Intelligence can’t keep the entire population under surveillance and run precrime on people who are otherwise not suspects. For one, the idea that anyone could suddenly become a suspect because an algorithm determines from their credit card record, instant messaging keywords and/or fitness tracker readings that they may be suspicious is incompatible with a liberal society. Secondly, it wouldn’t work: terrorism is so rare that even an accurate algorithm would get mostly false positives.

Making it harder to get and keep guns does work. Civilians don’t need military-grade assault rifles in general, farmers don’t need an entire arsenal of firearms, and sporting shooters can keep their firearms in a secure locker at an accredited club facility, as they do in other countries.