War! What Is It Good For? by Ian Morris is alone among thousands of books on war written in recent decades—not because it celebrates or justifies war, but because it refuses to simplify it. Morris is not pro-war. He is a historian trying to understand what war has actually done to human societies over 15,000 years.
His central argument: over the long sweep of history, war has often made societies safer, larger, and more organized, even as it inflicted immense suffering. Early human societies were extraordinarily violent, with high rates of death from raids and small-scale conflict. As war forced the creation of larger states and stronger governments, those same structures reduced internal violence and enabled economic growth. In Morris’s formulation, war is history’s great paradox: destructive in the short term, but sometimes stabilizing in the long term.
This is not a comforting thesis, and Morris does not present it as one. He is clear that war is horrific and that modern weapons could destroy everything humanity has built. But he insists that if we want to understand how we arrived at a relatively less violent world—where fewer people die violently today than in premodern societies—we must confront the role war has played in creating large, internally peaceful states.
The strength of the book lies in its scope. Morris moves from prehistoric tribal warfare to modern industrial conflict, drawing on archaeology, history, and social science. He shows how war drives state formation, taxation systems, infrastructure, and even ideas about citizenship. In this sense, war is not just a series of battles; it is a force that shapes institutions and social order.
Yet this sweeping perspective can also be misread—especially in today’s political climate. Morris helps clarify an essential distinction that is often blurred: the difference between wars of choice and wars of necessity.
Wars of necessity—such as Russian invasion of Ukraine—fit more easily into Morris’s historical pattern. When a society defends itself against invasion, it mobilizes, strengthens institutions, and often deepens internal cohesion. These are the kinds of wars that historically have contributed to state-building and, paradoxically, to longer-term stability.
Wars of choice are different. A hypothetical example—such as a powerful nation attacking another without provocation—falls outside the logic Morris describes. These wars do not arise from existential threats or defensive necessity; they are discretionary. Historically, such conflicts often weaken institutions, drain resources, and create instability rather than order. Morris’s argument does not justify them. If anything, it exposes their danger: they attempt to harness the state-building effects of war without the unifying force of genuine necessity.
This distinction matters. Morris’s book is not a moral defense of war but a historical analysis of its consequences. It challenges readers to hold two truths at once: war has been one of the primary engines of social development, and it remains one of humanity’s greatest sources of suffering.
In the end, War! What Is It Good For? forces readers into uncomfortable territory. It rejects both naïve pacifism and easy militarism. Instead, Morris offers a harder lesson: if we want a world with less war, we must first understand the role war has played in creating the world we live in.
Last month I wrote about three of Morris's books I read, including War! But the expanding war America started in the Middle East made me think War! should be separate from the others.
