This book is basically about the role of political and economic philosophy (‘ideas’) in the processes of belief-formation and social change. I have tried to bring out and examine in more detail a point which economic philosophers of all persuasions have largely taken for granted in their works, and to address an issue – the relations between ideas, interests and behaviour – about which sweeping and confident claims have only too often been made, but which has rarely been subjected to critical and sustained discussion. The object of this work is to further our understanding of the behaviour of the individual economic agent by bringing to light and examining the function of non-rational dispositions and motivations (‘passions’) in the determination of the agent's beliefs and goals.

Drawing on the economic psychology put forward by David Hume, Adam Smith and a few other ‘enlightened sceptics’, I suggest that agents act on the basis of what they believe is their own selfinterest, but that this opinion of interest is best understood as being determined by the non-rational or sensitive rather than by the rational or cogitative part of the human mind. Man, according to this view, is not a rational animal, but something altogether more tentative, affective, unstable and perhaps interesting too: an animal which has the capability of reason. To exercise and live up to this capability, I hold, is an endless and sometimes tricky struggle.