Scientific Proof – Politicians are Stupid

Have you ever wondered why people hold onto their beliefs despite statistical proof that they are wrong?

  • Is it that we don’t understand what the numbers are telling us?
  • Or is it that we just chose to ignore them?

Dan Kahan is the professor of Law and Politics at Yale University.  This question perplexed him.  So he ran an experiment with a thousand students, and this is what he found out

Some of us aren’t very good at maths all of the time

In his first experiment the students were given data from a skin care cream trial and asked if the cream worked.  Not all the students could work out the answer.  Professor Kahan proved that maths is complicated.

and some of us aren’t very good at maths some of the time

The second experiment involved the same people and the same data but this time the subject was a gun control experiment (a highly charged political issue in the States).

Unsurprisingly the students who couldn’t figure out the skin care problem failed again.  But this time a large proportion of the people who had proved they could do the maths got it wrong as well.

Politics makes us stupid

  • The data was rigged so it was pro gun control
  • The data was rigged so it was anti gun control

Left or right, it didn’t matter, the drop in mathematical ability was the same.

Professor Kahan showed that if the data is counter to our political leanings then we are far more likely to jump to a conclusion that supports our view of the world and come up with the wrong answer.

We see what we want to see

Our businesses are rife with politics, bias and beliefs, it is part of the human condition.

So the next time your analysis suggest something contentious it is worth spending the time to make sure your presentation of the numbers is absolutely clear and unambiguous.

  • Both for those who can’t do the maths
  • And also those who can, but just might not like the answer

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Image by the World Bank Photo Collection


  1. Hi James,
    Numeracy aside, does this not also prove that we have to fight to get through the cognitive dissonance that exists in much of what we do?


  2. James,

    All you can do is present the facts (or data), right? Everyone will interpret it differently… or do with it what they will. And sometimes we just don’t like what the data tell us…

    I’m thinking about a recent experience with a client. The data told them something they didn’t want to hear. I didn’t make up what the analysis told us… it was right there in black and white. They chose to ignore it.

    Annette :-)

  3. Mark Gilbert says:

    I listened to a BBC Radio 4 programme concerning this. Very similar to confirmation or optimism bias. But I tend to stay away from terms such as ‘Scientific Proof’ in favour of ‘Empirical Evidence’. Otherwise you end up with a crutch made of chocolate in hot weather. Another rendition of bias. We believe people have a tendency in a designed/controlled trial, etc. etc. etc…

    • James Lawther says:

      Very true Mark, I’m a guilty of sensationalism, unfortunately “Empirical Evidence that Politicians are Stupid” doesn’t have quite the same draw.


  4. Hello James,
    It occurs to me that perhaps you have really gotten the beauty of the being of human being. Allow me to share a story me that gets at the true wonder of human being.

    An experienced therapist is working with a client who is convinced that he (the client) is dead. After some sessions, the therapist has built enough rapport. Now the therapist feels ready to ‘present the numbers’ as it were – in a rather clear cut manner.

    The therapist, asks “Dave, do dead people bleed?”

    Dave responds, “Don’t be ridiculous! Dead people don’t bleed, only the living bleed.”

    Suddenly the therapist lunges out of chair, cuts Dave’s hand with a knife. And red blood starts to flow. Seeing the blood and seeing that Dave is seeing the blood, the therapist smiles. Why? He is convinced that he is shown Dave the indisputable data – the data that Dave needs to see that he is not dead.

    What does Dave say?

    Dave says “F**k me, dead people do bleed!”

    Enough said. I hope you enjoyed the story.


  5. Nice work James,

    The same is true in corporations during business decision making, I see it frequently. Most of the time people make pre-favored decisions after viewing the data and they find ways to justify it.

    Which leaves me thinking, what is the root cause? Is it not having the ability to comprehend the data when it’s contradictory to personal belief, or is the data recognized and willfully ignored in favor of predisposed opinions?

    I will read your paper shortly, I’m very curious now.

    • James Lawther says:

      If I understand it properly it is a little more nuanced than that, we look at the data and then mange to convince ourselves that it is telling us what we want to here. We are very good at self delusion. Thanks for the comment

  6. Just goes to show as somebody smarter than me observed, “You just can’t fix stupid!”

  7. Tito Coronado says:

    The movie “The Challenger Disaster”( recounts the problem analysis associated with the loss of the Challenger Space Shuttle. It is a study in exactly the kinds of issues described here.

    If you are interested in gaining some insights it is a good watch, not a great plot and the conclusion is well documented, but there is much to learn from it.


    – Tito

  8. Usually statistics are very shallow and many times they are created with a goal of persuasion in mind. Your gun control example is a great one as both sides of the issue throw out incredibly swayed stats. For example, they say, “The number of people killed by their own gun is greater than crimes stopped with a gun.”. Ask one question, “How many people had accidents that also had gun safety education.”. Nobody knows because that would have swayed the persuasion that the statistician was shooting for. Then throw in that nobody knows how many crimes were actually stopped because, well, they were stopped and may have gone unreported.

    Now tell that stat to a farmer in the middle of nowhere who needs to protect his supplies from meth dealers. He’s shot weapons for 50 years with no incidents. Some would call him the ignorant one for ignoring their “facts”.

    I’ve seen presentations that are this ridiculous with other matters and it’s tiring to see the person presenting the “facts” become disgusted when he discounts the non-believers as the stupid ones.

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