I just saw "World War Z" yesterday, a zombie apocalypse premise. It contained an interesting discussion on Israel's "10th Man" doctrine. Allegedly, if 9 people in a room agree on a certain thing it is the DUTY of the 10th man to disagree.

"Following the Yom Kippur War (1973) which took Israeli military intelligence by surprise, institutions were put in place to reduce the chances that group think and overly dominant commanders would prevent diverse opinions from reaching decision makers or from being initiated at all. One of these was a unit often referred to as the devil's advocate office.

As described by Yosef Kupperwasser, who used to head the Research Division of the IDF, in Lesson's From Israel's Intelligence Reforms [1]:
The devil’s advocate office ensures that AMAN’s intelligence assessments are creative and do not fall prey to group think. The office regularly criticizes products coming from the analysis and production divisions, and writes opinion papers that counter these departments’ assessments. The staff in the devil’s advocate office is made up of extremely experienced and talented officers who are known to have a creative, “outside the box” way of thinking. Perhaps as important, they are highly regarded by the analysts. As such, strong consideration is given to their conclusions and their memos go directly to the office of the Director of Military Intelligence, as well as to all major decision makers. The devil’s advocate office also proactively combats group think and conventional wisdom by writing papers that examine the possibility of a radical and negative change occurring within the security environment. This is done even when the defense establishment does not think that such a development is likely, precisely to explore alternative assumptions and worst-case scenarios.

[1] http://www.brookings.edu/~/media..."

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