At the beginning of the year, I gave a talk about “geopolitical risk” to a big conference of investors. I trotted briskly around the course: Russia, the Middle East, the South China sea, the eurozone. Afterwards, I was having coffee with one of the other speakers, a celebrated private-equity investor, and asked him how much he thought about geopolitical risk.

“Hardly at all,” he replied. “We look at the companies, the cash flows, the investments themselves.”

Since the man I was speaking to is a billionaire, who ended the conversation by offering me a lift to Madrid in his private jet, it would be foolish to dismiss his views. Most of the time, it does make sense for investors to treat the political news as background noise, which is only marginally more relevant than the sports pages. Events that are tragedies at a human level turn out to be irrelevant for investors. The unfolding war in Syria, which has claimed close to 200,000 lives, has taken place against a background of booming stock markets.