Bentham is widely acclaimed as the proponent of the principle of utility. Focusing on the biopolitics of interests, Part I suggests a study of pleasures and pains in Bentham and Foucault from the perspective of Bentham's theorization of the principle of utility. The relevance of such a perspective will appear increasingly justified as the chapters unfold, culminating in the final chapters on the relationship between economics in a liberal state and interests.

The principle of utility, as based on the concept of interests, is not without its contradictions. The aim of this introduction is to highlight these contradictions in order to circumscribe the framework of the debate on pleasures and pains in the following two chapters.

When Foucault refers to the principle of utility, he does have Bentham in mind, but not solely. Indeed, Bentham did not invent the principle of utility. Moreover, in Bentham's theory itself there are different expressions of the greatest happiness principle. At the end of his life, Bentham realized that the previous wording implied a disregard for the welfare of a community and so, in 1827, he changed the phrase ‘the greatest happiness of the greatest number’ into ‘the greatest happiness principle’.

The principle of utility first appeared in Bentham's Fragment on Government and was later systematically exposed in An Introduction to the Principles of Morals and Legislation. Utility is both a psychological and an ethical concept.