Trusting like a Bayesian

A Bayesian mindset starts with an initial prior belief about an event. We then observe this event in real life and use the outcome of this event to update our prior belief. When we have to trust someone who we’ve never met before, we immediately feel uncomfortable. This is not because this person is truly a bad person, the problem is that we only have our prior to go off though and we humans are cautious by nature. When deciding whether or not we can trust someone, we are initially hesitant. Disagree? Then imagine letting someone you’ve known for 5 minutes look after your child or pet whilst you go away for the weekend. You’re unlikely to say yes. However, you might be willing to loan someone you’ve just met £5 if you see they’ve forgotten their wallet whilst paying for bread and milk. If this person repays promptly, then you may get talking and end up inviting them along to the book club you run. What’s happening here? Well, when this person repaid the £5 you loaned them, you observed a positive outcome and updated your prior to place a little more trust in this individual. Now you have a more positive and confident prior about this individual you’ve invited them along to your social circle. Without knowing it, you’ve made a Bayesian update to your belief. This, to me, is how most of us reason about decisions we must make everyday.