First published in 1990. The aim of this thesis is to show that the way to understand the central claims of Kant’s ethics is to accept the idea that morality is a distinctive form of rationality; that the moral "ought" belongs to a system of imperatives based in practical reason; and that moral judgment, therefore, is a species of rational assessment of agents’ actions. It argues, in effect, that you cannot understand Kant’s views about morality if you read him with Humean assumptions about rationality. This title will be of interest to students of philosophy.

This collection contains Warren Quinn's most important contributions to moral philosophy and has been edited for publication by Philippa Foot.

Moral systems, like normative systems more broadly, involve complex mental representations. Rational Rules proposes that moral learning can be understood in terms of general-purpose rational learning procedures. Nichols argues that statistical learning can help answer a wide range of questions about moral thought: Why do people think that rules apply to actions rather than consequences? Why do people expect new rules to be focused on actions rather than consequences? How do people come to believe a principle of liberty, according to which whatever is not expressly prohibited is permitted? How do people decide that some normative claims hold universally while others hold only relative to some group? The resulting account has both empiricist and rationalist features: since the learning procedures are domain-general, the result is an empiricist theory of a key part of moral development, and since the learning procedures are forms of rational inference, the account entails that crucial parts of our moral system enjoy rational credentials. Moral rules can also be rational in the sense that they can be effective for achieving our ends, given our ecological settings. Rational Rules argues that at least some central components of our moral systems are indeed ecologically rational: they are good at helping us attain common goals. Nichols argues that the account might be extended to capture moral motivation as a special case of a much more general phenomenon of normative motivation. On this view, a basic form of rule representation brings motivation along automatically, and so part of the explanation for why we follow moral rules is that we are built to follow rules quite generally.

Kant claims that the fundamental principle of morality is given by pure reason itself. Many have interpreted Kant to derive this principle from a conception of pure practical reason (as opposed to merely prudential reasoning about the most effective means to empirically given ends). But Kant maintained that there is only one faculty of reason, although with both theoretical and practical applications. This Element shows how Kant attempted to derive the fundamental principle and goal of morality from the general principles of reason as such, defined by the principles of non-contradiction and sufficient reason and the ideal of systematicity.

This is a book about morality, rationality, and the interconnections between the two. In it, Portmore defends a version of consequentialism that both comports with our commonsense moral intuitions and shares with consequentialist theories the same compelling teleological conception of practical reasons.

Moral Rationalism and Sharī'a is the first attempt at outlining the scope for a theological reading of Sharī'a, based on a critical examination of why 'Adliyya theological ethics have not significantly impacted Shī'ī readings of Sharī'a. Within Shī'ī works of Sharī 'a legal theory (usūl al-fiqh) there is a theoretical space for reason as an independent source of normativity alongside the Qur’ān and the Prophetic tradition. The position holds that humans are capable of understanding moral values independently of revelation. Describing themselves as 'Adliyya (literally the people of Justice), this allows the Shī 'a, who describe themselves as 'Adiliyya (literally, the People of Justice), to attribute a substantive rational conception of justice to God, both in terms of His actions and His regulative instructions. Despite the Shī'ī adoption of this moral rationalism, independent judgments of rational morality play little or no role in the actual inference of Sharī 'a norms within mainstream contemporary Shī'ī thought. Through a close examination of the notion of independent rationality as a source in modern Shī'ī usūl al-fiqh, the obstacles preventing this moral rationalism from impacting the understanding of Sharī 'a are shown to be purely epistemic. In line with the ‘emic’ (insider) approach adopted, these epistemic obstacles are revisited identifying the scope for allowing a reading of Sharī'a that is consistent with the fundamental moral rationalism of Shī'ī thought. It is argued that judgments of rational morality, even when not definitively certain, cannot be ignored in the face of the apparent meaning of texts that are themselves also not certain. An 'Adliyya reading of Sharī'a demands that the strength of independent rational evidence be reconciled against the strength of any other apparently conflicting evidence, such that independent judgments of rational morality act as a condition for the validity of precepts attributed to a just and moral God.

James P. Sterba offers something that philosophers have long sought: an argument showing that morality is rationally required. Furthermore he argues that morality requires substantial equality. Even libertarian perspectives, which would seem to require minimal enforcement of morality, are shown to lead to a requirement of equality.