The introduction explains the nature of the study, its motivation, its basic structure, and its organization. It draws special attention to the way the book offers a novel interpretation of Aquinas’s account of individual happiness that is remarkably interesting philosophically. It also emphasizes the roles of individual happiness, common happiness, and Holistic Eudaimonism in Aquinas’s efforts to produce a unified ethical system in which law, virtue, and grace also have an important place.

Because the full reconstruction emerges piecemeal over the course of the study, this chapter starts by summarizing the most fundamental ways in which Aquinas connects the big-picture elements of his ethics through his understanding of happiness, both individual and common. The chapter then offers reasons for thinking that Aquinas’s ethics of happiness is still worth taking seriously today. In particular, it focuses on three illustrative aspects that make Aquinas’s ethical views distinctive and appealing. The first is Aquinas’s account of the nature of happiness and how that account fits into his broader understanding of well-being. The second is Aquinas’s account of the relationship between the right and the good. The third is Aquinas’s account of the most comprehensive role that virtue plays in ethics and human life.

This chapter explains the many ways in which individual happiness and common happiness are related to Aquinas’s account of virtue. It begins by arguing that virtue is strictly necessary in order for an individual to be happy, but still virtue is not a constitutive part of that happiness. Rather, it is strictly necessary because virtue alone enables the individual to engage in and enjoy genuinely good activities. The chapter then argues that, still, according to Aquinas, virtue is more deeply related to common happiness than individual happiness inasmuch as a character trait is a virtue of character fundamentally because it enables a person to play their part in realizing the common happiness of their community, not their own individual happiness. The chapter thereby establishes the third element of Aquinas’s Holistic Eudaimonism. The remainder of the chapter shows how the master virtues of general justice and charity as well as a whole host of other particular virtues concern aiming at and securing common happiness for the community.

This chapter explains the many ways in which individual happiness and common happiness are related to Aquinas’s account of law, both generally and with respect to some particular laws. The chapter begins by arguing that, by its very nature, every genuine law orders the things under it to the common happiness of some community or other. It then argues that, according to Aquinas, moral laws order us to common happiness by outlining universal and absolute rules that must be followed in order to fully realize common happiness. Unlike many have thought, then, Aquinas holds that our moral obligations are fundamentally determined by facts about which norms must be followed in order to realize common happiness, not individual happiness. That is the second element of his Holistic Eudaimonism. On the other hand, when it comes to civil laws, the chapter argues that Aquinas advocates a kind of top-down, restricted rule-consequentialism with common happiness as its goal.

This chapter starts by arguing that, for Aquinas, common happiness is a fundamental and crucial notion, despite the fact that he very seldom discusses it and it has largely been ignored by commentators. It then sets out Aquinas’s understanding of the nature of common happiness with special attention to two models of common happiness, namely, the community of heaven and true friendship. The chapter then argues for the perhaps unprecedented claim that Aquinas is committed to the idea that common happiness is the true ultimate end of each human being. It thereby establishes the first element of Aquinas’s Holistic Eudaimonism.