Carl Sagan

The Debunkers

entirelyuseless Politics, Probability, Science , , , , , , , , , , ,

Why are they all blurry?

In a recent article, Michael Shermer says about UFOs:

UFOlogists claim that extraordinary evidence exists in the form of tens of thousands of UFO sightings. But SETI scientist Seth Shostak points out in his book Confessions of an Alien Hunter: A Scientist’s Search for Extraterrestrial Intelligence that this actually argues against UFOs being ETIs, because to date not one of these tens of thousands of sightings has materialized into concrete evidence that UFO sightings equal ETI contact. Lacking physical evidence or sharp and clear photographs and videos, more sightings equals less certainty because with so many unidentified objects purportedly zipping around our airspace we surely should have captured one by now, and we haven’t. And where are all the high-definition photographs and videos captured by passengers on commercial airliners? The aforementioned Navy pilot Ryan Graves told 60 Minutes’ correspondent Bill Whitaker that they had seen UAPs “every day for at least a couple of years.” If true, given that nearly every passenger has a smart phone with a high-definition camera, there should be thousands of unmistakable photographs and videos of these UAPs. To date there is not one. Here, the absence of evidence is evidence of absence.

So you say everything is always vague? There is never any clear evidence?

Richard Carrier accidentally gives the game away when making the same point:

Which leads to the next general principle: notice how real UFO videos (that is, ones that aren’t faked) are always out-of-focus or grainy, fuzzy, or in dim light or infrared or other conditions of extreme ambiguity (you can barely tell even what is being imaged). This is a huge red flag. Exactly as with the errors of human cognition, here we already know we should expect difficulty identifying an object, because we are looking at unclear footage. That “UFOs” always only ever show up in ambiguous footage like this is evidence they are not remarkable. Real alien ships endeavoring to be this visible would have been filmed in much clearer conditions by now. Whereas vehicles able to hide from such filming would never even show up under the conditions of these videos. When you make the conditions so bad you can barely discern obvious things, you have by definition made them so bad you won’t even see less-than-obvious things.

Notice what? “Ones that aren’t faked?” What I notice is that you aren’t actually saying that all UFO reports and videos and so on are vague and unclear. There are plenty of clear ones. You just believe that the clear reports are fake.

Which is fine. You are welcome to believe that. But don’t pretend that all the reports are vague. This drastically reduces the strength of the argument. Your real argument is more or less, “If UFOs were aliens, we would have expected, after all this time, there would be so much evidence that everyone would already have been convinced. But I am not convinced and many people are not convinced. Therefore UFOs must not be aliens.”

Even in its real form, this is not a weak argument. It is actually a pretty good one. It is nonetheless weaker in the case of UFOs than in many other cases where similar arguments are made, because the evidence could easily be reconciled with a situation where the vast majority of UFOs are not aliens, a few or many “clear” cases are hoaxes, and a few clear cases are aliens who typically are attempting to avoid human notice, but who fail or make an exception in a very small number of cases. And in general it is more likely to fail in situations where the phenomena might be very rare, or in situations where something is deliberately hidden (e.g. where there are actual conspiracies.)

The Courage of Robin Hanson

In a sequence of posts beginning around last December, Robin Hanson has been attempting to think carefully about the possibility of UFO’s as aliens. In a pair of posts at the end of March, he first presents a list of facts that would need to be explained under that hypothesis, and then in the next presents his proposal to explain those facts.

In the following post, he makes some comments on fact of having the discussion in the first place:

I’ve noticed that this topic of UFOs makes me feel especially uncomfortable. I look at the many details, and many seem to cry out “there really is something important here.” But I know full well that most people refuse to look at the details, and are quick to denigrate those who do, being confident in getting wide social support when they do.

So I’m forced to choose between my intellectual standards, which say to go where the evidence leads, and my desire for social approval, or at least not extra disapproval. I know which one I’m idealistically supposed to pick, but I also know that I don’t really care as much for picking the things you are supposed to pick as I pretend to myself or others.

We often fantasize about being confronted with a big moral dilemma, so we can prove our morality to ourselves and others. But we should mostly be glad we don’t get what we wish for, as we are often quite wrong about how we would actually act.

This is not merely theoretical. He in fact receives quite a bit of pushback in these posts, some of it rather insulting. For example, in this recent post, someone says in the comments:

When there’s a phenomenon like Bigfoot or the Loch Ness Monster or Alien visitors, believers often point to “all the evidence”. But lots of bad evidence doesn’t equal good evidence! Navy pilots who say they see UFOs “everyday” actually are providing support for the idea that they are misidentifying something mundane. When talking to those who believe in a phenomenon with low plausibility, the best way to start is by saying, “Lets discuss the *single best piece of evidence you have* and then consider other pieces separately.”

I have seen UFO’s twice and each time my brow was furrowed in a vain attempt to understand what I had just witnessed. If I hadn’t simply been lucky enough to see the illusion again from another perspective, each time I would have walked away convinced that I had seen a large, extremely fast craft far away and not a small, slow object quite close to me. And I’m not easy to fool, as I already understand how perspective can be deceiving.

…

I get the idea that your skeptic skills may be under-exercised compared to the rest of your intellect. I’d recommend reading the Shermer book, “Why People Believe Weird Things” or Sagan’s “The Demon Haunted World.” Both are fun reads.

(5ive)

Robin replies,

Your response style, lecturing me about basics, illustrates my status point. People feel free to treat anyone who isn’t on board with full-skeptical like children in need of a lecture.

The debunkers, who are very often the same few people (note that 5ive refers to a book by Michael Shermer), tend to batch together a wide variety of topics (e.g. “Bigfoot or the Loch Ness Monster or Alien visitors”) as “bunk.” You could describe what these things have in common in various ways, but one of the most evident ways is what makes them count as bunk: There is “lots of bad evidence.” That is, as we noted above about UFOs, there is enough evidence to convince some people, but not enough to convince everyone, and the debunkers suppose this situation is just not believable; if the thing were real, they say, everyone would already know.

As I said, this is a pretty good argument, and this generally holds for the sorts of things the debunkers oppose. But this argument can also easily fail, as it did in the case of the meteorites. While people might accept this as a general remark, it nonetheless takes a great deal of courage to suggest that some particular case might be such a case, since as Robin notes, it automatically counts as low status and causes one to be subject to immediate ridicule.

In any case, whether or not the debunkers are right about UFOs or any other particular case, there are at least two general things that they are definitely mistaken about. One is the idea that people who discuss such topics without complete agreement with them are automatically ridiculous. The second will be the topic of another post.

Extraordinary Claims and Extraordinary Evidence

entirelyuseless Logic, Mathematics, Probability , , , , ,

Marcello Truzzi states in an article On the Extraordinary: An Attempt At Clarification, “An extraordinary claim requires extraordinary proof.” This was later restated by Carl Sagan as, “Extraordinary claims require extraordinary evidence.” This is frequently used to argue against things such as “gods, ghosts, the paranormal, and UFOs.”

However, this kind of argument, at least as it is usually made, neglects to take into account the fact that claims themselves are already evidence.

Here is one example: while writing this article, I used an online random number generator to pick a random integer between one and a billion inclusive. The number was 422,819,208.

Suppose we evaluate my claim with the standard that extraordinary claims require extraordinary evidence, and neglect to consider the evidence contained within the claim itself. In this case, given that I did in fact pick a number in the manner stated, the probability that the number would be 422,819,208 is one in a billion. So readers should respond, “Either he didn’t pick the number in the manner stated, or the number was not 422,819,208. The probability that both of those were true is one in a billion. I simply don’t believe him.”

There is obviously a problem here, since in fact I did pick the number in the way stated, and that was actually the number. And the problem is precisely leaving out of consideration the evidence contained within the claim itself. Given that I make a claim that I picked a random number between one and a billion, the probability that I would claim 422,819,208 in particular is approximately one in a billion. So when you see me claim that I picked that number, you are seeing evidence (namely the fact that I am making the claim) which is very unlikely in itself. The fact that I made that claim is much more likely, however, if I actually picked that number, rather than some other number. Thus the very fact that I made the claim is strong evidence that I did pick the number 422,819,208 rather than some other number.

In this sense, extraordinary claims are already extraordinary evidence, and thus do not require some special justification.

However, we can consider another case, a hypothetical one. Suppose that in the above paragraphs, instead of the number 422,819,208, I had used the number 500,000,000, claiming that this was in fact the number that I got from the random number generator.

In that case you might have found the argument much less credible. Why?

Assuming that I did in fact pick the number randomly, the probability of picking 422,819,208 is one in a billion. And again, assuming that I did in fact pick the number randomly, the probability of picking 500,000,000 is one in a billion. So no difference here.

But both of those assume that I did pick the number randomly. And if I did not, the probabilities would not be the same. Instead, the fact that simpler things are more probable would come into play. At least with the language and notation that we are actually using, the number 500,000,000 is much simpler than the number 422,819,208. Consequently, assuming that I picked a number non-randomly and then told you about it,  is significantly more probable than one in a billion that I would pick the number 500,000,000, and thus less probable than one in a billion that I would pick 422,819,208 (this is why I said above that the probability of the claim was only approximately one in a billion; because in fact it is even less than that.)

For that reason, if I had actually claimed to have picked 500,000,000, you might well have concluded that the most reasonable explanation of the facts was that I did not actually use the random number generator, or that it had malfunctioned, rather than that the number was actually picked randomly.

This is relevant to the kinds of things where the postulate that “extraordinary claims require extraordinary evidence” is normally used. Consider the claim, “I was down in the graveyard at midnight last night and saw a ghost there.”

How often have you personally seen a ghost? Probably never, and even if you have, surely not many times. And if so, seeing a ghost is not exactly an everyday occurrence. Considered in itself, therefore, this is an improbable occurrence, and if we evaluated the claim without considering the evidence included within the claim itself, we would simply assume the account is mistaken.

However, part of the reason that we know that seeing ghosts is not a common event is that people do not often make such claims. Apparently 18% of Americans say that they have seen a ghost at one time or another. But this still means that 82% of Americans have never seen one, and even most of the 18% presumably do not mean to say that it has happened often. So this would still leave seeing ghosts as a pretty rare event. Consider how it would be if 99.5% of people said they had seen ghosts, but you personally had never seen one. Instead of thinking that seeing ghosts is rare, you would likely think that you were just unlucky (or lucky, as the case may be.)

Instead of this situation, however, seeing ghosts is rare, and claiming to see ghosts is also rare. This implies that the claim to have seen a ghost is already extraordinary evidence that a person in fact saw a ghost, just as my claiming to have picked 422,819,208 was extraordinary evidence that I actually picked that number.

Nonetheless, there is a difference between the case of the ghost and the case of the number between one and a billion. We already know that there are exactly one billion numbers between one and a billion inclusive. So given that I pick a number within this range, the probability of each number must be on average one in a billion. If it is more probable that I would pick certain numbers, such as 500,000,000, it must be less probable that I would pick others, such as 422,819,208. We don’t have an equivalent situation with the case of the ghost, because we don’t know in advance how often people actually see ghosts. Even if we can find an exact measure of how often people claim to see ghosts, that will not tell us how often people lie or are mistaken about it. Thus although we can say that claiming to see a ghost is good evidence of someone actually having seen a ghost, we don’t know in advance whether or not the evidence is good enough. It is “extraordinary evidence,” but is it extraordinary enough? Or in other words, is claiming to have seen a ghost more like claiming to have picked 422,819,208, or is it more like claiming to have picked 500,000,000?

That remains undetermined, at least by the considerations which we have given here. But unless you have good reasons to suspect that seeing ghosts is significantly more rare than claiming to see a ghost, it is misguided to dismiss such claims as requiring some special evidence apart from the claim itself.