James E. Dougherty and Robert L. Pfaltzgraff, Jr, “Contending Theories of International Relations" (New York: Longman, 2001 for the fifth edition) is very well regarded and often shows up on graduate students' reading lists. It provides a solid overview of the field.
Martin Hollis; Steve Smith, (1991), Explaining and understanding International Relations, CUP. There is an overview about the growth of the discipline and how the theories reflect the time in which they were made. Also lots of literature for further reading given. A kind of goldmine that is also written very well. While this book provides an excellent grounding in the meta-theoretical debate about critical approaches versus the "positivist" approach, it is not really an introduction to IR theory per se.
[A note: Hollis has disappeared from the radar screen -the "explanation side" of the argument- but Smith -the understanding side- became the 2003-04 President of the ISA (International Studies Association). Is this a sign that positivists lost the battle? Not really. The ISA is a diverse association that encompasses many disciplines and welcomes many different views. But even a quick glance at the main journal in the field, International Organization, shows that positivists still have "the upper hand.")
Also see: Ken Booth, Steve Smith (eds.), (1997), International Relations Theory Today, Polity Press. Articles by most promising scholars in the field. Also critical approaches to IR. In the same vein, see the chapter by Ole Waever, “Figures on international thought: introducing persons instead of paradigms,” in Iver B. Neumann and Ole Waever, The Future of International Relations: Masters in the Making? (Routledge, 1997). The rest of the book is so-so, but that chapter is excellent.
International Relations (IR) and Theory - Some Analysis
IR has evolved through various political and normative concerns. The movements within the discipline are marked by great debates which concerned themselves with a number of goals. The first great debate was one preoccupied with the ontological bases of IR. This involved Realists' and Idealists' competing conceptions of the subjects of IR. The second great debate was between traditionalists and behaviouralists, and focussed on the methods that would be employed to acquire knowledge. The third great debate, also known as the inter-paradigm debate was between Realism, Liberalism and Critical Perspectives. This debate concerned itself with the epistemological considerations of IR and resulted in a synthesis of neo-realism and neo-liberalism. Following this, we have entered a fourth debate between positivists and post-positivists. Here, the assumptions of the positivist approaches are questioned by post-positivists and concomitantly, the relevance of post-positivist approaches to practice, is questioned by positivists. Recently, this fourth debate has lost momentum, as scholars increasingly focus on "middle-range theory" and increasingly accept the positivist epistemology (witness Wendt's "I am a positivist" remark in his Social Thoery of International Politics ).
The relationship between IR theory and state policy-making is a continuous one. In other words, there is not a distinct separation between the theory and practice of international relations (of course this would depend on the theoretical stance which one adopts). The most clear illustration of this is seen in the ways in which the US has dealt with terror in the last year. Hedley Bull's outline of Realism can be used to frame the reactions to the events of September 11; He indicates that for a Realist, the state is the most significant actor. Following from this, we can understand why the mechanisms for addressing non-state actors were not present in the US response. The US reaction involved implicating states in terror by claiming that states harbour terrorists and, in effect, they should be held accountable. Following this, Afghanistan was attacked.
With the state as the most significant actor, the referent of security is generally viewed as the state – the accompanying assumption is that the state is the protectorate of its people. Another reaction to the events of September 11 was the rekindling of the National Missile Defence project which seemed rather counterintuitive at the time. However, within a Realist framework, this seems to represent a reasonable response: the state is threatened – every step must be taken to protect the state. If we acknowledge these associations between Realist theory and US policy then we can effectively claim that theory and policy are intimately connected.
For a Poststructural Analysis see James Der Derian's writings:
On Diplomacy; Antidiplomacy: Spies, Speed, Terror and War; Virtuous War
The field is dominated by two large currents: liberalism (in the British sense) and realism. Other theories, like dependency, marxism, and else, are also present, but their appeal is more limited, as a survey of the main IR/political science journals would quickly reveal. Constructivism has become more "mainstream" in the last decade, but more research is needed before it gets the same recognition as realism and liberalism. One notable effort in the subfield of security studies is Katzenstein, ed., "The Culture of National Security." One is still awaiting the same for International Political Economy... The field may be diverse, but following 9/11, it is a sure bet that realism will make a comeback , making the above textbooks rather obsolete. Watch it in the pages of the journals APSR, ISQ, and of course, International Security and Security Studies.
Who are the main authors is a recurring question from undergrads --as well as grads. In no particular order, Hans Morgenthau, Kenneth Waltz, E.H. Carr, Robert Gilpin, Stephen Van Evera and John Mearsheimer are key authors for realism. Norman Angell, Karl Deutsch and John Ruggie (later associated to constructivism), Joseph Nye, Robert Keohane, Michael Doyle, and Lisa Martin are the main authors for liberalism, loosely defined. Other major authors include Alexander Wendt, Immanuel Wallerstein, and classics such as Hobbes, Machiavelli, Thucydides, Kant, Marx and Lenin. A quantitative branch of IR theory has specialized in quantitative analysis. This subfield is more oriented towards correlations than theorizing, but one should not neglect the contributions to the advancement of science made by people like Bruce Russett, A.F.K. Organski, Michael Brecher, and David Singer.