Über die Autorin bzw. den Autor

Stephen Peter Rosen is a political scientist and Beton Michael Kaneb Professor of National Security and Military Affairs at Harvard University

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"This is a lucid, beautifully-written, informative and provocative book. It presents the modern science of choice and decision persuasively."--Thomas Schelling, University of Maryland

"War and Human Nature holds the potential to open an entirely new area of insight into war. It will provide a new way of thinking about the collapse of armies, the choices and behaviors of tyrants, and the way in which differing elite selection mechanisms may wittingly or otherwise lead to individuals with differing cognitive profiles ending up in office. The use of the cognitive science literature is novel and provides insight into an area of research social scientists typically ignore."--Allan C. Stam, Dartmouth College

"A thought-provoking, timely synthesis of political decision-making in light of recent progress in neurobiology, psychology and behavioral biology. Rosen explores an intriguing new formulation of biologically-motivated political science."--Michael L. Platt, Duke University

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War and Human Nature

Princeton University Press

Chapter One

THE GREEK HISTORIAN Thucydides analyzed decisions about war and peace over two thousand years ago. People, he argued, were motivated by calculations of self-interest, but other factors mattered as well, factors like fear and honor, that were not quite the same as self-interest. If you asked a social scientist today what drives decisions about war, you would get the answer that people make decisions about the use of organized violence more or less in the same way that economists say people make economic decisions, that is, in a coherent, stable, and efficient manner. This book is an exploration of a more complicated understanding of human decision making. It does not reject the explanation of decision making offered by the economists, which is often a useful analytical tool. It does, however, argue that processes other than conscious calculation play a role in human decision making along with conscious calculation. Emotion, stress, and hormones such as testosterone are important players in human decision making. By understanding the role of these other cognitive mechanisms, we can often better specify the limits within which conscious, rational calculations are performed. We can also specify the ways in which human decision making may change as our bodily states change. This helps us understand why the behavior of decision makers may not be stable over time, though their behavior could be understood as rational at any one moment. These other nonconscious factors can enable rational decision making, but they do lead to decisions that we would not understand or predict if we did not take those factors into account.

The evidence for this argument comes from many sources. It includes data from college students who participate in psychological experiments. It includes data from people receiving medical treatment for mental disorders. In such cases, we must be very careful not to extrapolate directly from these findings to the behavior of leaders in the real world, who, after all, tend not to be college sophomores or brain-damaged. Yet those experiments and the data from the treatment of patients can help us understand the operations of the human mind. What happens when certain portions of the brain responsible for understanding human emotion, for example, are disabled? By answering this question, we can begin to see how the behavior of people who have not experienced brain damage may be affected by the operation of those portions of the brain. By understanding why nineteen-year-old men are different from average politicians, most noticeably with regard to their testosterone levels, we can begin to see how variations in testosterone levels can affect human decision making.

There will be a natural tendency to see the operation of these nonconscious cognitive mechanisms as producing "bad" decisions, while conscious calculations produce "good" decisions. While natural, this would be a mistake. To repeat, the nonconscious mechanisms often function in ways that make rational choice possible in complex settings. These non-conscious mechanisms exist because they played a positive role in human evolutionary history. For example, they make possible rapid decisions when there are severe limits on the amount of time available for deliberation. But they may lead to decisions that differ from what standard economic models would predict. As Daniel Kahneman and Amos Tversky demonstrated, people may overgeneralize from limited observations, impute characteristics to people on the assumption that they are representative of a group, and take more risks to avoid losses than to achieve gains. This book will explore the ways in which emotional memories may affect rational decisions, how stress and distress may lead to depression and defeat, and how testosterone may affect the impulse to punish perceived challengers. All of these phenomenan could be judged, after the fact, to be "good" or "bad." The concern of this book, however, will simply be to understand how and why the decisions were made, without judging the outcomes. This issue will be explored, in particular, in chapter 2. The argument of the book is, in its essence, reasonably simple. It includes biological issues, but it is not a biological determinist argument. Human beings have several mechanisms inside them that play a role in decision making. These multiple mechanisms exist as a result of our biological inheritance. Human beings are not exactly alike, and in a population of people there will be variations in their biological inheritance. These variations affect the mechanisms involved in making decisions about social problems, including war. These biological factors and the way in which they vary from person to person can affect the political behavior of states. But there is a social or organizational component to the argument as well. The behavior of states will depend on the nature of the social institutions that empower or weaken the influence of individuals with certain inherited ways of making decisions. The impact of the biological mechanisms analyzed in this book depends on the social settings within which people make decisions, social settings that are, in part, the result of human choice. In short, this book tries to make the case that there is a biological argument that Thucydides was right, that fear and honor play a role in human politics along with calculations of interest, but also that the other issues he analyzed, such as the nature of the political systems present in the ancient Greek world, matter as well.

Making that case takes some effort. This book uses the current scientific understanding of human nature, along with an understanding of social institutions, to explain human cognition as it is relevant to the issues of war and peace. Since the terms "human nature" and "cognition" are used in a variety of ways, they should be defined. In this book, cognition will mean the way in which information is selected, stored, recalled, and used, consciously or unconsciously, for decision making. Human nature will refer to the aspects of human cognition that are affected by biological inheritance, as those inherited factors are shaped by human interaction with the environment. This book argues that the two are linked. There are inherited parts of the brain and the endocrine system that function along with the parts of the brain that do perform conscious calculations. They affect rational calculation, and can facilitate rational calculation, but they can also push us toward decisions that are different from the ones we would make on the basis of conscious calculation alone. Indeed, it will be shown that conscious calculations by themselves may be insufficient to lead people to a decision, and other factors are important because they make possible rational choices in complex environments. Yet those other factors do complicate our internal decision-making processes. It is because of the coexistence of these other mechanisms, along with conscious calculation, that Thomas Schelling was correct when he stated that human behavior must be understood as the interaction between at least two conflicting selves within each person.

The rest of this book is an elaboration of these ideas.

It helps to begin by looking at human nature and cognition in general, or the biologically affected ways of processing information that most people have...