전략적 선택모델: 게임이론 동시적 게임 죄수의 딜레마 비겁자 게임 전개형(순차적) 게임 농부와 호랑이 오사카 성의 해자 전략적 선택모델: 게임이론 동시적 게임 죄수의 딜레마 비겁자 게임 전개형(순차적) 게임 농부와 호랑이 오사카 성의 해자 전략적 선택 영향요인 Brigid Starkey, Mark Boyer, and Jonathan Wilkenfeld, International Negotiation in a Complex World, 3rd ed. (Rowman & Littlefield, 2010), 제5장 참조

게임이론: 합리적 선택모델 Negotiation models based in game theory illustrate the array of choices one actor has at any given moment, as well as how outcomes are dependent on the choices both or all of the negotiating parties make. Emphasis is on the role of ends (goals) in determining outcomes Models of rational choice: Negotiators are viewed as rational decision makers with known alternatives who make choices guided by their calculation of which option will maximize their ends or “gains”, frequently described a ‘payoffs’ Rational choice in situations involving interdependence

게임이론: 합리적 선택모델 기본개념과 분석틀 Simultaneous Game (동시적 게임) Players must make their decisions at the same time Decisions one player makes are affected by the possible decisions others will make Sequential Game (순차적 게임) Each player makes a decision at a different point in time Model action-reaction processes to reveal the ways international actors react to problems and other stimuli from international affairs Demonstrate how those reactions lead to other reactions by even more actors throughout the system

게임이론: 합리적 선택모델 Payoffs (수익, 보수) Numbers which represent the motivations of players. Payoffs may represent profit, quantity, or “utility” Strategy (전략) Strategy: “the set of choices that each player will select in the face of all possible contingencies” 주어진 목적을 달성하기 위해 행위자가 상대방의 반응을 고려해서 선택하는 일련의 행동계획 Dominant strategy (지배전략) A strategy is dominant if, regardless of what any other players do, the strategy earns a player a larger payoff than any other

게임이론: 합리적 선택모델 Outcomes (결과) Nash equilibrium (내쉬균형) A set of strategies, one for each player, such that no player has incentive to unilaterally change her action. 상대방의 행동을 염두에 두고 자신이 할 수 있는 최선의 행동을 할 때에 나타나는 결과 Pareto Optimal Outcome (파레토 최적결과) There is no other outcome that is an improvement for at least one of the players without making someone else worse off 상대방의 이익이나 효용을 감소시키지 않고서는 자신의 이익이나 효용이 증가하지 않게 되는 상태

동시적 게임: 죄수의 딜레마 Preference ordering DC ＞CC ＞DD＞ CD (Cooperate) (Defect) (Cooperate) Preference ordering DC ＞CC ＞DD＞ CD (Defect)

동시적 게임: 죄수의 딜레마 Interpretations Dominant Strategy Nash Equilibrium: The equilibrium is not necessarily the best payoffs (e.g.) A Climate Change Dilemma Dilemma: while cooperation is collectively rational, defection is individually rational

동시적 게임: 죄수의 딜레마 Interpretations - cont’d How to cooperate with each other? A repeated version of the PD game A “tit-for-tat strategy”(맞대응전략) Axelrod, Evolution of Cooperation (1984) Involves starting out the game as cooperative and then punishing one’s opponent whenever she fails to cooperate If you move first, cooperate If you move second, reciprocate in kind

동시적 게임: 비겁자 게임 Preference ordering DC ＞CC＞CD＞ DD (Defect) (Cooperate)

동시적 게임: 비겁자 게임 Interpretations A type of Brinkmanship Dominant Strategy Nash Equilibrium Equilibrium point #1 Player 1 – swerve Player 2 – do not swerve Equilibrium point #2 Player 1 – do not swerve Player 2 – swerve

동시적 게임: 비겁자 게임 사례 1962 Cuban Missile Crisis North Korean Crises USSR Back down Proceed (-1,-1) (2,4) (4,2) (-30,-30) US In his speech of October 22, 1962, President Kennedy declared that “our unswerving objective” is to get Soviet missiles removed from Cuba. 1962 Cuban Missile Crisis N. Korea Back down Proceed (-1,-1) (2,4) (4,2) (-30,-30) US & Allies North Korean Crises

순차적 게임 Sequential games are those in which players make moves at different times or in turn. Players who move later in the game have additional information about the actions of other players. Players who move first can often influence the game. (e.g.) Arms Race As both sides respond to the military threats their counterpart poses, neither side become more secure over the long term, and both sides engage in a conflict spiral Security Dilemma Sequential choices can be depicted in a decision tree

순차적 게임: 호랑이와 농부 호랑이의 선호도 DC> CC> DD > CD 농부의 선호도 DC> DD> CC > CD *순차적 게임사례는 윤홍근, 박상현,『협상게임: 이론과 실행전략』(인간사랑, 2010), 제2장 참조

순차적 게임: 호랑이와 농부

기대효용이론: 호랑이와 농부

기대효용이론: 호랑이와 농부

순차적 게임: 호랑이와 농부

순차적 게임: 오사카성과 해지 히데요리 선호도 DC> CC> DD > CD 이에야스 선호도 CD> DD> CC > DC

북한 핵 위기 결정나무(decision tree) 순차적 게임 북한 핵 위기 결정나무(decision tree)

순차적 게임: 역행귀납법 (Backward Induction) “look ahead and reason back” approach to strategy The process of reasoning backwards in time, from the end of a problem or situation, to determine a sequence of optimal actions Backward Induction One determines the optimal strategy of the player who makes the last move of the game The optimal action of the next-to-last moving player is determined taking the last player's action as given The process continues in this way backwards in time until all players' actions have been determined Example of Figure 5.3

전략적 선택: 영향요인 Defining Interests Negotiators and policy makers are assumed to make decisions on the basis of the interests and values held by their constituents A dichotomy when conceptualizing interests: A narrow view of national (or actor) interest A broader, or enlightened, view of national interest Narrow definition of interests When decision makers and negotiators are most concerned with how a particular situation affects political and economic forces at home Conceptions of narrow interests explain why the equilibrium outcomes in the PD game are negative or suboptimal ones

전략적 선택: 영향요인 Defining Interests – cont’d Broader definition of interests Factors Ways actors identify with others involved in the same games Constructivism: Countries with long-term relationships will have higher levels of common interest when confronted with the need for collective international problem-solving Positively influenced by the creation of international institutions and the development of international norms Time frame that is considered to be important to decision makers and negotiators Distinctions between short-term and long-term perspectives are constant factors in international environmental negotiations

전략적 선택: 영향요인 Complexities of the Negotiation Actors and issues are added to the negotiations, or coalitions form Additional issues are linked to an original issue A lack of domestic or constituent consensus about the negotiation goals and/or approach The negotiators must check back with superiors The goals and preferences of the negotiation team change due to domestic or international pressure Negotiations involve a mixture of conflictual and cooperative motives or goals Information about other parties’ goals and preferences is lacking A crisis, thereby increasing the pressure on negotiators

전략적 선택: 영향요인 Long-term Relationships “Shadow of the future”: awareness of the impact of repeated play Where the expectation of repeated play is high, the likelihood of cooperative moves becomes greater (e.g.) This long-term commitment to free trade on the part of GATT participants pushed the negotiators to create the World Trade Organization (WTO) Impact of “tit-for-tat strategies”: Awareness of larger long-term relationship can produce an element of fear Threat that a negotiating partner might reciprocate a squeal payoff sometime in the future can bolster the search for cooperative outcomes on the part of all involved