John Mearsheimer:

The book comes with 150 pages of notes, and the notes alone are a treasure of information.

His theory clearly collides with the "liberal" or "idealist" view of history that is based on three assumptions: interdependent economies don't go to war against each other (Edward Mansfield's "Power, Trade and War", 1994; Thomas Friedman's "The Lexus and the Olive Tree", 1999; etc); democracies don't go to war against each other (Francis Fukuyama's "The End of History", 1992; Bruce Russett's "Grasping the Democratic Peace", 1993; John Owen's "Liberal Peace, Liberal War", 1997; etc); and international institutions prevent wars (e.g. Robert Keohane's "After Hegemony", 1984). The West has been promoting international trade, democracy and supranational institutions as vehicles to cement world peace. Liberal historians divide states in good and bad states, depending on their reasons for going to war. Mearsheimer thinks these are pointless exercises, and that there are no good or bad powers: there are just powers, and the logic of powers is the same regardless of their ideology.

Mearsheimer follows instead the "realist" view of history that had two main champions: Hans Morgenthau ("Politics among Nations", 1948) and Kenneth Waltz ("Theory of International Politics", 1979). The differences among the three are minimal but lead to wildly divergent conclusions. Morgenthau thought that multipolar systems were more peaceful than bipolar ones. Waltz and Mearsheimer think otherwise. Morgenthau thought that powers are fundamentally offensive because of human nature (hence his brand of realism is known as "human nature realism"), a view held before him by many, notably by Friederich Meinecke in "Machiavellism - The Doctrine of Raison d'Etat and Its Place in Modern History" (1924) and by Reinhold Niebuhr in "Moral Man and Immoral Society" (1932). Waltz and Mearsheimer think that powers are driven by a sort of survival instinct: the only way to feel secure is to be more powerful than the rivals. Waltz thinks that states are driven by the need to survive: the more anarchic the world, the more states fight for supremacy. Walts's States don't really want to fight and would rather not (hence Waltz's realism is known as "defensive realism"). Similar views were held by Jack Snyder in "Myths of Empire" (1991) and Robert Powell in "In the Shadow of Power" (1999). Mearsheimer instead thinks that states are inherently offensive: they seek hegemony, not status quo. Mearsheimer's "offensive realism" shares with "human nature realism" the conclusion that powers relentlessly seek power, no matter their regime and no matter what their rivals do. Mearsheimer thinks that the foreign policy of the USA has been schizophrenic: the public statements endorse the "liberal" view of history but the practical actions are driven by a "realist" view.

Mearsheimer's logic is impeccable: if survival is the main goal of a state and states are rational actors and states can never be certain about the intentions of other states, then states must seek to maximize their power and minimize the power of other states. "States are power maximizers". John Herz's "Idealist Internationalism and the Security Dilemma" (1950) discussed the inevitable effect of this logic: as a state increases its own security, it decreases the security of other states, inevitably provoking a rection from the other states, which in turn threatens its own security. This became known as the "security dilemma".

Scholars have been debating for decades which is the most important aspect of military power: the navy, the air force or the army. Mearsheimer believes that land power prevails because large bodies of power severely limit what can be done. Before World War I many believed that sea power was the key to imperial success. See for example Alfred Mahan's book "The Influence of Sea Power upon History" (1890). After World War I many believed that air power was the new key to imperial success. See for example Giulio Douhet's book "The Command of the Air" (1927). Mearsheimer doubts that a land invasion from the sea can be as efficient as a land invasion over land. Since Julian Corbett published his book "Some Principles of Maritime Strategy" (1911), many strategists have assumed that protecting the lines of communication and supply is much more difficult at sea than on land. And books such asRobert Pape's “Bombing to Win" (1996), which draws on almost 80 years of airpower history, have analyzed the limits of air bombing in winning a war. On the other hand books such as Edwin Pratt's "The Rise of Rail-Power in War and Conquest" (1915) have been studying how railroads improved the speed of land invasions.

While war is the main way in which states acquire power (although cost-benefit analysis does not always justify it), Mearsheimer several others: blackmail (the threat of force), bait and bleed (causing two rivals to engage in a protracted war), bloodletting, balancing and buck-passing. Powers not only aim to dominate but also try to prevent other powers from dominating. And of course powers try to achieve maximum share of the world's wealth. Appeasement never works because it is not a resolution of the conflict: it only postpones the inevitable.

Offensive realism is simply a theory of opportunistic foreign policy.

The book ends with a brief discussion of China, clearly the power that is trying to rival US power in the Pacific, and clearly the prime candidate to go to war against the USA at some point.

A corollary to Mersheimer's theory is that the specific leaders of a country (Winston Churchill, Adolf Hitler, Franklin Roosevelt, Josef Stalin, Obama, Putin, Xi, etc) don't matter that much: the fate of their nations is sealed by the inevitable will to power. Ditto for the culture of the nation and the ideology of the regime. Unfortunately, another corollary is that diplomacy is an illusion: the fate of nations prevails over any negotiation, and that fate is determined by the will to power. For the same reason he neglects cooperation as a strategic alternative to competition: in his view cooperation will never provide an absolute degree of security to the cooperating states and so it won't solve the problem.

The ultimate solution to the security dilemma would be a world government, i.e. the elimination of states. A less ideal but also effective solution is to have a superpower impose order, like the Romans and the Mongols did, and like the USA did in the West after World War II. A corollary is that he views multipolar systems as inherently dangerous: idealists who advocate a lessening of US power are indirectly increasing the chances of war. Multipolar systems are more war-prone than bipolar ones.

One problem with Mearsheimer's theory is that he is very much steeped in the technology of past centuries. There is little analysis of what cyberwarface, unmanned drones, and weapons of mass destruction can do. The theory is to steeped in the past, a past in which technology was wildly different.

The biggest liability of this book is that it has never stated what the difference is between a state (any state, no matter how small) and a "power". Is there any state that doesn't aim to maximize its security? Is there any state that doesn't aim to become a "power"?

Modern Europe (as well as Japan) seems to show that states are sensitive to the costs of security, or at least their public opinion is, and, if the state is democratic, that public opinion elects the leaders who enact their foreign policy. As more regions of the world become like Europe, one could hope that the cost of security becomes the preeminent factor in deciding foreign policy, and minimizing that cost will increase the willingness to accept security risks.