channel documentary: http://www.youtube.com/watch?v=uOAvL1O3DyM
I might watch it later. (I'm not reading the other comments yet because I don't want to be primed.)
I have gotten 6 private messages as reply to this post (that has also been posted in this thread). Previously I've experienced the same. Why don't people just post in this thread only? Is it a culture thing?
Due to low karma i can't reply in the relevant comment thread, so I do it here:
Desrtopa wrote:
If you think there's an inconsistency in people's dismissal of UFO eyewitness accounts, I think you may not have grasped the principles of Bayesian reasoning yet.
Baysian reasoning says to treat all evidence equal. The prior may be low, say 0.01, but that's all. There is no weight of the prior that can change. Thus if we see new evidence the update of the probability isn't affected by some magic weight that could diminuize the size of the update arbitrarily muc...
This thread has mostly taken the form of "LessWrong tells loldrup why he is wrong," which has the unfortunate side effeect of making it very difficult to admit you are wrong, even if you later encounter evidence that you would have otherwise considered convincing.
What would you consider good evidence that there are no aliens on Earth?
So here are descriptions of some more scientific studies, conducted by the US and the French military:
http://en.wikipedia.org/wiki/Project_Blue_Book#Project_Blue_Book_Special_Report_No._14
It's interesting how the conclusion in the US report is at odds with their own data. If you read the section please read it thoroughly to get the details.
Okay I'm simply going to put (part of) the section out here (hope its okay). I have emphasized some places:
"In late December 1951, Ruppelt met with members of the Battelle Memorial Institute, a think tank based in...
Just curious: why did the comment quoted below get down voted? While it may be a bit a bit colorful it raises an issue that is relevant in this case: do we discriminate between evidence a priori?
"Also, remember to apply even standards to evidence. If you flat out deny ufo eye witness accounts as being without epistemic value, also do this for all other eye witness accounts:
Your girlfriend says she saw an eagle over the creek? Didn't happen. And don't investigate any further.
Your friends talk about the beautiful yacht that left the harbor this morning?...
If aliens are on earth their behavior is indistinguishable from no aliens being on earth. If I flip the switch in my head from believing that aliens are on earth to aliens not being on earth, what will I do differently?
Ascribing a prior probability of zero for these claims is like saying we should ignore all previous evidence and start over from scratch. But this is inappropriate; there is a long history of "aliens on Earth"-type claims that have been made over the years, and they've all been shown to be insufficient. So when a new "aliens on Earth"-type claim arises (like your linked video, which I have not yet clicked on), it is entirely appropriate to assign it a low prior.
also take a look at this:
http://www.youtube.com/watch?v=Hh1jDZoj2xs
It describes a case where a village sustains a long period of attacks by hot columns of light emerging from objects in the sky. The village is panicked and the military dives in and make a lengthy report.
Here's an observation database: http://www.ufostalker.com/
go see what's near your location.
I find these particularly scary (I have only looked at a few of the cases): http://www.ufostalker.com/ufostalker/UFO+Sighting+in+Greenville+Ohio+United+States+on+November+18th+1967/43826 http://www.ufostalker.com/ufostalker/UFO+Sighting+in+denmark+Denmark+on+July+4th+2000/29937
Recently I've been struck with a belief in Aliens being present on this Earth. It happened after I watched this documenary (and subsequently several others). My feeling of belief is not particular interesting in itself - I could be lunatic or otherwise psychological dysfunctional. What I'm interested in knowing is to what extend other people, who consider themselves rationalists, feel belief in the existence of aliens on this earth, after watching this documentary. Is anyone willing to try and watch it and then report back?
Another question arising in this matter is how to treat evidence of extraordinary things. Should one require 'extraordinary evidence for extraordinary claims'? I somehow feel that this notion is misguided - it discriminates evidence prior to observation. That is not the right time to start discriminating. At most we should ascribe a prior probability of zero and then do some Bayesian updating to get a posterior. Hmm, if no one has seen a black swan and some bayesian thinking person then sees a black swan a) in the distance or b) up front, what will his a posterior probability of the existence of black swans then be?