Libertarianism is a controversial political theory. But it is often presented as a resting upon a simple, indeed commonsense, moral principle. The libertarian “Nonaggression Principle” (NAP) prohibits aggression against the persons or property of others, and it is on this basis that the libertarian opposition to redistributive taxation, legal paternalism, and perhaps even the state itself is thought to rest. This essay critically examines the NAP and the extent to which it can provide support for libertarian political theory. It identifies two problems with existing libertarian appeals to the NAP. First, insofar as libertarians employ a moralized understanding of aggression, their principle is really about the protection of property rights rather than the prohibition of aggression. Second, the absolutist prohibition on aggression, which libertarians typically endorse and which is necessary to generate strongly libertarian conclusions, is grossly implausible. The essay concludes by setting forth a version of the NAP that does not suffer from these problems. It argues that this more moderate and defensible version of the NAP still has important libertarian implications, but that a full defense of libertarianism cannot rely upon appeals to nonaggression alone.

In this essay, I explore ethical considerations that might arise from the use of collaborative filtering algorithms on dating apps. Collaborative filtering algorithms can predict the preferences of a target user by looking at the past behavior of similar users. By recommending products through this process, they can influence the news we read, the movies we watch, and more. They are extremely powerful and effective on platforms like Amazon and Google. Recommender systems on dating apps are likely to group people by race, since they exhibit similar patterns of behavior: users on dating platforms seem to segregate themselves based on race, exclude certain races from romantic and sexual consideration (except their own), and generally show a preference for white men and women. As collaborative filtering algorithms learn from these patterns to predict preferences and build recommendations, they can homogenize the behavior of dating app users and exacerbate biased sexual and romantic behavior.

Liberal egalitarian political philosophers have often argued that private property is a legal convention dependent on the state and that complaints about taxation from entitlement theorists are therefore based on a conceptual mistake. But our capacity to grasp and use property concepts seems too embedded in human nature for this to be correct. This essay argues that many standard arguments that property is constitutively a legal convention fail, but that the opposition between conventionalists and natural rights theorists is outmoded. In doing this, the essay draws on recent literature in evolutionary biology and psychology. Even though modern property in a complex society involves legal conventions, those conventions should be sensitive to our natural dispositions concerning ownership.

Biotechnology surpasses even computer technology in predictions of its potential for revolutionary effects on humankind. It includes agribusiness (genetically engineered plants, animals, hormones, etc.) and phar-maceuticals (diagnostics, genetic therapies, etc.). The U.S. government began investing heavily in biotechnology research in the 1980s, and by 1987 had spent approximately $2.7 billion to support research and development (R and D), including $150 million for agricultural biotechnology. The approximately sixty U.S. biotechnology companies invested $3.2 billion in R and D in 1991 alone, with a total of more than $10 billion spent since the industry began in the late 1970s.

The over-exploitation of commonly-held resources is typically analyzed as an instance of market failure that calls for legislation to internalize the social costs that private activities impose on the environment. In this article, I argue that to the extent that this analysis ignores the regulatory effect of the common law, it is unsound. In The Tragedy of the Commons, Garret Hardin points out that there are two solutions to the tragedy: privatize the resource or restrict access to it. Environmental legislation is a means restricting access to the commons. The evolutionary development of common law is a means of privatizing the commons. These represent alternative methods of environmental regulation. Proper public policy analysis requires a comparative assessment of the efficacy of these methods for resolving any particular environmental problem. In many, if not most cases, such an assessment will show common law regulation to be superior to environmental legislation.

Rights-oriented libertarian theory asserts the existence of robust individual rights - including robust rights of property. If these property rights are absolute, then it seems that all taxation is theft. However, it also seems that, if an individual is (faultlessly) in dire straits, it is permissible for him to seize or trespass in order to escape from those straits. It does seem that in this sense property rights are non-absolute. This essay examines what contribution this non-absoluteness of rights makes to the justification of taxation for the sake of rescuing individuals from their dire straits. The essay investigates how dire an individual's circumstances have to be for him to have a dispensation from the normal obligation to respect property. It distinguishes among different dispensations that individuals in dire enough circumstances may have. And it emphasizes how precarious is the path from the premise that sometimes individuals possess one or another of these dispensations to the conclusion that taxation to rescue people from dire straits is justified.

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The existence of the legal profession is something most lawyers take for granted. Lawyers of course do many different things, and lead different sorts of lives, but those who make their living in the law tend to assume, without much reflection, that they have a bond or association of some sort with others who do the same and believe they share something important in common with them. It is not at all clear, however, what this common element is, and the great diversity of tasks that lawyers perform – representing litigants, counseling clients, advising legislators, administering government programs, and deciding cases – can easily make one doubt whether the search for a link leads to anything but empty generalities.

One may, of course, conclude that the main law jobs, as Karl Llewellyn called them, have nothing important in common, and that the legal profession is only a name for a disconnected collection of pursuits with no substance or reality of its own. This is not, however, a very satisfying view, to lawyers at least, and is likely to provoke the quick reply that what lawyers share in common is after all quite easy to discern. All lawyers, regardless of the nature of their work, possess a general knowledge of the law which they have acquired through a specialized program of instruction; laypersons lack such knowledge and it is this, one might argue, which marks the line between those who are lawyers and those who are not and, thus, defines the scope and nature of the profession.

'Tis true governments cannot be supported without great charge, and it is fit everyone who enjoys a share of the protection should pay out of his estate his proportion for the maintenance of it. But still it must be with his own consent, i.e., the consent of the majority giving it either by themselves or their representatives chosen by them. For if any one shall claim a power to lay and levy taxes on the people, by his own authority, and without such consent of the people, he thereby invades the fundamental law of property and subverts the end of government. For what property have I in that which another may by right take when he pleases to himself.

Accusing, condemning, and avenging are part of our daily life. However, a review of many years of literature attempting to analyze our blaming practices suggests that we do not understand very well what we are doing when we judge people culpable for a wrong they have committed. Of course, everyone agrees that, for example, someone deserves censure and punishment when she is guilty of a wrong, and the law has traditionally looked for a mens rea, or “guilty mind,” in order to convict someone of a criminal wrongdoing. But philosophers and legal theorists have found it interestingly difficult to say what mens rea is. For example, noting the way in which we intuitively think people aren't culpable for a crime if they disobey the law by mistake, or under duress, or while insane, theorists such as H.L.A. Hart have tried to define mens rea negatively, as that which an agent has if he is not in what we consider to be an excusing state. But such an approach only circumscribes and does not unravel the central mystery; it also fails to explain why the law recognizes any excusing states as mitigating or absolving one of guilt, much less why all and only the excusing states that are recognized by the law are the right ones. Moreover, the Model Penal Code, which gives a very detailed account of the kinds of mental states which justify criminal conviction, does not tell us (nor was it designed to tell us) why these states of mind (e.g., knowledge, purposiveness, intention, assumption of risk of harm, negligence) are relevant to an assessment of legal guilt.

“Does the existence of unequal social and economic starting points in life nullify capitalism's claims to justice?” Notice is hereby given that this essay's answer to this question is an unequivocal “maybe.” For it is a banal but true claim that everything depends upon what is meant by capitalism, justice and life's starting point. And it is a less banal but no less true claim that their meanings are opaque or controversial or both. In what follows I shall devote little attention to the question of what justice is and shall simply presume that it is best characterized by historical entitlement theory. The last part of the essay discusses the notion of life's starting point and vacillates over what it would mean for one such point to be equal to another. Hence, the bulk of my argument is taken up with exploring what capitalism must be like to conform to historical entitlement theory. And my conclusion will be that, insofar as capitalism respects every person's right of self-ownership, its claims to justice require that no one be denied one type of equal payment – a payment which might be rendered at each life's starting point.

We live in an age of great scientific and technological innovation, and what seemed out of the question or at least very doubtful only a few years ago, today lies almost within our grasp. In no area is this more true than that of human health care, where lifesaving and life-enhancing technologies have given, or have the enormous potential in the not so distant future to give, relief from some of the most terrible human illnesses. On two fronts in particular, xenograft or cross-species transplantation and genetic engineering of animals on behalf of gene therapy in humans, such relief appears very promising, if not actually on the horizon. Certainly, extensive research work on both fronts is underway both in the United States and abroad.

In recent years there has been growing interest in the contrast between Humean theories of property, on the one hand, and Lockean and Rousseauian theories, on the other. The contrast is a broad and abstract one, along the following lines.

One of the most noteworthy features of David Gauthier's rational choice, contractarian theory of morality is its appeal to self-interested rationality. This appeal, however, will undoubtedly be the source of much controversy and criticism. For while self-interestedness is characteristic of much human behavior, it is not characteristic of all such behavior, much less of that which is most admirable. Yet contractarian ethics appears to assume that humans are entirely self-interested. It is not usually thought a virtue of a theory that its assumptions are literally false. What may be said on behalf of the contractarian?

Contemporary critics of the administrative state are right to highlight the dangers of vesting too much power in a centralized bureaucracy removed from popular oversight and accountability. Too often neglected in this literature, however, are the dangers of vesting too little power in a centralized state, which enables dominant groups to further expand their social and economic advantages through decentralized means. This article seeks to synthesize these concerns, understanding them as reflecting the same underlying danger of state capture. It then articulates a set of heuristics for the design of public and administrative institutions, which aim at minimizing the risks of capture from both public and private sources. By following these heuristics, it claims, we can successfully employ the administrative state as a weapon against concentrated private power, rather than allowing it to serve as a tool of dominant groups.

One way to think about capitalism-versus-socialism is to examine the extent to which capitalist economic institutions are compatible with the fulfillment of socialist ideals. The late G. A. Cohen has urged that the two are strongly incompatible. He imagines how it would make sense for friends to organize a camping trip, distills the socialist moral principles that he sees fulfilled in the camping trip model, and observes that these principles conflict with a capitalist organization of the economy. He adds that these principles are ethically attractive, so if it is feasible to organize the economy on the camping trip model, we ought to do so. This essay argues to the contrary that for all that has been said, capitalist economic arrangements might be in the set of institutional arrangements that overall would best fulfill the camping trip principles, and anyway, the principles themselves ought to be rejected, so the question whether or not a capitalist set-up might satisfy these principles should not interest us. The grounds for rejecting the camping trip principles support a form of welfarist consequentialism that denies that equality of distribution of any sort is per se ethically desirable and also denies that liberal freedoms to live as one chooses are per se morally desirable. Equality and freedom should rather be regarded as in the light of possible means (or hindrances) to advancing good for people, fairly distributed.

This essay explores the meaning and normative significance of Locke’s depiction of individuals as proprietors of their own person. I begin by reconsidering the long-standing puzzle concerning Locke’s simultaneous endorsement of divine proprietorship and self-ownership. Befuddlement vanishes, I contend, once we reject concurrent ownership in the same object: while God fully owns our lives, humans are initially sole proprietors of their own person. (Our property rights in our life and body are restricted to possession, use, and usufruct.) Locke employs two conceptions of “personhood”: as expressing legal independence vis-à-vis humans and moral accountability vis-à-vis God. Humans own their person in the first sense. As original proprietors of their own person, individuals are entitled to subject themselves to self-chosen authorities, thereby incurring obligations of obedience. But they may not choose just any authority. Divine ownership of human life delimits personal self-ownership by restricting the ways in which humans can dispose of their persons: we cannot possibly consensually subject ourselves to absolute and arbitrary power. Locke’s rights-forfeiture theory for crime makes slavery and despotism nonetheless potentially rightful conditions. I argue that, paradoxically, divine dominium of human life underpins both the impermissibility of voluntary enslavement and the justifiability of penal slavery. My analysis helps explain why modern Lockean theories of self-ownership that reject Locke’s theological premises have adopted an ambiguous stance toward despotic rule.

In chapter four of Anarchy, State, and Utopia, Robert Nozick raised interesting questions about whether or not it is ever morally acceptable to act against what are agreed to be an individual's natural moral rights. The pursuit of these questions opens up issues concerning the specific content of these individual rights. This essay explores Nozick's questions by posing examples and using our considered responses to them to specify the shape of individual rights. The exploration provisionally concludes that a conception of individual moral rights quite different from Nozick's looks attractive and merits further development.

This paper argues that the occurrence of a non-native species, such as purple loosestrife, on one's property does not constitute a nuisance in the context of background principles of common law. No one is injured by it. The control of non-native species, such as purple loosestrife, does not constitute a compelling public interest, moreover, but represents primarily the concern of an epistemic community of conservation biologists and ecologists. This paper describes a history of cases in agricultural law that establish that a public authority may enter private property to destroy a tree or other species but only to protect a compelling public interest, such as the apple industry in Virginia or the citrus industry in Florida, and only if it pays all the costs including just compensation. The paper argues a fortiori that if a public authority enters private property to control non-native or “invasive” species it must pay all the costs and indemnify the owner—contrary to what many state laws contemplate and the Environmental Law Institute recommends.

If I lead a life of virtue, that may well be good for you. But will it also be good for me? The idea that it will—or even must—is an ancient one, and its appeal runs deep. For if this idea is correct then we can provide everyone with a good reason—arguably the best reason—for being virtuous. However, for all the effort which has been invested in defending the idea, by some of the best minds in the history of philosophy, it remains unproven. Worse, in this skeptical age hardly anyone really believes it. I don't really believe it either, at least not in its strongest forms, but I think that the question is nonetheless worth examining. Even if we cannot show that virtue and self-interest coincide, we can at least measure the breadth of the gap between them.

We are well served, both practically and morally, by ethical diversity, by living in a community whose members have values and priorities that are, at a habit-forming, action-guiding level, often different from our own. Of course, unchecked ethical diversity can lead to disaster, to chaos and conflict. We attempt to avoid or mitigate such conflict by articulating general moral and political principles, and developing the virtues of acting on those principles. But as far as leading a good life — the life that best suits what is best in us — goes, it is not essential that we agree on the interpretations of those common principles, or that we are committed to them, by some general act of the will. What matters is that they form our habits and institutions, so that we succeed in cooperating practically, to promote the state of affairs that realizes what we each prize. People of different ethical orientations can — and need to — cooperate fruitfully in practical life while having different interpretations and justifications of general moral or procedural principles. Indeed, at least some principles are best left ambiguous, and some crucial moral and ethical conflicts are best understood, and best arbitrated, as failures of practical cooperation rather than as disagreements about the truth of certain general propositions or theories.

This way of construing ethical conflict and cooperation carries political consequences. It appears to make the task of resolving ethical conflicts more modest and, perhaps, easier to accomplish. But it raises formidable problems about how to design the range of educative institutions that bridge public and private life.