Posts Tagged 'Logic'

Post Hoc Ergo Propter Hoc – Why my iPod Didn’t Kill my Computer

Post Hoc Ergo Propter Hoc is Latin for “after this, therefore because of this,” or in other words, associating correlation with causation.

People are notorious for making this error in logic, because when something significant happens we want to be able to know & explain why it happened.

I was guilty of this error the other day when my laptop broke (I lost all of my files, I cried and learned my lesson – back them up!!!). I was going about my computer business as usual, and remembered that my iPod battery was nearly drained, so decided to plug it in. As soon as the cord hit the USB port, the screen went black, it crashed, and I couldn’t turn it back on.

I blamed this crash on the iPod, I even yelled at it and threw the cord against the wall! But when my husband took it in to get fixed, they said it wasn’t possible that the iPod was what caused the problem. Sorry iPod, it was just a coincidence that my computer happened to die at the exact moment that I plugged it in. I think this is a great example that helps to understand why many people buy into the anti-vaccine movement in spite of the complete lack of evidence correlating vaccines with autism.

Just like a certain amount of peoples’ computers will crash shortly after they plug their iPods into their USB ports, a certain number of children will be diagnosed with autism shortly after they are immunized. Just because it happens before, doesn’t mean it was the cause.

There’s a story that Paul Offit, author of Autism’s False Prophets, likes to tell that illustrates this beautifully:

My wife is a privately practicing pediatrician in the suburbs. And she was in the office one day and there was a four-month-old sitting on her mother’s lap. And my wife was drawing a vaccine into a syringe that she was about to give this child. Well, while she was drawing the vaccine into a syringe the child had a seizure, and actually went on to have a permanent seizure disorder—epilepsy. And there had been a family history of epilepsy, so she was certainly at risk for that. If my wife had given that vaccine five minutes earlier, I think there’s no amount of statistical data in the world that would have convinced that mother that anything other than the vaccine caused the seizure, because I think those sort of emotional events are very hard to argue against.

Can Your Beliefs About Religion make it Across This Intellectual Battleground?

The Philosophers’ Magazine has an interesting little test to see how reasoned your beliefs about religion are.

Give it a try: Battleground God

I suggest you try the test before reading my results below.

I was awarded this:

It’s given to about 46% of people who complete the test, because I didn’t take any “hits”, and only “bit one bullet”.

Here’s what it said about me:

You have been awarded the TPM medal of distinction! This is our second highest award for outstanding service on the intellectual battleground.

The fact that you progressed through this activity without being hit and biting only one bullet suggests that your beliefs about God are internally consistent and well thought out.

A direct hit would have occurred had you answered in a way that implied a logical contradiction. The bitten bullet occurred because you responded in a way that required that you held a view that most people would have found strange, incredible or unpalatable. However, because you bit only one bullet and avoided direct hits completely you still qualify for our second highest award. A good achievement!

The question I bit the bullet on was this one:

You answered “True” to questions 6 and 13.

These answers generated the following response:

You stated earlier that evolutionary theory is essentially true. However, you have now claimed that it is foolish to believe in God without certain, irrevocable proof that she exists. The problem is that there is no certain proof that evolutionary theory is true – even though there is overwhelming evidence that it is true. So it seems that you require certain, irrevocable proof for God’s existence, but accept evolutionary theory without certain proof. So you’ve got a choice: (a) Bite a bullet and claim that a higher standard of proof is required for belief in God than for belief in evolution. (b) Take a hit, conceding that there is a contradiction in your responses.

I chose option a, because I feel that the evidence for god would have to be exceptionally strong to convince me. If I were asked the question again though I would probably have to change my answer. The evidence for evolution is so good that an equivalent standard of evidence for god should be enough to convince me, and I hope would convince me that there’s a god.

As far as I know, no scientific theory has “certain, irrevocable proof.” I’m pretty sure that proofs only exist in mathematics. My logic faltered there, but I know that I should hold the same standards of evidence for anything that I hold to be true.


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