Malcolm Gladwell on Competing Security Models

In this essay/review of a book on UK intelligence officer and Soviet spy Kim Philby, Malcolm Gladwell makes this interesting observation:

Here we have two very different security models. The Philby-era model erred on the side of trust. I was asked about him, and I said I knew his people. The "cost" of the high-trust model was Burgess, Maclean, and Philby. To put it another way, the Philbyian secret service was prone to false-negative errors. Its mistake was to label as loyal people who were actually traitors.

The Wright model erred on the side of suspicion. The manufacture of raincoats is a well-known cover for Soviet intelligence operations. But that model also has a cost. If you start a security system with the aim of catching the likes of Burgess, Maclean, and Philby, you have a tendency to make false-positive errors: you label as suspicious people and events that are actually perfectly normal.