Erin Welsh

What we believe to be true is not always what is actually true, something I'm sure we can all relate to.

Maybe you've debated with a friend over the answer to a trivia question, like you both know the right answer, but your answers are somehow different.

Or maybe you've had a heated exchange with a relative who firmly believes that the moon landing was faked.

How do we decide what we believe?

How can we know that what we believe is the truth?

And how can we convince others of that?

These are precisely the questions that Adam Kucharski, who is professor at the London School of Hygiene and Tropical Medicine, asks in his latest book, Proof, The Art and Science of Certainty.

Kucharski, who is a mathematician that works on infectious disease outbreaks, explores how we are inundated with information and increasingly misinformation that we have to evaluate to determine whether or not we should incorporate it into our decision making.

This extends beyond personal decisions, which route is best to take to work, what to make for dinner.

Our world is built upon structures of proof with varying degrees of support.

That car that you drive to work is manufactured under rigorous safety testing, meaning there are established guidelines for what is considered safe and how to test that.

Same thing with the food we eat, the medicines we take, the buildings we spend time in.

We don't question so many of our beliefs.

To do so would leave you frozen, uncertain of which direction to move in, what to trust.

You'd have no time to actually live your life.

But when we do scrutinize our certainty, we might find a gulf between our beliefs and someone else's, and those beliefs and the objective truth.

Where does that incongruity originate?

Why are we skeptical about some things and not others?

What does it take to make up our mind?

And what does it take to change it?