Confirmation bias

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You will be familiar with the experience of the futile argument with to someone who holds a contrary idea to yours. If you're not, what the hell were you doing at university? The atheist who heckles the born-again preacher - or vice versa - will know this feeling. So will Marxists who engage capitalists, climate deniers who take on eco-warriors and anyone who's tried to querying force ranking with HR. This kind of arguments is fruitless, but thoroughly entertaining for the protagonists, at least until one pushes one hot button too far, and it’s all-out war.

It is pointless to argue across these intellectual divides because everyone who holds a view will accept as immutable proof of it any contention, however wan, which seems to support it, and will explain away, dissemble or, at the limit, flat-out ignore any assertion which tends to undermine it.

We all apply a rose-tinted filter, that is to say. Our acceptance of incoming information is biased in favour of what we want to hear - which confirms our existing narrative - and against information which undermines it. Hence confirmation bias.

See also

• The Structure of Scientific Revolutions — Thomas Kuhn’s wonderful book which explains this is a different, but just as compelling, way.
• Cognitive dissonance