It's fashionable among academics and pundits to proclaim that the U.S. is in decline and no longer No. 1 in the world. The declinists say they are realists. In fact, their alarm is unrealistic.
Early declinists like Yale historian Paul Kennedy focused in the 1980s on the allegedly debilitating effects of America's "imperial overstretch." More recently, historians Niall Ferguson and Martin Jacques focus on the weakening of the economy. Among pundits, Paul Krugman and Michael Kinsley on the left and Mark Helprin on the right sound the alarm.
The debate involves issues of absolute versus relative decline and concepts like "resilience" and "passivity." Some issues are measurable, like gross domestic product (GDP), military power and demographics. Others are not measurable or less measurable.