This book provides the first unified overview of the burgeoning research area at the interface between Quantum Foundations and Quantum Information. Topics include: operational alternatives to quantum theory, information-theoretic reconstructions of the quantum formalism, mathematical frameworks for operational theories, and device-independent features of the set of quantum correlations. Powered by the injection of fresh ideas from the field of Quantum Information and Computation, the foundations of Quantum Mechanics are in the midst of a renaissance. The last two decades have seen (...) an explosion of new results and research directions, attracting broad interest in the scientific community. The variety and number of different approaches, however, makes it challenging for a newcomer to obtain a big picture of the field and of its high-level goals. Here, fourteen original contributions from leading experts in the field cover some of the most promising research directions that have emerged in the new wave of quantum foundations. The book is directed at researchers in physics, computer science, and mathematics and would be appropriate as the basis of a graduate course in Quantum Foundations. (shrink)

We investigate general probabilistic theories in which every mixed state has a purification, unique up to reversible channels on the purifying system. We show that the purification principle is equivalent to the existence of a reversible realization of every physical process, namely that every physical process can be regarded as arising from a reversible interaction of the system with an environment, which is eventually discarded. From the purification principle we also construct an isomorphism between transformations and bipartite states that possesses (...) all structural properties of the Choi Jamiolkowski isomorphism in quantum mechanics. Such an isomorphism allows one to prove most of the basic features of quantum mechanics, like e.g. existence of pure bipartite states giving perfect correlations in independent experiments, no information without disturbance, no joint discrimination of all pure states, no cloning, teleportation, no programming, no bit commitment, complementarity between correctable channels and deletion channels, characterization of entanglement-breaking channels as measure-and-prepare channels, and others, without resorting to the mathematical framework of Hilbert spaces. (shrink)

Entanglement is one of the most striking features of quantum mechanics, and yet it is not specifically quantum. More specific to quantum mechanics is the connection between entanglement and thermodynamics, which leads to an identification between entropies and measures of pure state entanglement. Here we search for the roots of this connection, investigating the relation between entanglement and thermodynamics in the framework of general probabilistic theories. We first address the question whether an entangled state can be transformed into another by (...) means of local operations and classical communication. Under two operational requirements, we prove a general version of the Lo-Popescu theorem, which lies at the foundations of the theory of pure-state entanglement. We then consider a resource theory of purity where free operations are random reversible transformations, modelling the scenario where an agent has limited control over the dynamics of a closed system. Our key result is a duality between the resource theory of entanglement and the resource theory of purity, valid for every physical theory where all processes arise from pure states and reversible interactions at the fundamental level. As an application of the main result, we establish a one-to-one correspondence between entropies and measures of pure bipartite entanglement and exploit it to define entanglement measures in the general probabilistic framework. In addition, we show a duality between the task of information erasure and the task of entanglement generation, whereby the existence of entropy sinks (systems that can absorb arbitrary amounts of information) becomes equivalent to the existence of entanglement sources (correlated systems from which arbitrary amounts of entanglement can be extracted). (shrink)

We review a recent approach to the foundations of quantum mechanics inspired by quantum information theory. The approach is based on a general framework, which allows one to address a large class of physical theories which share basic information-theoretic features. We first illustrate two very primitive features, expressed by the axioms of causality and purity-preservation, which are satisfied by both classical and quantum theory. We then discuss the axiom of purification, which expresses a strong version of the Conservation of Information (...) and captures the core of a vast number of protocols in quantum information. Purification is a highly non-classical feature and leads directly to the emergence of entanglement at the purely conceptual level, without any reference to the superposition principle. Supplemented by a few additional requirements, satisfied by classical and quantum theory, it provides a complete axiomatic characterization of quantum theory for finite dimensional systems. (shrink)

In quantum theory every state can be diagonalized, i.e. decomposed as a convex combination of perfectly distinguishable pure states. This elementary structure plays an ubiquitous role in quantum mechanics, quantum information theory, and quantum statistical mechanics, where it provides the foundation for the notions of majorization and entropy. A natural question then arises: can we reconstruct these notions from purely operational axioms? We address this question in the framework of general probabilistic theories, presenting a set of axioms that guarantee that (...) every state can be diagonalized. The first axiom is Causality, which ensures that the marginal of a bipartite state is well defined. Then, Purity Preservation states that the set of pure transformations is closed under composition. The third axiom is Purification, which allows to assign a pure state to the composition of a system with its environment. Finally, we introduce the axiom of Pure Sharpness, stating that for every system there exists at least one pure effect occurring with unit probability on some state. For theories satisfying our four axioms, we show a constructive algorithm for diagonalizing every given state. The diagonalization result allows us to formulate a majorization criterion that captures the convertibility of states in the operational resource theory of purity, where random reversible transformations are regarded as free operations. (shrink)

This presentation provides a non-technical overview of the notion of quantum superposition of causal structures, of its applications, and of its proposed physical realizations. The conceptual underpinning for these investigations is a view of quantum theory as a new kind of probability theory. At the axiomatic level, the principles of this new kind of probability theory suggest new causal relations that have no analogue in the classical world. These new causal relations are a potential resource for new technologies, including computation (...) and communication technology. (shrink)

The brains of higher mammals are extraordinary integrative devices. Signals from large numbers of functionally specialized groups of neurons distributed over many brain regions are integrated to generate a coherent, multimodal scene. Signals from the environment are integrated with ongoing, patterned neural activity that provides them with a meaningful context. We review recent advances in neurophysiology and neuroimaging that are beginning to reveal the neural mechanisms of integration. In addition, we discuss concepts and measures derived from information theory that lend (...) a theoretical basis to the notion of complexity as integration of information and suggest new experimental tests of these concepts. (shrink)

Integrated information theory (IIT) starts from the essential properties of experience and translates them into requirements that any physical system must satisfy to be conscious. It argues that the physical substrate of consciousness (PSC) must constitute a maximum of irreducible, internal cause‐effect power of a specific form, and provides a calculus to determine, in principle, both the quality and the quantity of an experience. Applied to the brain, IIT predicts that the spatio‐temporal grain of the neural units constituting the PSC, (...) and the relevant neural states, are those that maximize cause‐effect power. Moreover, the PSC can shrink, move, split and disintegrate depending on various anatomical and physiological parameters. These predictions are testable with brain stimulation and recording experiments. The theory can explain parsimoniously many known facts about the relationship between consciousness and the brain, including its association with certain cortical structures, its breakdown in deep sleep, anesthesia and seizures, and its return in dreams. (shrink)

Integrated information theory (IIT) starts from the essential properties of experience (axioms) and translates them into requirements that any physical system must satisfy to be conscious (postulates; see Integrated Information Theory of Consciousness: An Outline, this volume). The postulates of IIT can be seen as a list of requirements for something to exist ‘for itself’, as an intrinsic entity, and thus have relevance for ontology and metaphysics. Some implications of the theory include the divide between intrinsic and extrinsic entities, the (...) incoherence of ontological reductionism, and the intrinsic nature of meaning. (shrink)

Uncovering the neural basis of consciousness is a major challenge to neuroscience. In this Perspective, Tononi and colleagues describe the integrated information theory of consciousness and how it might be used to answer outstanding questions about the nature of consciousness.

The science of consciousness has made great strides by focusing on the behavioural and neuronal correlates of experience. However, while such correlates are important for progress to occur, they are not enough if we are to understand even basic facts, for example, why the cerebral cortex gives rise to consciousness but the cerebellum does not, though it has even more neurons and appears to be just as complicated. Moreover, correlates are of little help in many instances where we would like (...) to know if consciousness is present: patients with a few remaining islands of functioning cortex, preterm infants, non-mammalian species and machines that are rapidly outperforming people at driving, recognizing faces and objects, and answering difficult questions. To address these issues, we need not only more data but also a theory of consciousness a sh one that says what experience is and what type of physical systems can have it. Integrated information theory does so by starting from experience itself via five phenomenological axioms: intrinsic existence, composition, information, integration and exclusion. From these it derives five postulates about the properties required of physical mechanisms to support consciousness. The theory provides a principled account of both the quantity and the quality of an individual experience, and a calculus to evaluate whether or not a particular physical system is conscious and of what. Moreover, IIT can explain a range of clinical and laboratory findings, makes a number of testable predictions and extrapolates to a number of problematic conditions. The theory holds that consciousness is a fundamental property possessed by physical systems having specific causal properties. It predicts that consciousness is graded, is common among biological organisms and can occur in some very simple systems. Conversely, it predicts that feed-forward networks, even complex ones, are not conscious, nor are aggregates such as groups of individuals or heaps of sand. Also, in sharp contrast to widespread functionalist beliefs, IIT implies that digital computers, even if their behaviour were to be functionally equivalent to ours, and even if they were to run faithful simulations of the human brain, would experience next to nothing. (shrink)

In juxtaposition with the myth and tragedy of Ovid’s Medea, this paper investigates the possibility within the Kantian conception of agency of understanding moral evil as acting against one’s better judgment. It defends the thesis that in Kant self-deception, i. e. the intentional untruthfulness to oneself, provides the fundamental structure for choosing against the moral law. I argue that, as Kant’s thought progresses, self-deception slowly proceeds to become the paradigmatic case of moral evil. This is discussed with regard to two (...) important topics in his later moral philosophy: the doctrine of radical evil and the crucial role of the duty of truthfulness in ethics. The inquiry into Kant’s theory of conscience unfolds both against this theoretical background and in light of its historical roots in the polemic against casuistry and probabilism. This contribution closes with a brief look at the tools Kant implements to counter this tendency to self-deception in moral judgment and particularly at the role casuistry plays within his conception of moral education. (shrink)

The target article misrepresents the foundations of integrated information theory and ignores many essential publications. It, thus, falls to this lead commentary to outline the axioms and postulates of IIT and correct major misconceptions. The commentary also explains why IIT starts from phenomenology and why it predicts that only select physical substrates can support consciousness. Finally, it highlights that IIT's account of experience – a cause–effect structure quantified by integrated information – has nothing to do with “information transfer.”.

ABSTRACT This article analyses the abbé de Saint-Pierre as a mediator of ideas between France and England. The political proposal of the Projet pour rendre la paix perpétuelle en Europe circulated in Great Britain just before the signing of the peace treaties of Utrecht and Aachen, attesting the influence that Saint-Pierre’s proposal exerted on British thought and politics. The abbé was engaged in dialogue with Quaker pacifists and, in particular, with the projects put forward by William Penn and John Bellers, (...) both theorists of a ‘European State’. After examining the relationship between Penn’s Essay and Saint-Pierre’s ideas, the article will demonstrate how elements of Bellers’s Some Reasons found their way into the Projet with numerous convergences of lexicon and content suggesting that the abbé had drawn inspiration from Bellers. Quaker ideas on politics had a greater effect on Saint-Pierre’s conception of peace and international relations than is commonly recognized. In fact, there was a constant intellectual exchange between the abbé and British political, economic and philosophical thought. (shrink)

The extended mind thesis states that the mind is not brain-bound but extends into the physical world. The philosophical debate around the thesis has mostly focused on extension towards epistemic artefacts, treating the phenomenon as a special capacity of the human organism to recruit external physical resources to solve individual tasks. This paper argues that if the mind extends to artefacts in the pursuit of individual tasks, it extends to other humans in the pursuit of collective tasks. Mind extension to (...) other humans corresponds essentially to the ‘we-mode’ of cognition, the unique power of human minds to be jointly directed at goals, intentions, states of affairs, or values. Because the capacity for collective intentionality holds evolutionary and developmental primacy over human-epistemic artefacts relations, the extended mind should not be seen as a special phenomenon, but as a central aspect of the human condition. The original extended mind thesis carried important implications for how the cognitive sciences should proceed. In a version of the thesis that accommodates collective intentionality, these implications would go far deeper than originally assumed. (shrink)

The capabilities approach is the theory according to which, in order to assess people's quality of life and reflect on the basic political entitlements, we should consider what people are capable of doing and being. Focusing mostly on Nussbaum's account, a number of scholars analysed the metaethical structure underlying the approach, showing her Aristotelian and Kantian sources. This article explores another aspect of Nussbaum's theory which has so far been somewhat overlooked: the role of emotions in the justification and motivational (...) support of the approach. After showing the importance Nussbaum places on compassion (and other benevolent emotions) to warrant her moral theory, I argue that – assuming her own cognitive account of compassion – her argument begs the question. I will then contend that Nussbaum's case does not have the inner tools to overcome such a circularity, trying to suggest, in conclusion, a possible way out which is consistent with it. (shrink)

The philosophy of emotions has long been dominated by the view called «cognitivism». According to it, emotions are characterized not by mere physical impulses but by a cognitive evaluation of their object. However, despite their success, cognitive theories have to deal with various objections and are divided on how to answer to them. In this essay I want to defend the form of cognitivism claimed by Martha Nussbaum from the most common criticisms. After a brief summary of her account, I (...) confront some of the objections that have been raised against it. In Section 2 I deal with the classic problem of emotions in infants and animals, which lack linguistic abilities. Later, I confront the potential problem represented by cases in which one’s emotion and reasoned judgment seem to differ: in paragraph 3 I consider irrational phobias and fears, to show how they can be accounted for in terms of judgments and thoughts, and not only of perceptions; in paragraph 4 I deal with the objection that «judgementalist» theories violate the «principle of charity», for they ascribe an excessive irrationality to people. I argue that experimental evidence suggest that it is not implausible to assume that people have contradictory beliefs under conditions of uncertainty, and that perceptual theories of emotion fail to account for some fundamental aspects of these phenomena. Finally, in paragraph 5, I deal with the objection according to which a cognitive-evaluative theory cannot explain the sense of passivity that we commonly experience in emotions. (shrink)

In this paper, in line with the general framework of value-sensitive design, we aim to operationalize the general concept of “Meaningful Human Control” in order to pave the way for its translation into more specific design requirements. In particular, we focus on the operationalization of the first of the two conditions investigated: the so-called ‘tracking’ condition. Our investigation is led in relation to one specific subcase of automated system: dual-mode driving systems. First, we connect and compare meaningful human control with (...) a concept of control very popular in engineering and traffic psychology, and we explain to what extent tracking resembles and differs from it. This will help clarifying the extent to which the idea of meaningful human control is connected to, but also goes beyond, current notions of control in engineering and psychology. Second, we take the systematic analysis of practical reasoning as traditionally presented in the philosophy of human action and we adapt it to offer a general framework where different types of reasons and agents are identified according to their relation to an automated system’s behaviour. This framework is meant to help explaining what reasons and what agents play a role in controlling a given system, thereby enabling policy makers to produce usable guidelines and engineers to design systems that properly respond to selected human reasons. In the final part, we discuss a practical example of how our framework could be employed in designing automated driving systems. (shrink)

Placebos are commonly defined as ineffective treatments. They are treatments that lack a known mechanism linking their properties to the properties of the condition on which treatment aims to intervene. Given this, the fact that placebos can have substantial therapeutic effects looks puzzling. The puzzle, we argue, arises from the relationship placebos present between culturally meaningful entities, our intentional relationship to the environment and bodily effects. How can a mere attitude toward a treatment result in appropriate bodily changes? We argue (...) that an ‘enactive’ conception of cognition accommodates and renders intelligible the phenomenon of placebo effects. Enactivism depicts an organism’s adaptive bodily processes, its intentional directedness, and the meaningful properties of its environment as co-emergent aspects of a single dynamic system. In doing so it provides an account of the interrelations between mind, body and world that demystifies placebo effects. (shrink)

We study how to postpone the application of the reductio ad absurdum rule (RAA) in classical natural deduction. This technique is connected with two normalization strategies for classical logic, due to Prawitz and Seldin, respectively. We introduce a variant of Seldin’s strategy for the postponement of RAA, which induces a negative translation from classical to intuitionistic and minimal logic. Through this translation, Glivenko’s theorem from classical to intuitionistic and minimal logic is proven.

We study how to postpone the application of the reductio ad absurdum rule ) in classical natural deduction. This technique is connected with two normalization strategies for classical logic, due to Prawitz and Seldin, respectively. We introduce a variant of Seldin’s strategy for the postponement of \, which induces a negative translation from classical to intuitionistic and minimal logic. Through this translation, Glivenko’s theorem from classical to intuitionistic and minimal logic is proven.

This paper discusses a recent puzzle concerning the notions of boundary parthood and dependence, and offers a new solution. The puzzle was originally presented by Jeroen Smid and successively elaborated upon by Claudio Calosi. I first reformulate some of the troublesome premises. Particularly, whereas Smid and Calosi discuss the puzzle in terms of an underspecified notion of dependence, I propose to construe it in terms of the notion of grounding. In this manner, the dependence relation inherently carries an asymmetry, and (...) we can effectively utilize its four places. The solution I advance precisely takes advantage of this feature of dependence. My proposal avoids the contradiction while still respecting the intuitions driving the original premises. It is also fully compatible with boundaries being only generically dependent on their wholes. (shrink)

The term ‘recalcitrant emotions’ refers to those cases where we feel an emotion that apparently contradicts our better judgements. For instance, one may be afraid of flying while claiming not to believe that it is dangerous. This phenomenon is commonly conceived as an objection to cognitivism, according to which emotions are based on the subject's beliefs, insofar as it would force us to ascribe to the subject who feels them an excessive degree of irrationality, comparing recalcitrant emotions to contradictory beliefs. (...) For this reason, many philosophers have developed perceptual theories which describe emotions as forms of perception, allowing us to explain recalcitrant emotions without attributing to the subject contradictory beliefs, treating them as perceptual illusions. Facing the most compelling of these attempts, the article shows that perceptual accounts fail to explain in what sense recalcitrant emotions (and people who feel them) are irrational, keeping the comparison with optical illusions, which are not. Having rebutted three popular perceptual proposals, I conclude that the analogy between emotions and perceptions is flawed and that the appeal of these theories lies on a surreptitious shift in the meaning of the term ‘perceive’. (shrink)

People with mild to moderate intellectual or multiple disabilities may have serious difficulties in accessing leisure events, managing communication exchanges with distant partners, and performing functional daily activities. Recently, efforts were made to develop and assess technology-aided programs aimed at supporting people in all three areas. This study assessed a new technology-aided program aimed at helping four participants with intellectual and multiple disabilities in the aforementioned areas. The program, which was implemented following a non-concurrent multiple baseline across participants design, relied (...) on the use of a smartphone or tablet connected via Bluetooth to a two-switch device. This device served to select leisure and communication events and to control the smartphone or tablet’s delivery of step instructions for the activities scheduled. Data showed that during the baseline phase, three participants failed in each of the areas while one participant managed to access a few leisure events. During the intervention phase, all participants managed to independently access leisure events, make telephone calls, and carry out activities. These results suggest that the program might be a useful tool for helping people with intellectual and multiple disabilities improve their condition in basic areas of daily life. (shrink)

In 1788, the Tuscan intellectual Giovanni Maria Lampredi (1731–1793) published in Florence his most famous treatise, Del commercio dei popoli neutrali in tempo di guerra, conceived as a reply to his well-known opponent, Ferdinando Galiani. Since then, many scholars have claimed that Lampredi’s reflection upon neutral trade remains one of the most objective academic contributions on the subject. Furthermore, these interpretations have generally analysed Lampredi’s Del commercio without taking into account the context of the work or the author’s real political (...) intents and intellectual goals. Therefore, the aim of this article is to provide a new interpretation of Lampredi’s ideas on trade and neutrality, demonstrating that, far from being impartial, his theories allow us to appreciate the intellectual dimension of the strategies formulated by European and Mediterranean small powers, such as Tuscany, to buttress their neutral policies and independence. In addition, Del commercio proposed an original conception of neutrality which urged Italian small states to pursue a more autonomous and profitable foreign and commercial policy, taking advantage of their sovereignty and neutral condition. Lampredi’s thought, then, requires us to reconsider the relationship between small powers and neutrality in eighteenth-century Europe. (shrink)

Contemporary brain reading technologies promise to provide the possibility to decode and interpret mental states and processes. Brain reading could have numerous societally relevant implications. In particular, the private character of mind might be affected, generating ethical and legal concerns. This paper aims at equipping ethicists and policy makers with conceptual tools to support an evaluation of the potential applicability and the implications of current and near future brain reading technology. We start with clarifying the concepts of mind reading and (...) brain reading, and the different kinds of mental states that could in principle be read. Subsequently, we devise an evaluative framework that is composed of five criteria-accuracy, reliability, informativity, concealability and enforceability-aimed at enabling a clearer estimation of the degree to which brain reading might be realistically deployed in contexts where mental privacy could be at stake. While accuracy and reliability capture how well a certain method can access mental content, informativity indicates the relevance the obtainable data have for practical purposes. Concealability and enforceability are particularly important for the evaluation of concerns about potential violations of mental privacy and civil rights. The former concerns the degree with which a brain reading method can be concealed from an individual’s perception or awareness. The latter regards the extent to which a method can be used against somebody’s will. With the help of these criteria, stakeholders can orient themselves in the rapidly developing field of brain reading. (shrink)

It is argued that, of the three distinct approaches usually adhered to in discussions of this controversy, none will produce an adequate reconstruction of the episode. The philosophical-methodological type of approach leads to a glossing over of the intricacies of deductive and inductive procedures inhering in the writings of both antagonists (§ 1). The metaphysical approach leads to oversimplification as to the thinking of either scientist on the problem of the continuous or discontinuous character of Nature(§ 2). The epistemological (theory (...) of knowledge) type of approach, finally, leads authors to posit a Linnaean realism vs. a Buffonian nominalism, whereas the true position was much more complex than what transpires(§ 3). The paper proceeds, therefore, to provide a novel reconstruction of this wellknown controversy (§ 4-5), concentrating on the differing choices made by the two naturalists in their work of botanical or zoological classification : thus seeking to show that the clash came about because Buffon rejected the rigid principle of character subordination put forward by Linnaeus, and, on a more general level, because the two protagonists were proceeding from deeply diverging views of what natural history, and what the naturalist's function, should be. (shrink)

We propose that sleep is linked to synaptic homeostasis. Specifically, we propose that: (1) Wakefulness is associated with synaptic potentiation in cortical circuits; (2) synaptic potentiation is tied to the homeostatic regulation of slow wave activity; (3) slow wave activity is associated with synaptic downscaling; and (4) synaptic downscaling is tied to several beneficial effects of sleep, including performance enhancement.

There are two main meanings in Kant’s concept of moral certainty (moralische Gewissheit, certitudo moralis): first, it applies to the kind of certainty embodied in rational faith in the existence of God and a future life; second, it applies to the conscientiousness (Gewissenhaftigkeit) required of an agent in the practice of moral judgement. Despite the growing attention to Kant’s theory of conscience and his concept of conscientiousness, this article is the first to discuss ‘moral certainty’ as the aim of ‘conscientiousness’ (...) and to highlight the relevance of both notions in regard to moral education and the purposes of Kant’s ethical doctrines of method. (shrink)

A Nobel Prize-winning scientist and a leading brain researcher show how the brain creates conscious experience.

A constructivisation of the cut-elimination proof for sequent calculi for classical, intuitionistic and minimal infinitary logics with geometric rules—given in earlier work by the second author—is presented. This is achieved through a procedure where the non-constructive transfinite induction on the commutative sum of ordinals is replaced by two instances of Brouwer’s Bar Induction. The proof of admissibility of the structural rules is made ordinal-free by introducing a new well-founded relation based on a notion of embeddability of derivations. Additionally, conservativity for (...) classical over intuitionistic/minimal logic for the seven (finitary) Glivenko sequent classes is here shown to hold also for the corresponding infinitary classes. (shrink)

In this paper, I assess critically the recent debate on corrective duties across moral and legal philosophy. Two prominent positions have emerged: the Kantian rights-based view (holding that what triggers corrections is a failure to respect others' right to freedom) and the so-called continuity view (correcting means attempting to do what one was supposed to do before). Neither position, I try to show, offers a satisfactory explanation of the ground (why correct?) and content (how to correct?) of corrective duties. In (...) the final section, I suggest that it is probably better to restrict the label “corrective duties” to duties generated by interpersonal wronging. (shrink)

Feminist thinkers have commonly interpreted Edith Stein’s “dual anthropology” as a form of essentialism and difference feminism. For them, men and women have (or should have) different functions and capabilities. The article argues against this traditional account. Starting from two distinct criticisms of difference feminism – that of Judith Butler and that of Martha Nussbaum – it claims that the best way to read Stein’s position is to consider it a liberal feminism, for the emphasis that she puts on the (...) uniqueness of every single human being. (shrink)

Two problems about rights have received so far little attention. One is the problem of identifying a general value in the practice of rights. The second is to see when, if at all, rights violations wrong the right-holder, in a morally significant sense. In the present essay, I address the first question by investigating the second. I first show that if we commit to the two ideas, common in the contemporary philosophy of rights, that claim-rights always correlate with directed duties (...) and that rights aspire to protect interests of the right-holder, we make it hard to explain why rights violations, in general, wrong right-holders. In the final section, I present what I see as a promising solution to the puzzle. I describe a particular social environment (the society of equals) where interacting with others through rights is indeed valuable because respecting rights communicates that one takes seriously others’ equal moral status. In such a society and only in such a society, I conclude, moral agents are required to treat all rights violations as wrongs perpetrated against the right-holder. (shrink)