Common sense isn’t always that sensible


Teens are rebellious, and try anything they’re told not to do.

Photo credit: Samuel Muigai | Nation Media Group

You would be surprised how often our ‘common sense’ ideas turn out to be completely wrong. For example, public health campaigns that try to scare young people away from drugs actually make matters worse. Teens are rebellious, and try anything they’re told not to do.

A much more successful approach is to help children deal with the issues that tempt them to try drugs in the first place.

Another example is that over a third of perfectly healthy people experience hallucinations at some point in their lives. But somehow we’ve all got the idea that hallucinations only happen to people who’re high, or suffering from a mental illness. So despite being almost normal, hallucinations cause a lot of distress.

Lots of other common sense ideas also turn out to be wrong. Like the belief that we have to teach children to talk. Actually we don’t, they’re programmed to teach themselves. All they need is ample exposure to language.


People often say that facts like these are ‘obvious.’ But that’s only because all the best ideas are obvious after you’ve heard them. They weren’t so obvious before though! And it’s also easy to confuse familiarity with understanding. Try asking your friends to explain how a few everyday objects work, like a radio, toilet flush or door lock. Chances are they’ll say they know, but most people can’t actually explain how they work if you ask. Or fix one if it’s broken.

So one way researchers make sure their results aren’t obvious is to ask people what they think the result will be before they start work. That was done before studying what people would do if they were asked to hurt someone. Everyone says they’d refuse, but the fact is that most ordinary people, and not just psychopaths, are easily persuaded to hurt someone if they’re told to by an authority figure.

Another good example is asking people whether they’d be more likely to sound their horn at a big flashy car or a battered old wreck. Everyone says that the size or status of the car would make no difference, but in fact most people only hoot at bangers!

Contradictory beliefs

We’re also quite happy to hold contradictory beliefs. Like ‘absence makes the heart grow fonder’ and ‘out of sight, out of mind,’ even though they can’t both be true! But it’s not really surprising we believe things that aren’t rational. Think about some of the things people believed in times gone by. For example, for most of human history people believed that malaria was caused by ‘bad air,’ which is what the word means. It’s spread by mosquitoes of course.

The problem is that we rarely challenge our beliefs, or try to understand why we behave the way we do. So the next time your spouse does something utterly maddening, don’t just get annoyed. Try and figure out exactly why their behaviour is upsetting you. Your life will become far better if you do.


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