Rene Descartes posed questions about the nature of knowledge and the nature of being that philosophers still debate today. In Meditations, Descartes expands on his most famous pronouncement, "I think, therefore I am," which first appeared in an earlier text.

The Selfish Gene is that rarest of things: an outstanding work of scholarship that has seeped into popular culture. Richard Dawkins's contentious notion that organisms are survival mechanisms for 'selfish genes' has helped shape the debate in evolutionary biology for almost 40 years.

Postmodernist thinkers consider history to be not very far removed from a work of fiction, something dependent on historians' own interpretations of the past. Evans, however, argues that we can trust history and it is possible to be objective about what happened and what caused it to happen.

A game-changer when it was first published in 1961, Who Governs? remains one of the most influential political science books ever written. Dahl argues that American liberal democracy is a pluralist system in which policy is not, as is so often thought, shaped by a small group of powerful individuals.

In Bowling Alone, Robert Putnam argues that Americans have become disconnected from one another and from the institutions of their common life, and investigates the consequences of this change.

Because the potential returns appear to be greater in poorer countries than in the developed world, modern economic theory implies that rich countries should continually invest in poor countries until returns balance out.

After Hegemony has had a huge impact on policy debates over the last three decades. Hegemony means the social, cultural, ideological, or economic influence of one dominant group, and Keohane asks if international cooperation can survive in the absence of a single superpower.

Advertisements for soap. The image of a film star. We accept these common objects as a normal part of our life. But each also carries hidden messages that none of us even suspect - as Barthes demonstrated in his unique analysis of the signs that generate meanings and assumptions we all take for granted.