In Locke scholarship, there are at least two enduring sets of problems: The first has to do with the relationship between Locke's early works—which are frankly authoritarian—and his later works—which are definitively not; the second problem concerns the series of apparent contradictions between Locke's Essay on Human Understanding and his Two Treatises. The strong argument in the Essay against innate ideas and objective morality stands in tension with the natural law argument that is critical to Locke's Second Treatise. In his new and compelling book, Douglas John Casson attempts to resolve both of these questions (and many others) by rereading Locke through the lens of his epistemological concerns. Casson argues that many significant tensions can be explained as an attempt on Locke's part to develop a new standard for public reason and judgment. In fact, Casson suggests that Locke might be best understood as engaged in political pedagogy—using the course of his writing career to show his public how to become citizens capable of freedom and self-government. In the course of making this argument, Casson rereads almost all of Locke's entire corpus through the lens of this epistemological and political project.

Liberating Judgment begins by situating Locke in the intellectual context of waning scholasticism. At the end of the medieval period, the appeal to authority loses its credibility and the scholastic categories of opinio and scientia begin to break down and become fatally inadequate. In the wake of this collapse of scholasticism, two competing epistemological approaches emerge. The first is a dogmatic fanaticism that asserts the truth of subjective conviction and that admits no critique (Casson locates this fanaticism in Cartesian rationalism, as well as religious enthusiasm), and the second is a thoroughgoing skepticism that denies the possibility of certain knowledge. The author shows that the authoritarianism of the Two Tracts is best explained as a political implication of Locke's early skepticism. Locke's breakthrough comes, according to Casson, during his time at Oxford and his engagement with Boyle and the members of the Royal Society. During this period, he becomes convinced that nature does present an objective external moral law, but at the same time he develops a modest epistemological position that takes the form of the “language of probability” (p. 97). Certainty is not possible; the best we can hope for are probable judgments.

This probabilistic approach to knowledge reflects Locke's concern with political practice over metaphysical certainty. Casson emphasizes that Locke is not interested in staking out ontological certainties, but instead offers a language that “could sustain a mode of discourse through which religious, political, and moral claims could be publicly evaluated” (p. 97). Despite retreading some familiar ground, these early historical chapters are among the strongest and most convincing parts of Liberating Judgment. The recovery of the category of judgment and its connection to Locke's political ideal is extremely promising. In short, Casson argues that “[t]he renewed emphasis on probable judgment that he witnessed led him to imagine the possibility of a stable regime consisting of individuals who discipline their judgments according to a shared notion of reasonableness” (p. 101).

In the remainder of the book, Casson uses this normative ideal and the concept of probabilistic judgment to offer a reinterpretation of Locke's most significant works: the Essay and each of the Two Treatises. These analyses culminate in a reading of Locke's justification of revolution through the lens of judgment, which leads Casson to the conclusion that Locke's real goal in the Two Treatises is to incite his audience to take up the task of deliberation and judgment. In the process, Casson uses the lens of probable judgment to take on many of the ongoing controversies in Locke scholarship, as well as to develop new readings of the main texts under discussion. The chief argument here is that Locke's work is best understood as a project seeking to create a new public standard of judgment based on probability and, simultaneously, to urge the creation of self-restrained, epistemologically modest individuals who will be able to use this judgment in “institutions of self-government” (p. 126).

In a book as broad in scope as this one, it is inevitable that some arguments and readings will be more compelling than others. Casson's work is strongest when he brings together historical and textual analysis in the service of his central claim about probabilistic judgment. In addition to the earlier chapters already described, the author gives a fabulous reading of the tension between Locke's claim in the Second Treatise that the law of nature is “so plain was it writ in the Hearts of all Mankind” (2T 11) and his explicit statements of the reverse in the First Treatise and the Essay. By contextualizing Locke's use of the “written on the hearts” language in seventeenth-century discourse and by bringing his own argument about labor and judgment to bear, Casson is able to offer a persuasive new reading of the importance of intellectual labor to the determination of the natural law (p. 228). By contrast, other claims are less convincing or more problematic—for example, the discussion of happiness and the good, or “what is best” in the context of the Essay (pp. 165–66), and the overreach of the fascinating analogy he draws between the intellectual engagement with the world to create the self and the physical engagement with the world to create property (pp. 180–83).

In many cases, the difficulties with Casson's arguments lie in his conclusions. He has a tendency to undermine his analysis by overstating his conclusions, usually by attributing more intentionality to Locke than can really be justified. I take this to be the central flaw in what is a very provocative and compelling book. The language of probability is extremely fruitful in Casson's hands, but he constantly seeks to transform this explanatory lens into a claim about author intentionality. He implies that Locke was self-consciously engaged in a lifelong probabilistic project of political pedagogy and organized his life's work around it (and yet somehow failed to mention this explicitly). This suggestion is not defended textually or contextually but merely taken to be Locke's true focus.

This represents an overreach on Casson's part, and its persistence throughout the book tends to undermine its project. For example, in the section on the Second Treatise—one of the interpretive highlights of the book—Casson argues that the problem of judgment helps to explain the peace of the state of nature, the destruction of that peace by the introduction of money, and the justification of the right to revolution in terms of the possibility of reasonable public judgment. It is a wonderfully compelling reading. However, in his introduction to this section, Casson claims: “The account that Locke presents in the Second Treatise is a defense of a particular type of judgment as the natural right of free and equal individuals and an explanation of how the prudent exercise of that judgment can stave off political conflict and sustain a regime of relative stability and peace. He seeks to convince his readers that they will be able to navigate the complexities of self-government by making reasoned judgments concerning their own welfare and the welfare of the public as a whole” (p. 223). This is an exaggerated conclusion of what will be a compelling analysis. I do not dispute that these are possible effects or implications that can be drawn from Locke's argument, but I take issue with the confident assertion that these tacit effects and implications are, in fact, Locke's ultimate purpose, informing each and every piece of writing in his corpus.

While there are dimensions of Liberating Judgment that non-Straussians will find frustrating and distracting, the book is wonderfully provocative and sheds new light on many of the large and small questions that bedevil Locke scholars. Casson's is an important contribution to the literature on Locke.