This TED Talk features finance professor Alex Edmonds, recorded live at TEDx London Business School 2017.

Belle Gibson was a happy young Australian. She lived in Perth and she loved skateboarding. But in 2009, Bell learned that she had brain cancer and four months to live.

Two months of chemo and radiotherapy had no effect.

But Bell was determined.

She'd been a fighter her whole life.

From age six, she had to cook for her brother who had autism.

And to mother who had multiple sclerosis.

Her father was out of the picture.

So Bell fought with exercise, with meditation, and by ditching meat for fruit and vegetables,

and she made a complete recovery.

Bell's story went viral.

It was tweeted, blogged about, shared, and reached millions of people.

It showed the benefits of shunning traditional medicine for diet and exercise.

In August 2013, Bell launched a healthy eating app.

The Whole Pantry downloaded 200,000 times in the first month.

But Bell's story was a lie. Bell never had cancer. People shared a story

without ever checking if it was true. This is a classic example of confirmation bias. We accept a story

uncritically if it confirms what we'd like to be true

and we reject any story that contradicts it. How often do we see this in the stories that we share

and we ignore in politics, in business, in health advice.

The Oxford Dictionary's word of 2016 was post-truth,

and the recognition that we now live in a post-truth world has led to a much-needed emphasis on checking the facts.

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