SCOTT THOMPSON, one assumes, is a clever man. And yet the new chief executive of Yahoo has done something incredibly stupid. Claiming to have a degree in computer sciences and accountancy when you’ve only got a degree in accountancy is an idiotic thing to do.

Quite possibly the people at Diageo are also clever enough. But preventing a little brewer from winning a prize last week was a fabulously boneheaded piece of work.

Most definitely the bankers at JPMorgan are clever. Too clever by half, one might say. But that didn’t stop them losing $2 billion through what its chief executive Jamie Dimon called “error, sloppiness and poor judgment”.

Nearly always, it’s the bad little things we do that get us into the biggest trouble. It’s the things that we know are stupid even at the time we are doing them, but do anyway.

There is a new word for the idea of smart people making moronic errors: “disrationalia”. It has been coined by Keith Stanovich, a psychologist at the University of Toronto, who argues that we are preprogrammed to make daft mistakes. Partly it’s because we think we are better than we are. We also look for evidence that supports what we believe. And we get easily distracted.

To understand how deep this human stupidity goes, I need look no further than myself. Only last week I managed to say something disparaging in an open-plan office about a colleague – only to find the man in question standing behind me. My gaffe was relatively unserious because it was low-tech. I wasn’t linked to a microphone or connected in any way, so only three people were involved.

Thanks to mass-connectivity, most small gaffes are no longer small – they are ginormous. The internet made it much easier to detect the Yahoo CV cock-up and then for the world to make a great stink about it.

Email – as well as texting – is still the fastest way to get into huge trouble over not very much. Never mind that we all know perfectly well that we must never write anything in a work email that we would not be happy for the world to see, the penny still isn’t dropping.

The people at Goldman Sachs are as clever as they come, and the corporate bellowing of ethical messaging couldn’t be louder. But that didn’t stop former trader Fabrice Tourre from boasting in an email about the “pure intellectual masturbation” of a product he had created and how the market was too stupid to price it. More recently, the bank was on the defensive again, hunting through its emails to find the culprits who had apparently been calling clients muppets.

It’s not just that we take no care over what we say in emails. We can’t even address them to the right person. Ten years after the invention of electronic messages we still haven’t learnt to get the correct name in the address field.

Last week, Eastern Michigan University managed by mistake to sack the entire student body, sending everyone a message that was aimed at just a few. It told them their academic performance was not up to scratch and they were being kicked out. The same day, I got a text from my usually technically competent son that he had intended to send to a friend, in which he reported that his mother had turned into a mad woman.

Is there any chance that we will ever learn anything? For me, it’s not looking good. Last week I took a solemn vow that I would never say anything about a third party unless I was locked in a soundproof cell. But I’ve made a similar vow a hundred times in the past, and broken it equally often.

I’ve been sifting through expert papers on this and there seems to be a consensus that the only way to stop making small mistakes is to understand why we make them.

I understand why I say bad things about people: to amuse the person I’m talking to, because I like saying what I think.

I can also see why people falsify CVs: to make themselves look better. I suppose people fiddle prizes for the same reason. And, above all, I can understand why we are sloppy and careless – because it’s a lot less effort than being careful. The easiest thing is to understand why we always think we’ll get away with it – because we did last time, because we know others have and because it’s what we want to believe.

I’ve understood all this for a long time. But I also understand that understanding it isn’t going to make a shred of difference. Any company that thinks it can reprogramme our “disrationalia” with a few rules and ethics courses is not making a small mistake. It is making a huge one. – (Copyright The Financial Times Limited 2012)