Theory and Experiment

One of the most elegant things in science is the interplay between experiment and theory.  The experimenters find some relationship in the data they collect and the theorists come up with a model or explanation that fits the data.  The model makes specific predictions and the experimenters design ways to test the predictions.  The experimental results give the theorists something new to incorporate into their theories and the whole process goes on in a lovely self-correcting way.

I found a visual that brilliantly describes the way theory and experiment go together.  I've seen it in a lot of places, but I believe it is from Reddit user KTR2.  Enjoy:

Logical Fallacies - Post Hoc Ergo Propter Hoc

Do you not only want to be able to dismantle your friends' arguments, but also be able tell them the name of every mistake they make in their reasoning?  Then you should learn about logical fallacies!  Knowing about logical fallacies not only helps you avoid making your own logical errors, they give you a chance to teach everybody around you how to be less stupid!  Logical fallacies:  Learn about some today!  Guaranteed to make your friends and coworkers respect you even more*!

Lucky for you, I just happen to be writing about a logical fallacy right now, one known as "post hoc ergo propter hoc."  Literally translated as "after this, therefore because of this," post hoc ergo propter hoc is almost a sort of temporal periedolia.  Our brain notices that some action B happened after some other action or circumstance A and decides that this means A caused B.  It finds a pattern in time that can be used to explain something that happened and possibly predict when or if B will happen again.

I expect post hoc ergo propter hoc is responsible for a lot of superstitions, such as those followed by athletes.  If you had one of the best games in your life after a losing streak, you might ask yourself what was different before that winning game.  Maybe you ate some chicken and rice and all the other nights you had been eating beef and potatoes.  You might get it in your head that it was the chicken that caused your luck.  After that, there is no reason to risk not eating chicken.  Confirmation bias, the tendency to remember evidence that supports your beliefs rather than evaluating all evidence equally, helps here too.  You eat chicken before every game.  The games you win, you keep in your mind as evidence that chicken causes your to win.  The games you lose are forgotten.

Post hoc ergo propter hoc has some more serious effects than determining Wade Bogg's athletic ritual.  Doctors vaccinate children against measles, mumps, rubella, whooping cough and other diseases when the child is about 12 months old and again around the time the child enters preschool or school.  Autism diagnoses often come around this time as well.  The post hoc ergo propter hoc conclusion that the vaccines caused the autism can be a comforting thought when there is still much unknown about the condition.  But as Jenny McCarthy's crusade against vaccines demonstrates, such a conclusion does far more harm than good. Of course, Andrew Wakefield's fraudulent paper which "demonstrated" a link between vaccines and autism is also to blame, alongside other factors, for leading people to believe this false conclusion.  But now that you know we are prone to the post hoc ergo propter hoc fallacy, do try to avoid it.  I'd prefer it if polio and typhoid fever didn't make an epic comeback.


*Your results may vary.  Please use your well-informed understanding about how to construct logical arguments responsibly.  The Uraniborg blog and its writer do not condone condescension and general irritating know-it-all-ness.