ROME — I got a call last week from an Italian friend, an investigative reporter. He had just spoken to an Italian magistrate who wanted to sound out a theory.

The magistrate wondered — in all seriousness — if my recent article in The New York Times about Prime Minister Silvio Berlusconi’s personal life could be evidence that Mayor Michael R. Bloomberg, envious of Mr. Berlusconi’s media empire, was using me to take down the prime minister.

My friend quickly and rightly dismissed the theory for what it was: insane. But the fact that it had been advanced by a respectable magistrate tells you almost everything you need to know about how power operates in Italy. It also goes a long way toward explaining the unstoppable success of Mr. Berlusconi, a phenomenon as alien to Americans as conflict-of-interest laws are to Italians.

Americans are forever asking how Italy can keep …