HNN has posted reporting by its editor, Rick Shenkman, from the recent AHA convention in D.C.
One of the speakers, a government functionary named Philip Zelikow, gave a talk on contingency in history that Shenkman labels "extraordinary" and "stunningly sophisticated." Discount that somewhat: an AHA attendee is, after all, normally fed milk and cookies.
Despite the hype, it's worth watching the two 10-minute videos provided by HNN. As an observer of decisions in government, Zelikow notes "... the outcomes are often highly discontinuous, unexpected, and non-linear." Zelikow says that historians look at crises from 10,000 feet up and cannot thereby account accurately for contingency.
In the first video, you'll see Zelikow reading from Edward Ayers - an especially rich Blundering Generation passage that argues the Civil War came as an earthquake with nothing inevitable about it. This is his starting point for contingency discussion. In the second video, Zelikow addresses how badly wrong top-down histories of the Cuban Missile Crisis got it, how the tiny telling details recently discovered turned conventional histories around.
Go to the link above and scroll way down to the YouTube controls and see for yourself. Then, if you'd like to know how governments and their advisors currently plot alternative futures, go here and have a good long read. (I think some of the methodologies you'll find can map backwards into historical contingency analysis.)