Post hoc ergo propter hoc

Hey, I learned a fancy new term today! Listen up, because I’m only going to share it once before I pretend I’ve never heard it and lock it away forever.

It all started this morning, when my friend Tallulah posted a link to a story on the CBC about a British medical journal that chose to retract a controversial study that it published in 1998, which linked the use of a certain vaccine in children to autism. “Take THAT, Jenny McCarthy (and irresponsible parents everywhere)!” Tallulah said in a post I can’t link to because her tweets are protected.

Admittedly, Jenny McCarthy’s probably better known for taking her top off a lot in the nineties than she is for having a medical degree or knowing what she’s talking about. But that doesn’t change the fact that a lot of people agree with her position that vaccines are bad news, and a few of those people chose to come forward in the comments section at the end of the CBC story.

“My son was developing normaly,” one father said, “until he recieved this vaccine at 18months. The next day he developped a fever. Within a week, he stopped speaking. A couple of months later he was diagnosed autistic. Can I prove the vaccine had an effect…NO. Can I find a few thousand parents with the same story…it might take a couple of days, but absolutely YES.”

“By your reasoning,” another commenter replied, “the cause of Autism could be potty-training. In fact, I bet I could get MORE data then you showing signs of autism occurred soon after potty training began. The mistake you have made is called ‘Post hoc ergo propter hoc’ (after this, thus because of this) and is a common error in logically thinking.”

There you go, guys. Post hoc ergo propter hoc. It’s one of those terms that was made for the Internet, wasn’t it? Nothing says “I’m an insufferable jackass who really ought to have better things to do” than telling someone on the web that the mistake they’ve made is called “post hoc ergo propter hoc.” And this was a guy who was not only right, but who was also actually one of the more polite and reasonable people in the thread! And to be fair, here I am, complaining about it from a distance after the fact!

I’m sure it goes without saying that the rest of the comments section was an absolute train wreck. If you’ve got a couple of hours to kill, and you feel like learning all about how the Nazis own all the drug companies and weed is the cure for everything and global warming’s a myth, then I highly recommend it. You’ll be questioning the right of everyday people to share their opinions in no time!

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