More logical fallacies

Last week we covered logical fallacies and today was no exception. There are so many of them that it really takes a while to go over. Each time I do it I think of a few that I should have left out and a few that I should have included. I suspect I’ll have it correct in about five years.

Today we covered:

Correlation vs. Causation – assuming cause and effect for two things simply because they occurred together

Unexplained vs. Unexplainable – believing that because we cannot explain some phenomenon now, we will never be able to explain it

False continuum – thinking that because no distinct line exists between two extremes, then those two extremes are really the same thing

False dichotomy – insisting that things must either be one way or another

Inconsistency – applying criteria to one thing but not to another

Non-Sequitur – making a conclusion that doesn’t follow from the arguments

Post-hoc ergo propter hoc – saying that because A happened before B, A must have caused B

Reductio ad absurdim – extending an argument to an absurd conclusion

Ad hominem – attacking a person, rather than their claims

Slippery slope – arguing that believing  something must also involve believing in its extreme

Special pleading – arbitrarily introducing something into an argument to make it work

Fatty fat fat!

It might like a tall order to keep a room full of 12 – 14 year olds interested in this material but I have to tell you, they love it. They were by far the most popular sessions I ran last year and this year seems no different. As soon as I’d mention a different fallacy kids around the room would be raising their kids (or just blurting out) and giving examples they’ve come across.

I’ve found that giving funny examples can really help to both get the point across and keep the kids listening. My favourite correlation/causation example claims that global warming is caused by the decline in piracy. The amount of pirates negatively correlations with global temperatures. Ergo, we need to bring back pirates.

I like to prove to my kids that tall people have bigger vocabularies. My argument goes that small babies have small vocabularies. As they grow taller their vocabularies increase. Ergo, tall people have larger vocabularies.

Examples like this make it perfectly clear what the mistake is. Being able to spot the error in an easy example is a good start to being able to spot more its subtle uses.

Post-hoc ergo propter hoc can be explained by claiming that because a rooster crows before the sun rise, a rooster’s crow causes the sunrise. It’s a variant on the correlation/causation fallacy but from slightly different angle. The two events aren’t happening concurrently, rather sequentially.

My goal now is to put these fallacies into a small booklet for the kids. This will save me from having to go over them several times, hopefully. There are two iPhone apps which I have installed and will give a review of in the next few weeks. I like the idea of my kids running around with logical fallacy databases in their pockets. I don’t know how much nerdier you can get.


1 Comment

Filed under McKinnon Secondary Sceptical Society

One response to “More logical fallacies

  1. I just love it. A graph! A graph! Even Stephie Graf! There IS hope that teachers like you may balance, or at least create a blip on the radar, opposing the dumbing down of our young people. We’ve gotten too big for our britches, we simply can’t be bothered to fully educate our little ones. Oh, the price we will pay. Thank you for your endeavor!

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s