Professor of Sociology and Director of the London School of Economics Ralf Dahrendorf gives his fourth Reith lecture from his series entitled 'The New Liberty'. In this lecture entitled 'On Difference', Professor Ralf Dahrendorf discusses the concept of diversity and averages. Evaluating the socialist philosophies of different countries, he dissects the averages that are found in society and contemplates what will happen when developing countries try to reassess their status as developed countries.