Philosopher Judith Butler's 1990 work, Gender Trouble, shook the foundations of feminist theory and changed the conversation about gender. While many thinkers already accepted that "gender" was a category constructed by society rather than defined by one's genitalia, Butler went further and argued that gender is performative - it exists only in the acts that express it. Society determines that wearing makeup is "feminine" - but some men wear makeup. Are they "women"?
A self-educated man, Eric Hoffer was most likely born in 1898. He wrote in his spare time after doing shifts on the San Francisco docks, where he continued to work, even after becoming a successful author. Hoffer began writing The True Believer in the 1940s, as Nazism and fascism spread across Europe. Most analysts who were trying to work out how these movements became so powerful focused on their leaders and the ideas they trumpeted.
"Hoffer not analyzed"
How do those in power exercise that power over a state's citizens? French thinker Michel Foucault's 1975 work Discipline and Punish looks to answer this question by investigating the prison system. Foucault does not believe that the modern-day system developed out of reformers' humanitarian concerns. He argues that prison both created and then became part of a bigger system of surveillance that extends throughout society.
In her 1958 work, political theorist Hannah Arendt asks two fundamental questions: "Under what conditions do politics emerge?" and "Under what conditions can politics be eliminated?" In searching for answers she turns some long-established thinking on its head. Ancient political philosophers such as Plato and Aristotle believed that a life spent thinking was more important than an active life of labor, work, and action. But Arendt argues that political action is every bit as important as political thinking.
First published in 1948, Antonio Gramsci's Prison Notebooks is an important Marxist work that says we must understand societies both in terms of their economic relationships and their cultural beliefs. Gramsci wanted to explore why Russia had undergone a socialist revolution in 1917 while other European countries had not. So he developed the concept of hegemony, which is the idea that those who hold power in a society can maintain and use that power because of their own grip on cultural values and economic relationships.
US psychologist Abraham Maslow's 1943 essay "A Theory of Human Motivation" established his idea of humanistic psychology as a "third force" in the field. He outlined a new approach to understanding the mind, saying humans are motivated by their need to satisfy a series of hierarchical needs, starting with the most essential first. He thought it important for the advancement of psychology to identify, group, and rank them in terms of priority.
First published in 1651, Leviathan drove important discussions about where kings get their authority to rule and what those kings must, in turn, do for their people. This is known as the "social contract". Thomas Hobbes wrote the book while exiled from his native England following the English Civil War that unseated King Charles I. In the face of England's radical - if temporary - rejection of its monarchy, Hobbes wanted to explain why it was important to have a strong central government, which in his time meant having a sovereign at its head.
Why do we want to justify our decisions, even if they appear to be irrational? The answer lies in cognitive dissonance, the mental discomfort we experience when we hold two contradictory beliefs at the same time. In A Theory of Cognitive Dissonance, first published in 1957, American social psychologist Leon Festinger investigates the problem. Festinger puts forward the idea that we have developed mechanisms to try to deal with the stress brought on by cognitive dissonance.
Sigmund Freud was born in 1856, in Vienna, Austria, and died in London in 1939, but his reputation as "the father of psychoanalysis" lives on. The theories he introduced in his masterwork, The Interpretation of Dreams, revolutionized the treatment of mental illness in the late 19th century. Based on his success in using new techniques he had developed with his patients, and on conclusions he drew from analyzing his own dreams, Freud said that dreams offered a window into the workings of the unconscious mind.
More than 200 years after Adam Smith published The Wealth of Nations, governments around the world continue to address many of the issues discussed in the book. The most powerful states in the world are still committed to international trade, but questions are repeatedly asked about the role of governments in the economy and the effectiveness of the free market.
Though written around 1513, more than 500 years ago, Italian diplomat Niccolò Machiavelli's The Prince is still very influential. Listeners turn to it for its direct advice on the question of how to attain - and retain - power. Machiavelli's answer, in brief: use any means necessary to make sure the state survives. Given the changeable nature of politics, the strong ruler that Machiavelli describes may need to lie or cheat, deceive and, if necessary, resort to acts of violence - all the while maintaining an "image" of goodness.
More than two centuries after its initial publication in 1781, Immanuel Kant's Critique of Pure Reason remains perhaps the most influential text in modern philosophy. Kant himself claimed his work as a revolutionary document and insisted that it changed the discipline of philosophy as thoroughly as Copernicus had changed astronomy 300 years earlier, when he said the Earth revolved around the sun and not the other way round.
Published in 1980, Michael E. Porter's Competitive Strategy went against the accepted wisdom of the time that said firms should focus on expanding their market share. Porter claimed they should, in fact, analyze the five forces that mold the environment in which they compete: new entrants, substitute products, buyers, suppliers, and industry rivals. Then they could rationally choose one of three "generic strategies" - lowering cost, differentiating their product, or catering to a niche market.
In Philosophical Investigations, the Austrian philosopher Ludwig Wittgenstein presents a radical approach to problems in the philosophy of language and the philosophy of mind. In fact, he sets out a radically new conception of philosophy itself. Published in 1953, two years after Wittgenstein's death, many still consider it one of the finest works of 20th century philosophy.
Western thinking about the Middle and Far East has been distorted by stereotype and inaccuracy. This argument lies at the center of Palestinian-American literary theorist Edward Said's groundbreaking book, Orientalism. Originally published in 1978, it cemented Said's reputation as the father of postcolonial studies.
On the Genealogy of Morality was written in 1887 when Friedrich Nietzsche was at the height of his powers as a philosopher and master of German prose writing. Here, he criticizes the idea that there is just one conception of moral goodness, dissecting the contemporary practice of morality and looking at it from a historical viewpoint. Rather than following a metaphysical or religious approach, Nietzsche adopts a naturalistic framework, which is grounded in history and natural science, to understand our concepts of good and evil in the Christianized Western world.
According to Aristotle, the ultimate human good is eudaimonia, an ancient Greek word that can be translated as happiness, or flourishing. Eudaimonia comes from a life of virtuous (or good) action. Virtues such as justice, restraint, and practical wisdom cannot simply be taught - they must be developed over time by cultivating virtuous habits. The making of virtuous choices can be developed by using practical wisdom and by recognizing the desirable middle ground between extremes of human behavior.
Published in 1961, the year of Frantz Fanon's death, The Wretched of the Earth is both a powerful analysis of the psychological effects of colonization and a rallying cry for violent uprising and independence. The book rejects colonial assumptions that the people of colonized countries need to be guided by their European colonizers because they are somehow less evolved or civilized. Fanon argues that violence is justified to purge colonialism not just from the countries themselves, but from the very souls of their inhabitants.
"Take THAT Amazon's Suggestion Engine!"
In his 2007 book The Black Swan, Nassim Nicholas Taleb says the Black Swans of his title can appear at any time, in the form of financial crises, wars, and other unexpected events that have profound, irreversible consequences. Taleb draws on philosophy, mathematics, economics, and other disciplines to explain in plain English why we seldom prepare for these events adequately. The way our brains process knowledge lull us into believing the future will resemble the past.
History of the Peloponnesian War was the first major work of political inquiry that did not relate events to divine influences. It introduced instead a critical method of looking to the facts of human actions as the basis of our understanding - a method that continues to be used today, more than two millennia later. Many of the most important political thinkers in the Western tradition cite Thucydides as an influence, and major figures including Thomas Hobbes, David Hume, and Friedrich Nietzsche have praised his writing.