"In everyday usage, 'ideology' tends to be a pejorative term, synonymous with the dogmatic or fanatical. This is not the sense in which the term is used in this book. Nor does this book adopt the instrumental approach to ideology, common among social scientists and Marxists, which sees ideology as socially 'determined', rather than as a body of relatively coherent and comprehensive beliefs, of interest in their own right. It is this last feature of ideologies which this book focuses on - namely ideologies' key assumptions and themes, their instrinsic content. This is not to deny that there are interesting questions to be asked about the social origins and role of ideologies. However, these questions would require a separate book to do them justice. Moreover, we live in an age of 'hyper-change'. Suddenly, in the last decade or so, the ideologies which were in the ascendant in the early twentieth century seem to have entered terminal decline, whilst other ideologies have been rejuvenated, and newer ones have grown in force. In general, these changes have undermined the left more than the right, though the rise of new ideologies throughout the twentieth century has helped show the weaknesses classifying ideologies by the traditional left-right spectrum."