{"id":3288,"date":"2026-04-06T12:40:08","date_gmt":"2026-04-06T10:40:08","guid":{"rendered":"https:\/\/www.jorgebalaguer.com\/blog\/?p=3288"},"modified":"2026-04-06T12:40:08","modified_gmt":"2026-04-06T10:40:08","slug":"the-tenth-mans-rule","status":"publish","type":"post","link":"https:\/\/www.jorgebalaguer.com\/blog\/the-tenth-mans-rule\/","title":{"rendered":"The Tenth Man&#8217;s rule"},"content":{"rendered":"\n<p>Recently, I\u2019ve stumbled down a bit of a rabbit hole that led me to an interesting text. I watched World War Z a few years ago (in my opinion, the book is far more engaging than the film, and with fewer gory scenes), and I still remember the allusion to the &#8216;Tenth Man Rule.&#8217; Supposedly, this is a rule used by Israeli Intelligence where, if nine advisors agree on a conclusion, the tenth is required to disagree and adopt a contrarian viewpoint. This helps avoid groupthink and complacency, while preparing for low-probability &#8216;black swan&#8217; threats.<\/p>\n\n\n\n<p>That led me to do some research looking for a non-fiction source, and Reddit pointed me to a paper titled <a href=\"https:\/\/www.brookings.edu\/wp-content\/uploads\/2016\/06\/10_intelligence_kuperwasser.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">Lessons from Israel\u2019s Intelligence Reforms <\/a>by J. Kuperwasser. The reading is surprisingly easy (I wonder what kind of documents I\u2019m used to reading if an academic military paper feels easy to me\u2026).<\/p>\n\n\n\n<p>In the document, Mr. Kuperwasser doesn\u2019t mention the &#8216;Tenth Man Rule&#8217; using those exact words. Instead, he uses a more classic and well-known figure: &#8216;The Devil\u2019s Advocate.&#8217; In the words of the author:&#8221;<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>The devil\u2019s advocate office ensures that <a href=\"https:\/\/en.wikipedia.org\/wiki\/Military_Intelligence_Directorate_(Israel)\">AMAN<\/a>\u2019s 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\u2019 assessments. The staff in the devil\u2019s advocate office is made up of extremely experienced and talented officers who are known to have a creative, \u201coutside the box\u201d way of thinking. Perhaps as important, they are highly regarded by the analysts. (page 4).<\/p>\n\n\n\n<p><\/p>\n<\/blockquote>\n\n\n\n<p>But the question is: Is your organization resilient enough to cope with internal criticism? Are you sure that you or your colleagues promote this kind of behavior? I often see how people, perhaps unconsciously, disapprove of criticism regarding their way of thinking about a subject. AMAN also provides an institution-level measure:<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>While the devil\u2019s advocate office is an institutional-<br>level safeguard against group think, there is also an<br>individual-level safeguard. The analysts themselves<br>are given venues for expressing alternate opinions.<br>Any analyst can author a \u201cdifferent opinion\u201d memo in<br>which he or she can critique the conclusions of his or<br>her department. Senior officers do not criticize ana-<br>lysts who choose to write such memos.<\/p>\n<\/blockquote>\n\n\n\n<blockquote class=\"wp-block-quote is-style-plain is-layout-flow wp-block-quote-is-layout-flow is-style-plain--1\">\n<p><\/p>\n<\/blockquote>\n\n\n\n<p><em>(the following paragraph is part of the DETECTA manual).<\/em><\/p>\n\n\n\n<p><strong>Groupthink: The Enigma of Radio Waves and Pulsars (1967)<\/strong> Occurs when the desire for harmony or conformity in a team results in irrational decision-making. <\/p>\n\n\n\n<p><\/p>\n\n\n\n<p>In 1967, astrophysicist Jocelyn Bell detected a strange radio signal that blinked with perfect mathematical precision from deep space. Nothing like it had ever been seen before. When she presented the finding to her team of supervisors at Cambridge, a fascinating phenomenon of groupthink emerged: because the signal was so regular, the entire group decided it had to be human interference. For weeks, the team convinced themselves it wasn&#8217;t worth looking for a new natural explanation because &#8220;everyone knew&#8221; stars didn&#8217;t blink like that. Group pressure caused scientific data suggesting a new class of star to be ignored. Only when Bell detected a second signal in a totally different part of the sky did the groupthink bubble burst, allowing the discovery of pulsars.<\/p>\n\n\n\n<p>I always like to add a song that is somehow related to the post. Unfortunately, my knowledge of Israeli music is very limited.<\/p>\n\n\n\n<p>However, there is a song I love; an amazing theme from the Yemenite Jewish tradition.<a href=\"https:\/\/youtu.be\/ZRnzTTYk7_Q?si=9DrWMBZXbaLADRYM\"> Ofra Haza\u2019s cover i<\/a>s my favorite, but in this case, I think this more delicate version is more fitting.<\/p>\n\n\n\n<figure class=\"wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"Im Ninalu - Oshrat Haim | \u05d0\u05dd \u05e0\u05e0\u05e2\u05dc\u05d5 - \u05d0\u05d5\u05e9\u05e8\u05ea \u05d7\u05d9\u05d9\u05dd\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/ZXFgREyxip8?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>The text explores the concept of the &#8216;Tenth Man Rule&#8217; from Israeli Intelligence, which encourages diverse viewpoints to combat groupthink. It references J. Kuperwasser&#8217;s insights on the &#8216;Devil\u2019s Advocate&#8217; role in fostering critical thinking and resilience within organisations. Additionally, it highlights the 1967 groupthink example with Jocelyn Bell&#8217;s pulsar discovery.<\/p>\n","protected":false},"author":1,"featured_media":3290,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"advanced_seo_description":"","jetpack_seo_html_title":"","jetpack_seo_noindex":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[367,4],"tags":[],"class_list":["post-3288","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-maintenance","category-psicologia"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/www.jorgebalaguer.com\/blog\/wp-content\/uploads\/2026\/04\/image.png","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/posts\/3288","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/comments?post=3288"}],"version-history":[{"count":5,"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/posts\/3288\/revisions"}],"predecessor-version":[{"id":3294,"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/posts\/3288\/revisions\/3294"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/media\/3290"}],"wp:attachment":[{"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/media?parent=3288"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/categories?post=3288"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jorgebalaguer.com\/blog\/wp-json\/wp\/v2\/tags?post=3288"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}