This is the inquiry on the BBC World Service.

I'm Ruth Alexander.

Each week, one question, four expert witnesses and an answer.

It's 1894 in Paris. A woman empties the waste bin in the German attaches

the waste bin in the German attaches office and, as usual, takes the contents to the French Secret Service.

In amongst the rubbish is a torn-up note.

Peased together, it reveals a French army officer has offered to sell military secrets to the Germans.

A Jewish artillery captain from Al-Sass, a Germanic part of France, is soon identified as the chief suspect

and quickly arrested. His handwriting is analysed. It doesn't match that on the note. But as an expert testifies, well that just

shows he must have disguised his own hand. The officer's house and belongings are searched. No evidence is found, but that only

proved how devious he is. Captain Alfred Dreyfus was publicly humiliated and sentenced to life imprisonment.

The case split France. A campaign began for his release, but it took 12 years before he was exonerated.

More than a century on, the Drafus affair is still regarded as a prime example of our capacity to ignore facts and only believe what

we want to believe, something which experts today say is getting worse. So this week we're asking, why don't we care about facts?

Part 1. Group Think.

People think.

People think that they think like scientists, but they really think like attorneys.

Our first expert witness is Peter Ditto, professor of psychological science at the University of

California Irvine.

We all have this image of ourselves as kind of rational information process, there's where many of us do.

So we think like scientists ideally do, you know, build the information from the facts and we come to some

conclusion based on a bunch of facts. But, you know, attorneys on the other hand harness a set of facts

...