Emergence and collapse of peace with friend selection strategies

Yutaka Nakai, Masayoshi Muto

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


A society consisting of agents who can freely choose to attack or not to attack others inevitably evolves into a battling society (a 'war of all against all'). We investigated whether strategies based on C. Schmitt's concept of the political, the distinction of a friend and an enemy, lead to the emergence and collapse of social order. Especially, we propose 'friend selection strategies' (FSSs), one of which we called the 'us-TFT' (tit for tat) strategy, which requires an agent to regard one who did not attack him or his 'friends' as a 'friend'. We carried out evolutionary simulations on an artificial society consisting of FSS agents. As a result, we found that the us-TFT results in a peaceful society with the emergence of an us-TFT community. In addition, we found that the collapse of a peaceful society is triggered by another FSS strategy called a 'coward'.

Original languageEnglish
Issue number3
Publication statusPublished - 2008 Jun
Externally publishedYes


  • A Friend and an Enemy
  • Carl Schmitt
  • Community
  • Coward
  • Evolutionary Simulation
  • Tit for Tat

ASJC Scopus subject areas

  • Computer Science (miscellaneous)
  • Social Sciences(all)


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