{"id":74707,"date":"2026-03-24T18:10:41","date_gmt":"2026-03-24T16:10:41","guid":{"rendered":"https:\/\/www.uol.ac.cy\/?p=74707"},"modified":"2026-03-24T18:10:50","modified_gmt":"2026-03-24T16:10:50","slug":"the-private-solution-trap-in-collective-action-problems-across-34-nations","status":"publish","type":"post","link":"https:\/\/www.uol.ac.cy\/en\/the-private-solution-trap-in-collective-action-problems-across-34-nations\/","title":{"rendered":"The private solution trap in collective action problems across 34 nations"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><strong>Proceedings of the National Academy of Sciences (PNAS)<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Volume 123, Issue 12, March 2026<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Article:<\/strong>&nbsp;e2504632123<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Abstract<\/strong><br>Collective action problems emerge when individual incentives and group interests are misaligned, as in the case of climate change. Individuals involved in these problems are generally considered to have two options: contribute toward public solutions such as global warming mitigation or free ride. However, many collective action problems today involve a third option of investing in a \u201cprivate solution\u201d such as local adaptation. The availability of this third option can lead to a private solution trap whereby private solutions are adopted, collectively optimal public solutions are not provided, and existing inequalities are exacerbated. We investigated the private solution trap with a collective action game featuring private and public solutions, wealth inequality determined by luck or merit, and participants from 34 countries. We found that the joint existence of private solutions and wealth inequality had a consistent effect across countries: Participants given a higher endowment adopted private solutions almost twice as often as those given a lower endowment, regardless of whether it was determined by luck or merit, and contributed proportionally less toward public solutions. Wealth inequality increased in every country and those given lower endowments were often left unprotected as public solutions were not provided. Across countries, cultural values of hierarchy and harmony were associated with preferences for private and public solutions, respectively. We also identified two universal pathways toward public solution provision: early contributions and conditional cooperation. Our findings highlight the ubiquity of the private solution trap, its cultural underpinnings, and its potential consequences for global collective action problems.<\/p>\n\n\n\n<div class=\"wp-block-uagb-blockquote uagb-block-1d5a257a uagb-blockquote__skin-border uagb-blockquote__stack-img-none\"><blockquote class=\"uagb-blockquote\"><div class=\"uagb-blockquote__content\"><strong>By:<\/strong><\/div><footer><div class=\"uagb-blockquote__author-wrap uagb-blockquote__author-at-left\"><cite class=\"uagb-blockquote__author\">\u00a0Eugene Malthouse, Charlie Pilgrim, Daniel Sgroi, Nobuyuki Hanaki, Thomas Hills, et al.<\/cite><\/div><\/footer><\/blockquote><\/div>\n\n\n\n<div style=\"height:40px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<div class=\"wp-block-uagb-buttons uagb-buttons__outer-wrap uagb-btn__default-btn uagb-btn-tablet__default-btn uagb-btn-mobile__default-btn uagb-block-b046ead0\"><div class=\"uagb-buttons__wrap uagb-buttons-layout-wrap \">\n<div class=\"wp-block-uagb-buttons-child uagb-buttons__outer-wrap uagb-block-51d8dd04 wp-block-button\"><div class=\"uagb-button__wrapper\"><a class=\"uagb-buttons-repeater wp-block-button__link\" aria-label=\"\" href=\"https:\/\/eur02.safelinks.protection.outlook.com\/?url=https%3A%2F%2Fwww.pnas.org%2Fdoi%2F10.1073%2Fpnas.2504632123&amp;data=05%7C02%7Cp.efstathiou%40uol.ac.cy%7C9c60270852184a61051608de89a63501%7Cb5e1322f342e4a7ebb1e78d50e9fd700%7C0%7C0%7C639099544090208825%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&amp;sdata=J4VoFKsYiTDVzWiTOVmilS3ceo0TX%2BlF%2B5HAL4znGrs%3D&amp;reserved=0\" rel=\"nofollow noopener\" target=\"_blank\" role=\"button\"><div class=\"uagb-button__link\">learn more<\/div><span class=\"uagb-button__icon uagb-button__icon-position-after\"><svg xmlns=\"https:\/\/www.w3.org\/2000\/svg\" viewBox=\"0 0 448 512\" aria-hidden=\"true\" focussable=\"false\"><path d=\"M438.6 278.6l-160 160C272.4 444.9 264.2 448 256 448s-16.38-3.125-22.62-9.375c-12.5-12.5-12.5-32.75 0-45.25L338.8 288H32C14.33 288 .0016 273.7 .0016 256S14.33 224 32 224h306.8l-105.4-105.4c-12.5-12.5-12.5-32.75 0-45.25s32.75-12.5 45.25 0l160 160C451.1 245.9 451.1 266.1 438.6 278.6z\"><\/path><\/svg><\/span><\/a><\/div><\/div>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"<p>Proceedings of the National Academy of Sciences (PNAS) Volume 123, Issue 12, March 2026 Article:&nbsp;e2504632123 AbstractCollective action problems emerge when individual incentives and group interests are misaligned, as in the case of climate change. Individuals involved in these problems are generally considered to have two options: contribute toward public solutions such as global warming mitigation [&hellip;]<\/p>\n","protected":false},"author":17,"featured_media":74710,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_uag_custom_page_level_css":"","site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[123],"tags":[],"publication_author":[186],"publication_year":[222],"class_list":["post-74707","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-latest-publications","publication_author-nobuyuki-hanaki","publication_year-222"],"acf":[],"uagb_featured_image_src":{"full":["https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026.jpg",1200,628,false],"thumbnail":["https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026-150x150.jpg",150,150,true],"medium":["https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026-300x157.jpg",300,157,true],"medium_large":["https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026-768x402.jpg",768,402,true],"large":["https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026-1024x536.jpg",1024,536,true],"1536x1536":["https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026.jpg",1200,628,false],"2048x2048":["https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026.jpg",1200,628,false],"trp-custom-language-flag":["https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026-18x9.jpg",18,9,true]},"uagb_author_info":{"display_name":"p.efstathiou@uol.ac.cy","author_link":"https:\/\/www.uol.ac.cy\/en\/author\/p-efstathiouuol-ac-cy\/"},"uagb_comment_info":0,"uagb_excerpt":"Proceedings of the National Academy of Sciences (PNAS) Volume 123, Issue 12, March 2026 Article:&nbsp;e2504632123 AbstractCollective action problems emerge when individual incentives and group interests are misaligned, as in the case of climate change. Individuals involved in these problems are generally considered to have two options: contribute toward public solutions such as global warming mitigation&hellip;","jetpack_shortlink":"https:\/\/wp.me\/peAODB-jqX","publishpress_future_workflow_manual_trigger":{"enabledWorkflows":[]},"jetpack_featured_media_url":"https:\/\/www.uol.ac.cy\/wp-content\/uploads\/2026\/03\/hanaki_news-cover_march2026.jpg","_links":{"self":[{"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/posts\/74707","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/users\/17"}],"replies":[{"embeddable":true,"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/comments?post=74707"}],"version-history":[{"count":0,"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/posts\/74707\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/media\/74710"}],"wp:attachment":[{"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/media?parent=74707"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/categories?post=74707"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/tags?post=74707"},{"taxonomy":"publication_author","embeddable":true,"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/publication_author?post=74707"},{"taxonomy":"publication_year","embeddable":true,"href":"https:\/\/www.uol.ac.cy\/en\/wp-json\/wp\/v2\/publication_year?post=74707"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}