Schaeffer's Giambattista Vico on Natural Law: Religion, Rhetoric and Sensus Communis introduces the reader into the philosophy of Giambattista Vico, an author who is probably not widely known by the American public. Even if there are plenty of professors in the US academy who have researched Vico's thought (Pompa, Caponigri, Miner, Mazzotta, Lollini, etc.), it is not usual to introduce the Italian philosopher into the current debates. It is for that reason that Schaeffer's book opens a new perspective for readers: that is, he brings Vico's philosophy back in order to examine the scope, the limits, and the inner possibilities of natural law from the Neapolitan critics. In this sense, Schaeffer is aware of the complexities of Vico's works. Consequently, every angle taken implies a selection of his philosophy that is illuminated, while other aspects remain inevitably darkened. Schaeffer has preferred to analyze the political aspect of Vico's thought in relation to the rhetorical aspects.

The book's structure is clear and consistent, reassuming every past step in the next chapter. Leaving the synopsis out (since the author takes care of that task in the introduction), the common thread of this work should be pointed out. The natural law debate must be understood from at least two perspectives: first, the context in which the natural law and the social contract appears in the modern age (Grotius, Puffendorf, Hobbes, etc.); second, the essential requirements for a natural law theory nowadays, which continues in the Thomist tradition.

Nonetheless, Vico's philosophy reexamines the first perspective and allows us to sketch out the second. In the first place, Vico considers that human nature is historically constituted and emerges from the ius gentium. The positive law is formulated from a shared sensus communis in a community. This formulation emerges from an anthropological tendency to express metaphorically those behaviors and natural events which are not rationally comprehended by primitive minds. Contrary to the alleged tendency to associate the individuals into a community by a contract, Vico assumes the communal contract in the very beginnings of humankind. As inheritors of the modern social contract, philosophers like Kant, Rawls, or Sen assume the same problem that Vico tries to solve: human nature shall not be an abstraction that explains historical communities. On the contrary, the abstraction is possible thanks to historical development.

In the second place, Schaffer uses Vico's philosophical results to evince the assumptions and limits in the discussion of current Thomists concerned with natural law. As they insist on relating a theological fundament to a pure rationality in God's creation (that is, the formal composition of every rational human being), they fall into analogous presumptions as the modern theorists. Notwithstanding religion, which is a fundamental basis to every culture, there is no need in Vico's philosophy to maintain a Christian God or an abstract soul to posit a social contract. Religion just shows the potential of development of every social objectification. The absence they have in common is the omission of the cultural and historical ground, on which Vico constantly insists.

However, these two perspectives are simply not enough: political effectiveness depends always on rhetorical power, which is also shaped in a historical and communal tradition, located in the current sensus communis of a society. As a society, we can trust in objective rights, but we shall remember the origin of themselves. We also can discuss the present political situations, but our effectiveness depends on the link to our genealogical heritage that still operates.

To conclude, one should remark on Schaffer's difficult labor to maintain in equilibrium a decent comprehension of Vico's philosophy and its application to current political problematics of our days. Even if some elements of Vico's thought can be discussed by scholars (for instance, the role of providence, close to Berlin's assumptions), the whole work accomplishes a double task: it serves as an excellent introduction to Vico's work nowadays, and it opens a profitable philosophical debate.