In antebellum America, as in pre-industrial England, it was commonplace to witness civilians accompanying sheriffs and justices, scouring the countryside in search of scoundrels, scalawags, and other law-breakers. These civilians were the posse comitatus, or uncompensated, temporarily deputized citizens assisting law enforcement officers. At its core, the posse comitatus was a compulsory institution. Prior to the advent of centralized police forces, sheriffs and others compelled citizens to serve “in the name of the state” to execute arrests, level public nuisances, and keep the peace, “upon pain of fine and imprisonment.” Despite its coercive character, though, the posse was widely understood as one among many compulsory duties that protected the “public welfare.” Americans heeded the call to serve in local posses, explained jurist Edward Livingston, because of communal “ties of property, of family, of love of country and of liberty.” Such civic obligations, wrote Alexis de Tocqueville in 1835, illustrated why Americans had such a pressing “interest in … arresting the guilty man.” At once coercive and communitarian, lamented Henry David Thoreau, the posse comitatus exemplified how those that “serve the state … with their bodies,” were “commonly esteemed good citizens.”

The essence of the contract of employment is the performance of service in exchange for wages. As such, labor assumes a commodity form—a capacity that is bought and sold in labor markets. But because labor cannot be separated from its bearer, and is not produced for the market, it has been widely recognized as a special or fictive commodity that has been the subject of a distinct legal regime. Historically, that distinct regime—here referred to as employment law—has served both disciplinary and protective functions. On the one hand, it assists employers to extract from the worker the value of the labor they have purchased, while on the other it protects workers against unacceptable exploitation. While these functions are a constant, the scope and techniques of legal discipline and protection vary over time and place, as does the balance between them, depending on such factors as the development of social relations of production, the balance of power between workers and employers, dominant ideologies, etc. In the fulfillment of these functions, law has encountered a series of recurring dilemmas that stem structurally from labor's special commodity status and socially and politically from conflicts between workers' and employers' interests.

Addressing an audience of medical students in 1810, the Philadelphia physician Benjamin Rush recounted a recent call he had made, in consultation with a Dr. Physick, to the residence of “a lady in this city, equally admired for her amiable virtues and elegant accomplishments.” As they were seated in the parlor, she related her medical complaint: “I am blessed with one of the best of husbands, and a family of promising children, whom I love most affectionately,” she began, “and yet, in the paroxysms of my disease, and with the perfect exercise of my reason, I wish for an ax, that I might split open their heads, and lay them all dead at my feet.” Upon hearing this terrible confession, Rush was convinced that he was faced with a case of “moral derangement.” By this, he meant “that state of mind in which the passions act involuntarily through the instrumentality of the will,” a condition he linked to an underlying physical disorder. Since this form of derangement was most clearly manifest in the commission of crime, Rush explained, it was invariably mistaken for ordinary depravity in courts of law, with tragic results. In fact, he reckoned that if his patient were to succumb to her morbid impulses, her fate would be sealed: all her virtues and accomplishments would prove insufficient to save her “from expiating her disease by an ignominious death.” Rush further observed that there was cause for concern on the civil side of the docket as well, for it appeared that the morally deranged were left free to make wholly unnatural dispositions of their estates, to the great injury of their unoffending families. In light of this state of affairs, he charged his students with broader “objects and duties” than simply caring for their patients. It was, he insisted, a physician's civic obligation to extend the benefits of his science “to the protection of property and life” through the cultivation of a distinctly “medical jurisprudence.”

In “Mind of a Moral Agent,” Susanna Blumenthal elegantly limns the rise and partial fall of the common sense theory of moral responsibility in American law. As Blumenthal convincingly describes it, the problem for early American jurists was nothing less than to solve the paradox of determinism and free will. How can the law declare someone morally culpable unless we are free to choose our own ends?

One overriding concern I have with Susanna Blumenthal's insightful and stimulating article, “The Mind of a Moral Agent: Scottish Common Sense and the Problem of Responsibility in Nineteenth-Century American Law,” is whether there is anything sufficiently distinctive about Scottish Common Sense philosophy that justifies the role Blumenthal ascribes to it. In a representative passage, she writes:

Common Sense philosophy left would-be “moral managers” with a puzzle. If rational and moral faculties were innate and universal, what explained the great conflicts among men concerning matters of belief, manners, and morals … leading some to commit acts that were … patently irrational or downright evil? And to the extent that there was a common sense about the dictates of reason, propriety, and moral sense, why did some individuals act in defiance of them?

The authors of these insightful and stimulating commentaries all express skepticism about the role I assign to the Scottish Common Sense philosophy in my historical analysis, though their reasons for doing so are strikingly at odds with each other. Sarah Seo and John Witt concede the importance of the Common Sense philosophy at a theoretical level, even as they call attention to certain “competitor theories” of human nature, noting that these darker views of the self may have proved more influential in the framing of the American constitution. However, they go on to contend that all of this philosophizing about the human mind was actually of little consequence in the everyday adjudication of civil and criminal liability, as judges found more practical means of resolving “the otherwise intractable questions of moral responsibility” left unanswered by the Scottish philosophy. John Mikhail, by contrast, appears to be far more sanguine about the tractability of these questions, from a philosophical standpoint, going so far as to suggest that they were more or less resolved by British moralists before the Scottish Common Sense school even came into being. What truly set the Common Sense philosophers apart from their predecessors, and ought to determine their place in this history of ideas, Mikhail concludes, was the manner in which they contributed to the scientific process of tracing out the inner structure and innate capacities of “the moral mind”—a topic that is currently of intense interest in the cognitive and brain sciences.