Rawls first introduces the idea that persons are self-originating sources of valid claims in his 1980 Dewey Lectures as a central element of what he there calls “Kantian Constructivism.” Although this got lost in Rawls’s political turn in Political Liberalism, I argue that the claim that persons are self-originating sources of claims – or, in my terms, that they share a basic second-personal authority to make claims and hold one another accountable – can do real work in grounding justice as fairness (and also “rightness as fairness”) that the Kantian Interpretation in A Theory of Justice is impotent to do. Taken on their own, the materials of the Kantian Interpretation are impotent to support anything in the distinctive conceptual territory of the right, much less, the priority of right. Only the idea that we are fundamentally accountable to one another puts us into the conceptual space of the deontic.

In this chapter, we consider a group of philosophers who formed their views in opposition to voluntarist natural law. Although there are important differences between Spinoza, Cudworth, Shaftesbury, and Leibniz, all four were united by their opposition to voluntarism. For voluntarists, even natural law is a kind of positive law since it is created by God’s discretionary imposition. Against this, Cudworth complained that voluntarism makes morality “positive, arbitrary and factitious only” and unable to explain morality’s “eternal and immutable” character. Leibniz was also a critic of positivist law, and he subversively reinterprets law in terms of love. Justice, he says, is the “charity of the wise.” For his part, Spinoza opposes not just positivist law but law itself. Indeed, although his great metaphysical work is titled Ethics, it constitutes nothing less than a metaphysical reduction of ethical or normative categories. At the same time, he develops a deeply attractive account of human freedom that inspired thinkers to come (including Nietzsche). Shaftesbury draws mostly from Cudworth, but in a way that gives rise to the moral sense tradition of Hutcheson, Hume, and Smith.

No philosopher is more strongly associated with deontological ethics or is a more canonical modern moral philosopher than Immanuel Kant. In this chapter, we focus on Kant, though we begin, after a brief introduction of Kant and his historico-philosophical significance, with Rousseau. Rousseau is best known as a political philosopher, but there are elements of his thought that have great importance for moral philosophy and its history and, especially, for Kant. Kant credits Rousseau as the source of his signature claim of the equal dignity of rational persons. And Rousseau’s conception of political society as an “association” that “defend[s] and protect[s] the person and goods of each associate with the full common force,” but where each “nevertheless obey[s] only himself,” has obvious resonances with Kant’s “kingdom of ends” in which all are governed by self-legislated law. At the same time, Rousseau offers important points of contrast to Kant. Whereas Rousseau’s emphasis is essentially social and political, Kant will attempt to argue for morality as a common law binding all agents that is grounded in practical reason alone. Rousseau, by contrast, points toward an alternative grounding in sociability that is reminiscent more of Grotius, Pufendorf, Smith, and Reid.

Grotius, Hobbes, and Pufendorf are canonical representatives of the early modern natural law tradition. In this chapter, we consider the tradition’s other two main figures: John Locke and Richard Cumberland. Locke is justly famous, of course, though more for his political philosophy and the more familiar topics in epistemology and metaphysics treated in the Essay Concerning Human Understanding than for his ethics. In his moral philosophy, however, he makes interesting connections between moral accountability and autonomy that provide an interesting point of contrast with Pufendorf. Cumberland is much less well known. However, Cumberland’s contemporaries saw him, along with Grotius and Pufendorf, as one of a “triumvirate of seventeenth-century founders of the ‘modern’ school of natural law” (Haakonssen). Moreover, Cumberland has special relevance to moral philosophy of the present day, since he was among the first to attempt to “locate” moral truths and facts in relation to, and perhaps reduce them to, those that are confirmable by the empirical sciences, a naturalist program that remains vital today. And he was also an important source of philosophical utilitarianism.

Hutcheson and Butler were contemporaries whose best-known works appeared within a year of one another. Although they had similar intellectual temperaments and styles, their philosophical approaches differed in important ways that reverberated through thinkers that followed. Both were sharply analytical, and both shared a keen insight into moral psychology. Moreover, both laid great stress on the psychology of moral judgment. Hutcheson called this, following Shaftesbury, “moral sense,” and Butler referred to it alternately as the “principle of reflection” or “conscience.” For both, moral judgment involves the human capacity to (more or less successfully) reflect upon and respond affectively to motives, characters, and actions in dispassionate impartial way. However, the role of moral reflection for these two philosophers is profoundly different. For Hutcheson, it is an observer’s moral sense that enables a person to make moral evaluations of motivation and actions, but these evaluations are not self-reflexive – the agent is not evaluating their own, or even others’, moral sense. For Butler, on the other hand, conscience is a moral faculty by which agents crucially make judgments of themselves, judgments they employ to shape their own actions. Conscience is action-guiding for Butler in a way that moral sense is not for Hutcheson.

In “Modern Moral Philosophy” Anscombe famously argues against the main thrust of European ethical philosophy since the mid-seventeenth century. Her main complaint is that the conceptual structure of modern moral philosophy – focusing on obligation, duty, right, and wrong, rather than the classical Greek focus of virtue and the good life – cannot be sustained without divine legislation, which many moderns have tried to avoid. Modern Moral Philosophy: From Grotius to Kant will carefully analyze both canonical and lesser known texts to demonstrate that philosophers of the period have resources to answer Anscombe’s Challenge. Many of the philosophers studied were central in this: early modern natural lawyers Grotius, Pufendorf, and Hobbes; critics of natural law, like Leibniz and Shaftesbury; moral sentimentalists Hutcheson, Hume, and Smith; rationalists like Clarke, Price, and Reid; and, of course, Kant. One of the most interesting sources of response is a connection many philosophers made between morality and accountability and insights they had about the psychological prerequisites and presuppositions of accountability.

Hobbes and Pufendorf write in Grotius’s wake and take early modern natural law in very different directions. Hobbes attempts to ground his moral and political philosophy in metaphysical materialism and to construct morality and the state with lean materials. A standard view is that he does this on a basis of psychological and rational egoism. This is too simple a view, as reciprocity plays a largely unappreciated role in his moral philosophy. For his part, Pufendorf may seem to be an orthodox theological voluntarist, grounding morality in divine command. On analysis, however, his views prove to be much more interesting. Pufendorf has deep insights about the conceptual conditions of accountability to God – namely, that those subject to divine command be able to hold themselves accountable in their own practical reasoning. And sociability plays an important role in his thought also, though somewhat differently from Grotius.

Hugo Grotius is best known as one of the originators of international law. Philosophers of the period also saw him as making a fundamental break with ancient philosophy and Thomistic classical natural law deriving from Aristotle. Grotius carried forward an important distinction made by Francisco Suarez between “law” and “counsel.” Good moral reasons may counsel action without yet requiring it. Law, by contrast, obligates, and obligation is conceptually related to accountability. It concerns what we would be blameworthy for failing to do without excuse. Grotius develops a theory of natural rights and law and sets the philosophical agenda by asking what could ground such a law (Anscombe’s Challenge). His response is human “sociability,” by which he means not simply any desire to affiliate, but the drive to live with others on terms of mutual accountability.

Hutcheson, Hume, and Smith wrote in opposition to a group of early eighteenth-century philosophers known as the “British rationalists,” which included Samuel Clarke, John Balguy, and William Wollaston. Richard Price was a later entrant in this debate on the rationalist side as, in some ways, was Thomas Reid’s Essays on the Active Powers of the Human Mind, though Reid, like Butler, was hesitant to characterize himself as a rationalist. In this chapter, we shall focus on the central elements of eighteenth-century British rationalism, beginning with Clarke and Balguy, but concentrating mostly on the more philosophically developed and interesting versions in Price and Reid.

The philosophical claims dividing rationalists and sentimentalists were primarily epistemological and metaphysical. Concerning epistemology: How and through what faculties do we judge, and perhaps know the truth of, moral and ethical propositions? And metaphysically: In what do moral and ethical properties consist (if they exist)? Epistemological differences were often grounded in metaphysical disagreements. It has not often been noticed, however, that these also had a fundamental conceptual aspect: The British moralists were concerned with deontic morality and presuppositions of accountability in a way the sentimentalists generally were not.

David Hume and Adam Smith were contemporaries, interlocutors, compatriots, and friends, who, along with Hutcheson, helped shape the remarkable period of intellectual activity in eighteenth-century Scotland known as the Scottish Enlightenment. They inherited Hutcheson’s sentimentalist approach: a form of moral empiricism that is opposed to ethical rationalism and that continues to find resonance today. Hume’s version has had the greatest influence, including in contemporary discussion.

For his part, Adam Smith is, of course, best known for his writings on economics. But Smith’s Theory of Moral Sentiments is arguably one of the greatest works on moral psychology ever written. Smith shows the ubiquity of imaginative perspective-taking in our mental moral lives, both in attributing mental states to others (and in everyday normative judgments of the fittingness, or “propriety” as Smith calls it, of attitudes to the objects they have in view). Moreover, Smith connects fellow-feeling with mutual respect and accountability. Our capacity to take on others’ perspectives and regulate our conduct toward them from an informed and impartial second-personal point of view figures centrally both in Smith’s account of justice.