An Object Lesson in Critical Thinking

     We are awash in a sea of ignorant nonsense and insidious propaganda, thanks in no small part to social media and the ease with which we can share any attention-grabbing meme that crosses our path. Pedantic spoilsports like me can try patiently to debunk them, one by one, but in the long run the most important defence will always be the critical thinking capacity of the audience. We need to learn how to read intelligently, so we won't be as easily taken in by ridiculous claims. To that end, I'd like to walk you through a particularly silly chain letter that's come across my feed at least a dozen times over the last few years. I want to show one approach to recognizing its nonsense by drawing on really very basic background knowledge and applying it.

     Here's the specimen:

     I'll type in the text directly, so people googling for it can find it here.

GOOD LUCK EVERYONE !!! This year December has 5 Mondays, 5 Saturdays and 5 Sundays. This Happens once every 823 years. This is called money bags. So share it and money will arrive within 4 days. Based on Chinese Feng Shui. The one who does not share, will be without money. Share within 11 minutes of reading. Can't hurt so I did it. JUST FOR FUN.

(Not gonna type in the Facebook URL. If you really want to reward the purveyors of such nonsense, type it in yourself.)

     So, there are a few questions that are good to keep in mind while considering, well, anything anyone tries to tell you, ever.

(1) Who is telling me this and why?
(2) How do they know what they're telling me?
(3) Is it logically consistent with itself?
(4) Is it consistent with other things I know?

     These questions aren't the only or best ones to ask, but they are helpful. So let's try to apply them to the meme.

(1) Who is telling me this and why?
     This is actually a pretty difficult question with memes in general, because the person who shared it with you is rarely the original author, although by sharing it you can assume they're at least endorsing the contents to some extent. But this one in particular is especially tricky, because it is explicitly self-referential. It talks about what will happen if you share it and what will happen if you don't, and specifies how long it will take for the money to arrive and how quickly you must send it out. It even explicitly says "Can't hurt so I did it". Did what? Forwarded the meme you just received? But then the "I" here doesn't refer to the original author, but the most recent forwarder.
     So who is actually making these claims, that this is based on Chinese Feng Shui or that it only happens every 823 years or that I'll receive money if I share it? Maybe the owner of the Facebook page referred to at the bottom, but probably not even them, given how many such pages repurpose and resend this kind of thing.
     There's no obvious way to track down the original author, but we can consider a couple of likely motives, based on the content.
     Maybe they believe it, and want to send good luck to everyone?
     Maybe they want to compile a list of suckers who respond to chain letters?
     Maybe, as they say, they really are doing it "JUST FOR FUN"? (Personally, I fail to see the fun in it, but I am, after all, a pedantic spoilsport.)

(2) How do they know what they're telling me?
     This is only an issue if you think they believe it and want to send good luck to everyone. As far as your friend who shared it is concerned, they "know" it only because they received a chain letter telling them all this stuff; in other words, they are in exactly the same epistemic position you are, since you've received the same chain letter. So how do you know this letter is true? You don't, and neither did the person who forwarded it to you, so you cannot rely on your friend's testimony.
     But the problem gets worse as you look deeper. How did the original author know any of this stuff? They're claiming that you'll receive money within four days, if you send it out within 11 minutes. They couldn't know this by experimentation and observation of how long it takes people to reply and which ones ended up rich or penniless, because that data could only have been obtained after they sent out the chain letter, and that would make this a different letter from the first one they sent out. I suppose we could imagine some powerful wizard or psychohistorian, learned in the arcane rules that govern mystical runes of luck magic, might derive a text from some formula and confidently predict that this particular text will produce these effects. If you think that's plausible, then maybe you might want to forward that chain letter promptly, but I think it's reasonable to expect a little more evidence before just inventing such a bizarre claim and assuming it to be true.

(3) Is it logically consistent with itself?
     All by itself, it's not obviously self-contradictory, except for the bit where it says, "Can't hurt so I did it." But it also says "The one who does not share, will be without money." And it promises that if you do share, you'll receive money, so clearly it is claiming to have some kind of power to benefit or harm people, depending on whether or not they share it. So which is it? Can it hurt, or not?
     Alternatively, the "Can't hurt" may only refer to how it can't hurt if you comply within 11 minutes, but it can mess you up bad if you ignore it. So it's not necessarily self-contradictory. But it doesn't inspire a great deal of confidence.

(4) Is it consistent with other things I know?
     Here's where we'll differ; we know different things. But this chain letter is inconsistent with some things that pretty much everybody knows, although it takes a bit of analysis to see this.
     First, a quick look at the calendar will show that, in fact, December 2016 only has four Sundays and four Mondays. The chain letter is simply wrong about "this year", but perhaps it was written for a different year and is just still in circulation. (I googled for the phrase "Saturday, December 1" and quickly learned that there was such a Saturday in 2012.)
     Second, it stands to reason that for a 31 day month like December to have five Saturdays, Sundays and Mondays, December 1 must fall on a Saturday. There are only seven days of the week to choose from, so unless there's some complicated math involved, you'd expect a "money bags" December every seven years or so, not every 823 years. But maybe leap years mess it up somehow?
     So let's think about that a bit. There are 7 possible regular years, one starting on each day of the week. And then another 7 for leap years, for a total possible 14 unique calendars. Since a leap year comes every four years, it would take 28 years to cycle through all 7 available leap years, and then that same cycle would repeat exactly, during which time there would be several regular years that also had a "money bags" December.
     Yet the chain letter tells us it happens only once every 823 years? That's just not consistent with what every school kid knows about the Gregorian calendar. Unless I've done my math wrong, it just seems plain flat out wrong, and quite ridiculously so.

     There's more, of course. "Based on Chinese Feng Shui." Really? I am no expert on Feng Shui, but I've got some exposure to Chinese culture, and as I understand it, Feng Shui is a set of principles for arranging furniture and architecture and the like in harmonious ways. Some talk about it as channelling good luck energy, but others say it's just about aesthetics and ergonomics. In any event, I don't see how it relates to calendars, and what's more, the traditional Chinese calendar is lunar, and doesn't involve 31-day months called "December" at all. I suppose it's possible some Feng Shui specialist applied their theory to our western Gregorian calendar and came up with this "money bags stuff", but it seems more likely to me that some nitwit who knows even less about it than I do decided to lend false authority to their ridiculous chain letter by referencing Mysterious Secrets of the Inscrutable Orient.


     I know the chain letter says "JUST FOR FUN", and I hate to be a spoilsport, but this is getting to be pretty serious. There's a lot of really, really stupid and dangerous stuff circulating right now, and people are making dangerous decisions based on it. Good, independent critical thinking habits must be practiced and cultivated until they become natural and instinctive. Conversely, every time you uncritically click "Share" on something like this, you're actually practicing and reinforcing bad habits of gullibility, and you're encouraging other people to do the same.

     THINK!