The term “adversary problem-solving” is normally used to describe situations in which two or more opponents are trying to achieve some goal (Gilhooly, 1989; Nilsson, 1971). The passive or defensive side tries to prevent the active or attacking side from doing so. This kind of problemsolving usually appears in situations of human conflict and competition. Adversary situations are common in games and sports, but they may also occur in many fields of practical life. It is not only chess and tennis that constitute adversary situations; business life, politics, courtrooms, diplomacy, and military actions also provoke them (Amsel, Langer & Loutzenhisher, 1991; Voss, Wolfe, Lawrence, & Engle, 1991; Wagner, 1991). Even some apparently one-party situations such as science or medicine may sometimes be interpreted as a game against nature, and thus they may share psychological properties with genuine adversary situations (Simon 1977). Hintikka’s game-theoretical semantics serves as a very non-standard example of an adversary interpretation of an apparently very clearly non-adversary situation, i.e. the determination of sentence meanings (e.g. Hintikka & Kulas, 1983).