The term privacy is used frequently in ordinary language as well as in philosophical, political and legal discussions, yet there is no single definition or analysis or meaning of the term. The concept of privacy has broad historical roots in sociological and anthropological discussions about how extensively it is valued and preserved in various cultures. Moreover, the concept has historical origins in well known philosophical discussions, most notably Aristotles distinction between the public sphere of political activity and the private sphere associated with family and domestic life. Yet historical use of the term is not uniform, and there remains confusion over the meaning, value and scope of the concept of privacy.

Early treatises on privacy appeared with the development of privacy protection in American law from the 1890s onward, and privacy protection was justified largely on moral grounds. This literature helps distinguishdescriptiveaccounts of privacy, describing what is in fact protected as private, fromnormativeaccounts of privacy defending its value and the extent to which it should be protected. In these discussions some treat privacy as aninterestwith moral value, while others refer to it as a moral or legalrightthat ought to be protected by society or the law. Clearly one can be insensitive to anothers privacy interests without violating any right to privacy, if there is one.

There are several skeptical and critical accounts of privacy. According to one well known argument there is no right to privacy and there is nothing special about privacy, because any interest protected as private can be equally well explained and protected by other interests or rights, most notably rights to property and bodily security (Thomson, 1975). Other critiques argue that privacy interests are not distinctive because the personal interests they protect are economically inefficient (Posner, 1981) or that they are not grounded in any adequate legal doctrine (Bork, 1990). Finally, there is the feminist critique of privacy, that granting special status to privacy is detrimental to women and others because it is used as a shield to dominate and control them, silence them, and cover up abuse (MacKinnon, 1989).

Nevertheless, most theorists take the view that privacy is a meaningful and valuable concept. Philosophical debates concerning definitions of privacy became prominent in the second half of the twentieth century, and are deeply affected by the development of privacy protection in the law. Some defend privacy as focusing on control over information about oneself (Parent, 1983), while others defend it as a broader concept required for human dignity (Bloustein, 1964), or crucial for intimacy (Gerstein, 1978; Inness, 1992). Other commentators defend privacy as necessary for the development of varied and meaningful interpersonal relationships (Fried, 1970, Rachels, 1975), or as the value that accords us the ability to control the access others have to us (Gavison, 1980; Allen, 1988; Moore, 2003), or as a set of norms necessary not only to control access but also to enhance personal expression and choice (Schoeman, 1992), or some combination of these (DeCew, 1997). Discussion of the concept is complicated by the fact that privacy appears to be something we value to provide a sphere within which we can be free from interference by others, and yet it also appears to function negatively, as the cloak under which one can hide domination, degradation, or physical harm to women and others.

This essay will discuss all of these topics, namely, (1) the historical roots of the concept of privacy, including the development of privacy protection in tort and constitutional law, and the philosophical responses that privacy is merely reducible to other interests or is a coherent concept with fundamental value, (2) the critiques of privacy as a right, (3) the wide array of philosophical definitions or defenses of privacy as a concept, providing alternative views on the meaning and value of privacy (and whether or not it is culturally relative), as well as (4) the challenges to privacy posed in an age of technological advance. Overall, most writers defend the value of privacy protection despite the difficulties inherent in its definition and its potential use to shield abuse. A contemporary collection of essays on privacy provides strong evidence to support this point (Paulet al., 2000). The contributing authors examine various aspects of the right to privacy and its role in moral philosophy, legal theory, and public policy. They also address justifications and foundational arguments for privacy rights.

1.2 The Constitutional Right to Privacy

2.2 Posners Economic Critique

2.4 The Feminist Critique of Privacy

3. Views on the Meaning and Value of Privacy

3.1 Privacy and Control over Information

3.4 Privacy and Social Relationships

4.1 The Social dimension of Privacy

4.2 Privacy and Conflicts with Other Values

Aristotles distinction between the public sphere of politics and political activity, thepolis, and the private or domestic sphere of the family, theoikos, as two distinct spheres of life, is a classic reference to a private domain. The public/private distinction is also sometimes taken to refer to the appropriate realm of governmental authority as opposed to the realm reserved for self-regulation, along the lines described by John Stuart Mill in his essay,On Liberty. Furthermore, the distinction arises again in Lockes discussion of property in hisSecond Treatise on Government. In the state of nature all the worlds bounty is held in common and is in that sense public. But one possesses oneself and ones own body, and one can also acquire property by mixing ones labor with it, and in these cases it is ones private property. Margaret Mead and other anthropologists have demonstrated the ways various cultures protect privacy through concealment, seclusion or by restricting access to secret ceremonies (Mead, 1949). Alan Westin (1967) has surveyed studies of animals demonstrating that a desire for privacy is not restricted to humans. However, what is termed private in these multiple contexts varies. Privacy can refer to a sphere separate from government, a domain inappropriate for governmental interference, forbidden views and knowledge, solitude, or restricted access, to list just a few.

More systematic written discussion of the concept of privacy is often said to begin with the famous essay by Samuel Warren and Louis Brandeis titled The Right to Privacy (Warren and Brandeis, 1890). Citing political, social, and economic changes and a recognition of the right to be let alone they argued that existing law afforded a way to protect the privacy of the individual, and they sought to explain the nature and extent of that protection. Focusing in large part on the press and publicity allowed by recent inventions such as photography and newspapers, but referring as well to violations in other contexts, they emphasized the invasion of privacy brought about by public dissemination of details relating to a persons private life. Warren and Brandeis felt a variety of existing cases could be protected under a more general right to privacy which would protect the extent to which ones thoughts, sentiments, and emotions could be shared with others. Urging that they were not attempting to protect the items produced, or intellectual property, but rather the peace of mind attained with such protection, they said the right to privacy was based on a principle of inviolate personality which was part of a general right of immunity of the person, the right to ones personality (Warren and Brandeis 1890, 195, 215). The privacy principle, they believed, was already part of common law and the protection of ones home as ones castle, but new technology made it important to explicitly and separately recognize this protection under the name of privacy. They suggested that limitations of the right could be determined by analogy with the law of slander and libel, and would not prevent publication of information about public officials running for office, for example. Warren and Brandeis thus laid the foundation for a concept of privacy that has come to be known as control over information about oneself.

Although the first cases after the publication of their paper did not recognize a privacy right, soon the public and both state and federal courts were endorsing and expanding the right to privacy. In an attempt to systematize and more clearly describe and define the new right of privacy being upheld in tort law, William Prosser wrote in 1960 that what had emerged were four different interests in privacy. Not claiming to be providing an exact definition, and admitting that there had been confusion and inconsistencies in the development of privacy protection in the law, Prosser nevertheless described the four rather definite privacy rights as follows:

Intrusion upon a persons seclusion or solitude, or into his private affairs.

Public disclosure of embarrassing private facts about an individual.

Publicity placing one in a false light in the public eye.

Appropriation of ones likeness for the advantage of another (Prosser 1960, 389).

Prosser noted that the intrusion in the first privacy right had expanded beyond physical intrusion, and pointed out that Warren and Brandeis had been concerned primarily with the second privacy right. Nevertheless, Prosser felt that both real abuses and public demand had led to general acceptance of these four types of privacy invasions. On his view, answers to three main questions were at the time as yet unclear: (i) whether appearance in public implied forfeiture of privacy, (ii) whether facts part of a public record could still be private, and (iii) whether a significant lapse of time affected the privacy of revelations. Note that Warren and Brandeis were writing their normative views about what they felt should be protected under the rubric of privacy, whereas Prosser was describing what courts had in fact protected in the 70 years following publication of the Warren and Brandeis paper. Thus it is not surprising that their descriptions of privacy differ. Because the Supreme Court has been explicit in ruling that privacy is a central reason for Fourth Amendment protection, privacy as control over information about oneself has come to be viewed by many as also including protection against unwarranted searches, eavesdropping, surveillance, and appropriation and misuses of ones communications. Thomas Nagel (2002) gives a more contemporary discussion of privacy, concealment, publicity and exposure.

Despite the well-established protection of tort privacy to control information about oneself in the courts, and the almost universal acceptance of the value of informational privacy by philosophers and the populace, Abraham L. Newman (2008) and others have persuasively argued that the United States (US), and multiple countries in Asia, has developed a limited system of privacy protection that focuses on self-regulation within industry and government so that personal information is often readily available. In contrast, the European Union (EU) and others have adopted an alternative vision highlighting consumer protection and individual privacy against the economic interests of firms and public officials. This latter model developed from comprehensive rules about data privacy enacted in the EUs Data Protection Directive in 1995, now adopted in some form by all 27 EU nations. European-style privacy protection regulations have spread rapidly across the industrial world, with the United States as a major exception, and have transformed and led the global privacy debate, while the US has relied on a more laissez-faire mentality about protection of personal information and a patchwork of privacy guidelines. This patchwork includes privacy regulations on student records, video rentals, the Childrens Online Privacy Protection Act (COPPA, 2000), the Health Insurance Portability and Accountability Act (HIPPA, 2006) and more.

The European Union empowered individual privacy commissioners or group agencies that had technical expertise, were given governmental authority, and were able to form political coalitions to lobby successfully for enhanced individual privacy protection, requiring that personal information not be collected or used for purposes other than those initially intended without individual consent, and so on. This contrasts sharply with the American approach allowing entities such as insurance companies and employers ample access to personal information not covered by the separate privacy guidelines, given a lack of governmental support for more comprehensive privacy legislation and a more fragmented political system. The US has generally stood behind efficiency arguments that business and government need unfettered access to personal data to guarantee economic growth and national security, whereas the EU has sent a coherent signal that privacy has critical value in a robust information society because citizens will only participate in an online environment if they feel their privacy is guaranteed against ubiquitous business and government surveillance.

In 1965 a quite different right to privacy, independent of informational privacy and the Fourth Amendment, was recognized explicitly by the Supreme Court. It is now commonly called the constitutional right to privacy. The right was first announced in theGriswold v. Connecticut(381 U.S. 479) case, which overturned convictions of the Director of Planned Parenthood and a doctor at Yale Medical School for dispersing contraceptive related information, instruction, and medical advice to married persons. The constitutional right to privacy was described by Justice William O. Douglas as protecting a zone of privacy covering the social institution of marriage and the sexual relations of married persons. Despite controversy over Douglas opinion, the constitutional privacy right was soon cited to overturn a ban against interracial marriage, to allow individuals to possess obscene matter in their own homes, and to allow distribution of contraceptive devices to individuals, both married and single. The most famous application of this right to privacy was as one justification of abortion rights defended in 1973 inRoe v. Wade(410 U.S. 113) and subsequent decisions on abortion. While Douglas vaguely called it a penumbral right emanating from the Constitution, and the Court has been unable to clearly define the right, it has generally been viewed as a right protecting ones individual interest in independence in making certain important and personal decisions about ones family, life and lifestyle. Which personal decisions have been protected by this privacy right has varied depending on the makeup of the Court. In 1986 inBowers v. Hardwick(478 U.S. 186) privacy was not held to cover a ban on anti-sodomy laws in Georgia, despite the intimate sexual relations involved.

Criticism of the constitutional right to privacy has continued, particularly in the popular press,Roe v. Wademay be in jeopardy, and many viewed theBowersdecision as evidence of the demise of the constitutional right to privacy. Yet in 2003 inLawrence v. Texas(538 U.S. 918), the Supreme Court ruled 54 that a Texas statute making it a crime for two people of the same sex to engage in certain intimate behavior violated the guarantee of equal protection and vital interests in liberty and privacy protected by the due process clause of the Constitution, thus overrulingBowers v. Hardwick. Jean L. Cohen (2002) gives a theoretical defense of this inclusive view of the constitutional right to privacy. She defends a constructivist approach to privacy rights and intimacy, arguing that privacy rights protect personal autonomy and that a constitutionally protected right to privacy is indispensable for a modern conception of reason and her interpretation of autonomy. Currently many non U.S. countries protect interests in what is now called constitutional privacy, without the controversy that is somewhat more common in the U.S. For example, constitutional privacy has been used in the U.S. to strike down anti-sodomy laws, and to protect individual choice of ones marriage partner. In Europe many countries now protect same sex marriage, such as the Netherlands for over 10 years and more recently Germany since 2017.

One way of understanding the growing literature on privacy is to view it as divided into two main categories, which we may callreductionismandcoherentism. Reductionists are generally critical of privacy, while coherentists defend the coherent fundamental value of privacy interests. Ferdinand Schoeman (1984) introduced somewhat different terminology which makes it easier to understand this distinction. According to Schoeman, a number of authors have believed

there is something fundamental, integrated, and distinctive about the concerns traditionally grouped together under the rubric of privacy issues. In opposing this position, some have argued that the cases labeled privacy issues are diverse and disparate, and hence are only nominally or superficially connected. Others have argued that when privacy claims are to be defended morally, the justifications must allude ultimately to principles which can be characterized quite independently of any concern with privacy. Consequently, the argument continues, there is nothing morally distinctive about privacy. I shall refer to the position that there is something common to most of the privacy claims as the coherence thesis. The position that privacy claims are to be defended morally by principles that are distinctive to privacy I shall label the distinctiveness thesis.

Theorists who deny both the coherence thesis and the distinctiveness thesis argue that in each category of privacy claims there are diverse values at stake of the sort common to many other social issues and that these values exhaust privacy claims. The thrust of this complex position is that we could do quite well if we eliminated all talk of privacy and simply defended our concerns in terms of standard moral and legal categories (Schoeman 1984, 5).

These latter theorists, who reject both Schoemans coherence thesis and distinctiveness thesis, may be referred to asreductionists, for they view what are called privacy concerns as analyzable or reducible to claims of other sorts, such as infliction of emotional distress or property interests. They deny that there is anything useful in considering privacy as a separate concept. They conclude, then, that there is nothing coherent, distinctive or illuminating about privacy interests.

On the other side, more theorists have argued that there is something fundamental and distinctive and coherent about the various claims that have been called privacy interests. On this view, privacy has value as a coherent and fundamental concept, and most individuals recognize it as a useful concept as well. Those who endorse this view may be calledcoherentists. Nevertheless, it is important to recognize that coherentists have quite diverse, and sometimes overlapping, views on what it is that is distinctive about privacy and what links diverse privacy claims.

Probably the most famous reductionist view of privacy is one from Judith Jarvis Thomson (1975). Noting that there is little agreement on what privacy is, Thomson examines a number of cases that have been thought to be violations of the right to privacy. On closer inspection, however, Thomson believes all those cases can be adequately and equally well explained in terms of violations of property rights or rights over the person, such as a right not to be listened to. Ultimately the right to privacy, on Thomsons view, is merely a cluster of rights. Those rights in the cluster are always overlapped by, and can be fully explained by, property rights or rights to bodily security. The right to privacy, on her view, is derivative in the sense that there is no need to find what is common in the cluster of privacy rights. Privacy is derivative in its importance and justification, according to Thomson, as any privacy violation is better understood as the violation of a more basic right. Numerous commentators provide strong arguments against Thomsons critique (Scanlon, 1975; Inness, 1992).

Richard Posner (1981) also presents a critical account of privacy, arguing that the kinds of interests protected under privacy are not distinctive. Moreover, his account is unique because he argues that privacy is protected in ways that are economically inefficient. With respect to information, on Posners view privacy should only be protected when access to the information would reduce its value (e.g. allowing students access to their letters of recommendation make those letters less reliable and thus less valuable, and hence they should remain confidential or private). Focusing on privacy as control over information about oneself, Posner argues that concealment or selective disclosure of information is usually to mislead or manipulate others, or for private economic gain, and thus protection of individual privacy is less defensible than others have thought because it does not maximize wealth. In sum, Posner defends organizational or corporate privacy as more important than personal privacy, because the former is likely to enhance the economy.

Another strong critic of privacy is Robert Bork (1990), whose criticism is aimed at the constitutional right to privacy established by the Supreme Court in 1965. Bork views theGriswold v. Connecticutdecision as an attempt by the Supreme Court to take a side on a social and cultural issue, and as an example of bad constitutional law. Borks attack is focused on Justice William O. Douglas and his majority opinion inGriswold. Borks major point is that Douglas did not derive the right to privacy from some pre-existing right or from natural law, but merely created a new right to privacy with no foundation in the Constitution or Bill of Rights. Bork is correct that the word privacy never appears in those documents. Douglas had argued, however, that the right to privacy could be seen to be based on guarantees from the First, Third, Fourth, Fifth, and Ninth Amendments. Taken together, the protections afforded by these Amendments showed that a basic zone of privacy was protected for citizens, and that it covered their ability to make personal decisions about their home and family life. In contrast, Bork argues i) that none of the Amendments cited covered the case before the Court, ii) that the Supreme Court never articulated or clarified what the right to privacy was or how far it extended, and he charges iii) that the privacy right merely protected what a majority of justices personally wanted it to cover. In sum, he accuses Douglas and the Court majority of inventing a new right, and thus overstepping their bounds as judges by making new law, not interpreting the law. Borks views continue to be defended by others, in politics and in the popular press.

Theorists including William Parent (1983) and Judith Thomson (1975) argue that the constitutional right to privacy is not really a privacy right, but is more aptly described as a right to liberty. Other commentators believe, to the contrary, that even if Douglas opinion is flawed in its defense, using vague language about a penumbral privacy right emanating from the Constitution and its Amendments, there is nevertheless a historically and conceptually coherent notion of privacy, distinct from liberty, carved out by the constitutional privacy cases (Inness, 1992; Schoeman, 1992; Johnson, 1994; DeCew, 1997).

In response to Borks complaint that constitutional privacy protection is not at all about privacy but only concerns liberty or autonomy, it has been successfully argued that while we have multiple individual liberties such as freedom of expression, many do not seem to be about anything particularly personal or related to the types of concerns we might be willing and able to see as privacy issues. If so, then liberty is a broader concept than privacy and privacy issues and claims are a subset of claims to liberty. In support of this view, philosophical and legal commentators have urged that privacy protects liberty, and that privacy protection gains for us the freedom to define ourselves and our relations to others (Allen, 2011; DeCew, 1997; Reiman, 1976, 2004; Schoeman, 1984, 1992).

A moving account supporting this viewunderstanding privacy as a necessary and an indispensable condition for freedomcomes from literature, here a quotation from Milan Kundera.

But one day in 1970 or 1971, with the intent to discredit Prochazka, the police began to broadcast these conversations [with Professor Vaclav Cerny, with whom he liked to drink and talk] as a radio serial. For the police it was an audacious, unprecedented act. And, surprisingly: it nearly succeeded; instantly Prochazka

discredited: because in private, a person says all sorts of things, slurs friends, uses coarse language, acts silly, tells dirty jokes, repeats himself, makes a companion laugh by shocking him with outrageous talk, floats heretical ideas hed never admit in public, and so forth. Of course, we all act like Prochazka, in private we bad-mouth our friends and use coarse language; that we act different in private than in public is everyones most conspicuous experience, it is the very ground of the life of the individual; curiously, this obvious fact remains unconscious, unacknowledged, forever obscured by lyrical dreams of the transparent glass house, it is rarely understood to be the value one must defend beyond all others. Thus only gradually did people realize (though their rage was all the greater) that the real scandal was not Prochazkas daring talk but the rape of his life; they realized (as if by electric shock) that private and public are two essentially different worlds and that respect for that difference is the indispensable condition, the sine qua non, for a man to live free; that the curtain separating these two worlds is not to be tampered with, and that curtain-rippers are criminals. And because the curtain-rippers were serving a hated regime, they were unanimously held to be particularly contemptible criminals. (Kundera, 1984, 261)

It is not difficult to see the analogies between Kunderas scenario and electronic surveillance and street cameras common in society today. There is more detailed evidence that privacy and liberty are distinct concepts, that liberty is a broader notion, and that privacy is essential for protecting liberty. We have many forms of liberty that do not appear to have anything to do with what we might value as private and inappropriate for government intervention for personal reasons. The right to travel from state to state without a passport, for example, seems to be a freedom far different from freedom to make decisions about personal and intimate concerns about ones body such as contraception use, abortion choice, sterilization (Buck v. Bell, 274 U.S. 200, 1927) and vasectomies (Skinner v, Oklahoma316 U.S. 535, 1942, striking down a statute mandating sterilizations for those who commit three felonies). It is clear that the U.S. Supreme Court has recognized this by saying that the constitutional privacy cases are about a second interest in privacy, namely an individual interest in making certain kinds of important decisions (Whalen v. Roe, 429 U.S. 589, 1977).

There is no single version of the feminist critique of privacy, yet it can be said in general that many feminists worry about the darker side of privacy, and the use of privacy as a shield to cover up domination, degradation and abuse of women and others. Many tend to focus on the private as opposed to the public, rather than merely informational or constitutional privacy. If distinguishing public and private realms leaves the private domain free from any scrutiny, then these feminists such as Catharine MacKinnon (1989) are correct that privacy can be dangerous for women when it is used to cover up repression and physical harm to them by perpetuating the subjection of women in the domestic sphere and encouraging nonintervention by the state. Jean Bethke Elshtain (1981, 1995) and others suggest that it appears feminists such as MacKinnon are for this reason rejecting the public/private split, and are, moreover, recommending that feminists and others jettison or abandon privacy altogether. But, Elshtain points out, this alternative seems too extreme.

A more reasonable view, according to Anita Allen (1988), is to recognize that while privacy can be a shield for abuse, it is unacceptable to reject privacy completely based on harm done in private. A total rejection of privacy makes everything public, and leaves the domestic sphere open to complete scrutiny and intrusion by the state. Yet women surely have an interest in privacy that can protect them from state imposed sterilization programs or government imposed drug tests for pregnant women mandating results sent to police, for instance, and that can provide reasonable regulations such as granting rights against marital rape. Thus collapsing the public/private dichotomy into a single public realm is inadequate. What puzzles feminists is how to make sense of an important and valuable notion of privacy that provides them a realm free from scrutiny and intervention by the state, without reverting to the traditional public/private dichotomy that has in the past relegated women to the private and domestic sphere where they are victims of abuse and subjection. The challenge is to find a way for the state to ta