In her book, Mary M. Keys makes significant contributions to our understanding of Aquinas, Aristotle, and theories of the common good. Keys makes two fundamental, persuasive arguments: 1) Aquinas's account of the will's natural inclination to virtue (and consequent sociability) and his development of a theory of natural law are deliberate philosophical attempts to correct weaknesses in Aristotle's account of the common good; and 2) in correcting and improving upon Aristotle, Aquinas “is consciously laying new, deeper, and broader foundations for ethics and political science” (p. 111), foundations which are—or should be—of considerable value to contemporary secular (as well as Christian) political thought. Specifically, she argues that Aquinas's new foundations address a persistent difficulty with traditional common good theory: “how to elaborate a ‘unitary but complex’ account of the human good that does justice to the many worthwhile ways of life and the multiple genuine goods that people seek by nature and by choice” (p. 14).

Nine chapters divided into four parts tightly and intricately organize Keys's dazzlingly broad discussion and slightly sprawling prose. Part I makes the case for considering Aquinas as a significant and distinctive contributor to even (indeed, especially) secular contemporary political theory, and situates Aquinas's concerns amidst the work of John Rawls, Michael Sandel, and William Galston. (In subsequent chapters, Alasdair MacIntyre, Henry Jaffa, and Robert George become equally substantial contemporary participants in Keys's exploration.) Part II examines Aquinas's treatment of Aristotle's three political-philosophical foundations: the social nature of human beings (Politics I), the centrality of regimes in forming virtuous citizens and human beings (Politics III), and the problematic (for Aquinas and Keys) account of the universal, best regime (Politics VII–VIII). Aquinas's extension—in the natural goodness of the will and natural law theory—of Aristotle's first two foundations represents, Keys persuasively argues, a fuller and more coherent account of human action, which resolves the Aristotelian tension between the civic and cardinal virtues. In Part III, Aquinas's treatment of magnanimity and legal justice (in his Commentary on Aristotle's “Nicomachean Ethics”) reveals the ways in which the theological virtues and natural law improve upon Aristotle's treatment of the tension between personal and common goods. Part IV transposes these considerations back into the contemporary context. Here, Aquinas's articulation of the corrective and directive moments of the law form “a moderate yet ennobling legal pedagogy of ethical virtue,” which, Keys argues, fosters a “renewed appreciation of religion's role in fostering responsibility, sociality, and solidarity for the common good in social and civic affairs” (p. 226). Throughout, Keys takes care to indicate the large extent to which Aquinas's analysis of Aristotle and his contributions to contemporary political theory are philosophical rather than theological—teleological, to be sure, but also derived from natural reason's account of our interdependence and therefore applicable beyond an exclusively Christian political theory.

Part of Keys's success in presenting her argument is the care she takes in reading familiar questions from the Summa Theologiae (on law, for example, from the “Prima Secundae”) alongside less familiar questions from the “Secunda Secundae.” But her real success comes in viewing the Summa in the light of Aquinas's unfinished commentary on Aristotle's Politics and the full commentary on the Nicomachean Ethics. To see these commentaries as “living works of dialectical inquiry” designed not only to clarify Aristotle's meaning but also to “correct or supplement Aristotle's account” (p. 115) represents an important and demanding methodological strategy that illuminates Aquinas and Aristotle alike. That said, Keys occasionally overplays her hand, as when she needlessly contends that Aquinas deliberately abandoned his commentary on the Politics after Book 3 in response to the insufficiency of Aristotle's third political-philosophical foundation (e.g., p. 99). Such instances do not detract, however, from her penetrating reading of “the commented Politics” as well as the “uncommented Politics” in other Thomistic texts.

Keys's approach bears much fruit in her consideration of Aquinas's reorientation of Aristotelian magnanimity toward the common good; for Keys, Aquinas's integration of humility, gratitude, and self-transcendence with magnanimity moderates “the classical emphasis on self-sufficiency and superiority” (p. 203). Less successful is her account of how Thomistic legal justice provides a resolution to the Aristotelian tension between general moral obligation and regime particularity. She concludes with some thoughtful reflections about state–church cooperation understood in terms of a communal fidelity that accommodates both regime-specific and cosmopolitan-universal virtue (pp. 231–33). In the end, however, she seems to try too hard to make Aquinas compatible with liberalism, even as she demonstrates the important insights Aquinas has to offer contemporary liberal political theory (here, a further elaboration of Aquinas's legal pedagogies might add nuance to her case).

Although her knowledge of the texts and commentaries on both Aquinas and Aristotle is deep and impressive, Keys sometimes writes unevenly for both a specialist and generalist audience. Scholars of Aristotle or Aquinas may find the material on contemporary political theory distracting; contemporary theorists may find her detailed treatment of Aristotle and Aquinas too refined. In some respects, it may have been better for Keys to have written two books, one on Aquinas and Aristotle and another on Aquinas and contemporary political theory. Further, lurking behind her treatment is a third book—fundamental but still unwritten—on the extent and character of Aquinas's debt to Augustine in thinking about natural law and the common good. Finally, she could have written with greater economy, and Cambridge has done author and reader alike a disservice in not taking greater stylistic, typographical, and editorial care.

If the inner workings of some of Keys's presentation require some refinement, however, her overall conclusion still holds: “By incorporating natural law, its broader common good, and the will explicitly into his dialectic, indeed into the very definition of justice, Aquinas is able simultaneously to situate justice more deeply in the interiority of a person and to extend its scope more broadly toward a universal good” (p. 198). Both methodologically and substantively, Keys has charted new paths for thinking about Aristotle, Aquinas, and the common good in contemporary political thought.