I am just working on a list of rationalist rules I live by, and this is the one I have most confidence in, so it seems a good topic for my first ever post (which will be short as I have to be on a train in 15)
Since people routinely exaggerate risk, and social norms pull us towards the crabs in a bucket effect (especially for women) I want to correct for that. (Preferably without ending up with a giant Rob Me sign over my head, but that's not the direction I err in.)
For example, there was this rationalist walked into a bar. I had a lot of luggage - everything I need for a four day break, including over two thousand pounds worth of electronic devices and binoculars. I am insured, but it would be an especially annoying time to lose stuff. I had a coffee and then I needed the bathroom, which was far away through a lot of people.
I knew logically how little risk there was in leaving all my stuff; a Highland bar in the middle of the afternoon is even safer than where I live in Edinburgh, and no-one was pinging any alarm bells, but I still spent more time than I'd like to admit convincing myself I didn't have to drag the huge bag with me to the ladies and back. Yes brain, even though I'm alone, and the customers are men, and I'm a middle aged woman, and my mother would freak if she saw me...
Of course it was fine, like it was the last hundred times. One day I hope to not even have to persuade myself, but meanwhile I notice my prediction was correct and feel just a little bit pleased with myself.
Getting to "know" a person, and sharing a social network with them, raises the cost to them of harming me. They would lose my good will, which could easily be more valuable in the long run than the contents of the bag. I could also harm their reputation by telling others about their crime, possibly costing them other friendships. There is also a filtering process in which evidence that people are likely to treat me badly leads to me not bothering to get to know them better.