This chapter articulates the basic tenets of my Thomistic framework for the ethics of lying and truthfulness in the form of eight theses. Then, to illustrate the practical implications of this framework, I sketch fifteen vignettes of difficult cases in lying, each followed by a brief analysis that draws on relevant features of this framework.

In the first part of this chapter, I defend the view that equivocation is a form of lying, drawing upon Aquinas’s insights to address theoretical questions that are beyond his purview. Later in the chapter, I turn to the “Gestapo Question” to consider how Aquinas’s approach can reframe the classic moral dilemma of lying to save the life of a refugee.

This chapter distills the key insights of Aquinas’s position on lying and demonstrates the value of sustained reflection on this medieval thinker’s complex understanding of the virtue of veracitas.

This chapter charts the importance of the Eighth Commandment (especially as interpreted by Augustine of Hippo) in the medieval scholastic debates about lying. It describes in detail the context in which Aquinas’s interpretive and philosophical ideas would take shape as began to develop his own approach.

This chapter describes Aquinas’s development of the virtue of truthfulness, as he draws upon classical sources (primarily Aristotle and Cicero) to supplement and nuance the traditional Augustinian approach. His understanding of venial sin allows him to further distinguish the kinds of lies that are opposed to the virtue of truthfulness.

This chapter analyzes Aquinas’s mature thought on the sins of speech that are directly opposed to justice. It describes how he begins to part ways with his peers and forebears on the relationship between lying and the Eighth Commandment.

This chapter sets out the aims and scope of the book, and it offers a summary of the primary argument: namely, that Thomas Aquinas’s analysis of lying and truthfulness provides resources for charting a clear path between the rigorist and consequentialist positions on offer in contemporary ethics.

In this chapter, I evaluate five constructive proposals, each motivated in some way by the Christian tradition, that aim to solve some difficult problems about lying. This evaluation highlights the uniqueness of the discourse among Christian ethicists on the morality of lying, while underscoring some of the major problems of this discourse.

In this chapter, I address a widespread problem that is frequently encountered but insufficiently diagnosed, namely, that disregard for truth is accepted and even expected in many contexts, yet it creates conditions for gross injustice and dehumanization. I offer an account of widespread cultural indifference to truth as structural sin, a condition I call truth indifference.