The business of serious thinking and writing about the world we live in never stops, not even during wartime. During World War II, three great works which fall under the term “PPE”—the study of modern philosophy, politics, and economics—were published while battles raged across the world. These works by the Austro-English philosopher Karl Popper, the Austrian economist Joseph Schumpeter, and his fellow Austrian economist Friedrich Hayek, remain relevant for all readers who seek to understand our world today.

By way of history, the formal study of Philosophy, Politics and Economics (PPE) as a degree program was first established at Oxford University in 1921 in the wake of the Great War. Balliol College at Oxford was a leader in establishing a program of “modern classics,” that is, more contemporary works of philosophy and political economy for Oxford graduates destined for the British Civil Service. The traditional Classics program was intended to provide a thorough education in the humanities focused on the histories and languages of ancient Greece and Rome. The new program was meant to provide undergraduate and graduate students with a deeper understanding of modern society, applying the analytical reason and ethics learned in their study of philosophy to the structures and interactions of modern political and economic systems.

There are two books that I think deserve honorable mentions in this post. The first is John Maynard Keynes, whose 1936 masterwork The General Theory of Employment, Interest and Money, through its concept of the state acting as a balancing mechanism through deficit spending during downturns in the business cycle of a capitalist economy, had a massive impact on theoretical economists and public policies by wartime and postwar governments around the world. The other work which impacted political scientists seeking to understand the motivations and actions of states within the international political system was written by Hans Morgenthau. His book Politics Among Nations, published in 1948 in the wake of World War II during the rise of the Cold War, firmly established him as one of the leaders of the realist school of foreign policy, with concepts of national interest and power at the center of explanations for how the world works.

While these works can be considered as part of the larger wartime era, however, they were not published during the years of active hostilities in Asia and Europe during the years 1937-1945. Therefore, the short list of three great works of philosophy, politics and economics (PPE) from World War II are:

Capitalism, Socialism and Democracy by Joseph Schumpeter

The Austrian economist Schumpeter was briefly the Minister of Finance in 1919 in the Republic of German Austria in the wake of the Great War. By 1932, he had permanently moved to the United States, teaching economics at Harvard University. Published in 1942, Capitalism, Socialism, and Democracy focused on the role of entrepreneurship and how it moved business cycles by a process which Schumpeter called “creative destruction.” He argued that social change had to be understood in terms of evolution, that economic history provided essential data from which change could be understood, but emphasized that entrepreneurs and innovation not only created new wealth and economies, but destroyed old, stable economies in the process of ascending to greater wealth. Schumpeter was clear that he was not an advocate, but also argued that capitalism would eventually collapse from within as the system of creative destruction wore itself out, and he believed it would eventually be replaced by socialism based upon a corporatist model (not from violent proletarian revolution that would establish a utopian order, as Marx predicted.)

During World War II, innovation occurred throughout American industry on an unprecedented scale that allowed the creation and mass production of weapons of incredible complexity and power, such as the B-29 Superfortress, and perhaps culminating with the Manhattan Project. In our modern world shaped by the undeniable influence of entrepreneurs such as Steve Jobs and Elon Musk, Schumpeter’s insights on how entrepreneurs initiate and shape social and economic change, through both the creation of new orders and destruction of existing systems are essential to understanding postwar history. Schumpeter claimed that of his three personal goals in life—to be the greatest economist in the world, the greatest horseman in Austria, and the greatest lover in Vienna—he achieved two of them, although he never identified which two before he passed away at age 66 in 1950.

The Road to Serfdom by Friedrich Hayek

A veteran who served as an aerial spotter for an Austro-Hungarian artillery unit in the Great War, Hayek earned two doctorates from the University of Vienna after the war and vowed to pursue an academic career in hopes of contributing to a better world and avoiding another war. After moving to the London School of Economics in 1931, Hayek refused to return to Austria after Hitler absorbed the country in the 1938 Anschluss. Written as Britain engaged Nazi Germany in the war he had hoped to avoid, Hayek published The Road to Serfdom in 1944 to warn that National Socialism, fascism, Stalinism, and socialism all grew from a common source: central economic planning by government, which of necessity elevated the state over individual decision makers in the marketplace and eventually resulted in tyranny.

Hayek was concerned that the increasing roles the state was playing in the economy in Britain and the United States would lead them to slowly abandon the classic liberal doctrine based upon individual rights that distinguished them. While Hayek recognized legitimate roles which the government should assume in the economy because free markets could not, such as legally banning fraud and enacting measures to maintain minimum level of security for the least fortunate, he was in the end most concerned about the survival of individual liberties. While Hayek focused mostly on the fascist governments in his arguments, his book’s impact increased in the postwar years as it held obvious implications and arguments for the western democracies in the long decades of the Cold War with the Soviet Union, ultimately selling over two million copies. Hayek would go on to teach at the University of Chicago after the war and shared the Nobel Prize in economics in 1974, and lived to see the fall of the Berlin Wall and dissolution of the Soviet Union before his death in 1992.

The Open Society and Its Enemies by Karl Popper

Written during the war while he was a professor at the University of New Zealand, Popper’s two-volume work published in 1945 traced the roots of totalitarian thought back to Plato in the first volume, and then analyzed the thought of nineteenth German thinkers George Wilhelm Friedrich Hegel and Karl Marx back to Aristotle in the second. Popper writes in favor of what he terms an “Open Society” or liberal democracy, which he argues is the best form of societal organization which can encompass change without the necessity of bloodshed. In opposition to the Open Society, Popper first castigates Plato for casting his sympathies with the rulers against the common citizens, believing that Plato wished to himself be the philosopher-king which he cites as the supreme aspiration for society, rather than democratic government. In both Hegel and Marx, he attacks their philosophical systems of teleological historicism: their arguments that history and the fate of humanity unfolds according to universal laws.

Whether in Hegel’s philosophy which saw the World Spirit of history embodied in a singular statesman like Napoleon (which had obvious implications for the rise of Hitler, and which Popper traced to modern fascism), or in Marx’s philosophy which held that history unfolded through clashes of economic classes (previously unseen except by Marx), Popper found that their all-encompassing explanations intentionally took out the complexity of modern societies with outcomes made by the individual decisions and wills of myriad actors. He believed that history’s ends were indeterminate, and that the study of history could not be developed into a predictive science. Popper’s ideas were powerful arguments for roles of freedom of choice in human affairs, ideas very much at the center of the fight against Nazi Germany and Imperial Japan in World War II. After the war, Popper immigrated to the United Kingdom and beginning in 1949 settled at the University of London to teach philosophy. Like Hayek, he lived to see the end of the Cold War before he passed away at age 92 in 1994.

It should be noted that the works of Schumpeter, Hayek, and Popper all were debated and received criticisms for their arguments. But in the spirit of the time in which they were written and published, one can be certain that they all welcomed their ability to debate, exchange ideas, and criticize, as these were the very human rights which were at stake in the fight against Nazi Germany and Imperial Japan in World War II. For students of the history of philosophical, political, and economic thought, their works remain invaluable contributions to the freedom to creatively think about how humanity can establish a better world, even in the midst of the worst war in history.