This book is the Spanish translation of Ignorance and Liberty published in 2003 by Routledge, London – NY. Running from antiquity to the present day, there is a single premise uniting all those who believe in a open society: that the demand for liberty rests on the recognition of human ignorance – we need to be free because we are ignorant and fallible. Free social cooperation permits us to mobilize our knowledge and develop methods of discovery through which we can explore the unknown and continually correct our errors. To assent to free cooperation is to accept critical discussion and democracy, and in this way we are able to increase our rationality and further political and economic development. Improvement in the conditions of our lives, therefore, does not come from the omniscience attribuited to some enlightened legislator or planner. Ignorance and Liberty examines how the market liberates us from this idea of a privileged source of knowledge, by presenting the market as a place not only where good are exchanged, but also where different philosophical ideas and religious beliefs must cohabit. In this way, new horizons are opened up and the sense of an absolute that prevails in a clodes world is undermined.