My own work has been part of this rationalist research program and I am highly committed to a modest form of rational-choice theory. Hence I wish to begin this commentary by indicating what that commitment means-and doesnt mean-to me Defining rationality involves very difficult issues of information. Rationality could be defined in such that the proposition of rational choice is irrefutable principle. If rationality simply means that a person does what he most prefers, a madman is perfectly rational. Perhaps he prefers to mutilate himself or to destroy those he loves On this basis, Hitler would have had to be judged rational-evil, but rational --when he ordered the Holocaust. But if all behavior is by definition rational, the concept of rationality"becomes meaningless. However, rationality need not be a meaningless concept, because a key condition for rationality involves the agents beliefs. Jon Elster offers a definition of what might be called"pure rationality, which emphasizes beliefs: An action, to be rational, must be the final result of three optimal decisions. First, it must be the best means of realizing an individual's desires, given his beliefs. Next, these beliefs must themselves be optimal given the information available to him. Finally, the person must collect an optimal amount of evidence -neither too much nor too little Of course, this definition of rationality turns it into an ideal type. No action is ever,in this definition, perfectly rational. But we can certainly make judgments about whether the behavior of particular agents approximates rationality or whether, like Hitler's, it flunks the informational tests. Hitler's beliefs about non-Aryans were wildly distorted, even given the information available to him. And he by no means searched analysis as inapplicable at least to some aspects of his behavior View rational-choice thoroughly for evidence. Hence we can judge him irrational and When I say that an actor behaves strategically, I do not mean that she behaves perfectly according to the rationalist ideal-type. To characterize behavior as strategic however, does have six implications: 1)that the agent makes choices in anticipation of the likely choices and reactions of others; 2)that she is concerned about the consequences of her actions; 3)that she orders her preferences in a broadly consistent fashion, so that her preferences are relatively stable across time and across issues; 4) that she selects means that she believes will achieve better rather than worse anticipated consequences in terms of her own ordered preferences; 5) that her beliefs are reasonable in view of available information; and 6) that she has searched for information that is relevant to the attainment of her objectives Strategic action is a matter of degree-we can act more or less strategically. Rationality is an ideal type, which is useful as a baseline for judging behavior as more or ss strategic. The assumption of rationality is also useful for creating formal models but is important to recognize that these are not models of actual behavior, but of ideal- typical behavior. Another way to express this point is to say that these models do not Jon Elster, Nuts and Bolts for the Social Sciences( Cambridge: 1989), p. 302 My own work has been part of this rationalist research program and I am highly committed to a modest form of rational-choice theory. Hence I wish to begin this commentary by indicating what that commitment means – and doesn’t mean – to me. Defining rationality involves very difficult issues of information. Rationality could be defined in such a way that the proposition of rational choice is irrefutable in principle. If rationality simply means that a person does what he most prefers, a madman is perfectly rational. Perhaps he prefers to mutiliate himself or to destroy those he loves. On this basis, Hitler would have had to be judged rational – evil, but rational -- when he ordered the Holocaust. But if all behavior is by definition rational, the concept of “rationality” becomes meaningless. However, rationality need not be a meaningless concept, because a key condition for rationality involves the agent’s beliefs. Jon Elster offers a definition of what might be called “pure rationality,” which emphasizes beliefs: “An action, to be rational, must be the final result of three optimal decisions. First, it must be the best means of realizing an individual’s desires, given his beliefs. Next, these beliefs must themselves be optimal, given the information available to him. Finally, the person must collect an optimal amount of evidence – neither too much nor too little.”6 Of course, this definition of rationality turns it into an ideal type. No action is ever, in this definition, perfectly rational. But we can certainly make judgments about whether the behavior of particular agents approximates rationality or whether, like Hitler’s, it flunks the informational tests. Hitler’s beliefs about non-Aryans were wildly distorted, even given the information available to him. And he by no means searched thoroughly for evidence. Hence we can judge him irrational and view rational-choice analysis as inapplicable at least to some aspects of his behavior. When I say that an actor behaves strategically, I do not mean that she behaves perfectly according to the rationalist ideal-type. To characterize behavior as strategic, however, does have six implications: 1) that the agent makes choices in anticipation of the likely choices and reactions of others; 2) that she is concerned about the consequences of her actions; 3) that she orders her preferences in a broadly consistent fashion, so that her preferences are relatively stable across time and across issues; 4) that she selects means that she believes will achieve better rather than worse anticipated consequences in terms of her own ordered preferences; 5) that her beliefs are reasonable in view of available information; and 6) that she has searched for information that is relevant to the attainment of her objectives. Strategic action is a matter of degree – we can act more or less strategically. Rationality is an ideal type, which is useful as a baseline for judging behavior as more or less strategic. The assumption of rationality is also useful for creating formal models – but is important to recognize that these are not models of actual behavior, but of ideal￾typical behavior. Another way to express this point is to say that these models do not 6 Jon Elster, Nuts and Bolts for the Social Sciences (Cambridge: 1989), p. 30