The Crowdstrike fiasco is a lesson in the importance of building resilience — on a societal and individual level, Glenn Reynolds says.

On social media I see people stranded in Paris with no working credit cards and dead ATMs, and that leads to another important lesson: Always carry cash! When traveling, I generally carry enough cash to get me through at least a couple of days (often more) and even at home I keep some cash in case things don’t work right.

Back in the 2003 New York blackout, Amy Langfield wrote about the value of keeping a stash of small bills that she could use at the bodegas when the credit/debit card machines were down. The cashless society depends on the flawless functioning of networks that aren’t really secure or reliable. Cash carries its own information with it – a $20 bill is worth $20 – and you don’t need to know more to spend or accept it. That’s resilient. Likewise making sure you have plenty of cushion with regard to supplies of medication, food at home, and the like.

I think about preppers sometimes. They have a reputation as kooks. But natural disasters happen. Utility grids fail. It’s a good idea to have a few weeks’ supply of shelf-stable food, drinking water and meds on hand, as well as the means to bug out if you need to.