Human security is a multidimensional concept that has been a cornerstone of Japanese development co-operation for more than a decade. At the heart of security is the idea of protection or insurance against downside risk.1, 2 Three distinct questions arise from the concept of human security. First, protection of what? Second, insurance against what? And, third, security for whom? The first question relates to the specification of what is to be protected. The definition of human security offered by the Commission on Human Security 3 is: “to protect the vital core of all human lives in ways that enhance human freedoms and human fulfilment”. The core of a person's life is closely concerned with the person's wellbeing and agency, which is best viewed in terms of his or her “capability” to achieve alternative “beings and doings”. 4 In this context, health assumes central importance for two reasons: it is directly constitutive of a person's wellbeing; and it enables a person to function as an agent—that is, to pursue the various goals and projects in life that he or she has reason to value. This view deploys the notion of well-functioning, but it is not grounded in notions of economic welfare that are based on utility or income. It is, rather, an agency-centred view of a person, for whom ill health restricts the scope of human agency. Since our ability to do things typically depends on our being alive, the capability to lead a long and healthy life must itself be regarded as a basic capability. The second question related to human security is insurance against what. Here the concern is to insure against falling below an adequate threshold of human capabilities—in the case of a person's health, a minimum acceptable level. The probability of falling below a minimum threshold depends on both how vulnerable a person is—the degree of downside risk the person faces—and how much above the threshold he or she is in the relevant dimension. 1 The extreme case of insecurity is certainty of being below a specified threshold, and the absence of any chance of avoiding that fate. Threats to human security can arise, for example, from natural disasters and environmental catastrophes—such as the 2011 earthquake and tsunami in Japan, and the consequent leakage of radioactive material from the Fukushima Daiichi nuclear plant. They can arise from disease outbreaks such as HIV/AIDS, severe acute respiratory syndrome and drug-resistant tuberculosis; from personal accidents and illness; from economic downturns as in the Asian financial crisis of 1997–98; and from various other hazards that people face.3, 5, 6 The vulnerability of a person to such risks will depend on his or her individual circumstances—including location, epidemiological environment, health status, and economic position. A person's health is affected by health care and various other determinants—eg, socioeconomic, behavioural, occupational, and dietary. But access to appropriate health care is also a vital factor in protecting a person from the risk of ill health, and especially of catastrophic ill health. Comprehensive health care is thus important both in promotion of health and in response to health crises. Without health insurance, a severe medical crisis that threatens survival, for example, can have disastrous financial implications—that can affect human security in many other dimensions. The third question concerns security for whom—the entire population or a subset of it? Universalism can be defended through a variety of different approaches, which all invoke equity, fairness, or impartiality in some form or other. For instance, we can appeal to impartiality through the device of Rawls's “veil of ignorance” in the “original position”. 7 Behind the veil of ignorance, I do not know who I will turn out to be and what serious illness or health threat I might encounter, which could require extensive medical attention. Given this uncertainty, the institutional arrangement for health care I am likely to favour is one that ensures comprehensive coverage for all. The concept of human security has wide reach and includes multiple concerns. A major concern is protection of people's health, for which comprehensive health coverage for all is an essential requirement. Universal health insurance thus contributes directly to furthering human security. This implication is as valid for Japan as for other countries in the world. The tragic events of, and responses to, the earthquake of 2011 are a powerful reminder of Japan's concern for human security. In the past, several distinguished politicians, civil servants, and academics in Japan have drawn on and developed the concept of human security—including former Prime Minister Keizo Obuchi, Japan International Cooperation Agency President Sadako Ogata, global health expert Keizo Takemi, and Japan Center for International Exchange President Tadashi Yamamoto.3, 8, 9, 10, 11 Indeed, universal health coverage in Japan, now in existence for 50 years, is indicative of the priority that Japan accords to human security. Over the decades, Japan has also undertaken policies to advance human security in other dimensions, such as basic education, social protection, and economic safety nets. Internationally, Japan has used the concept of human security to guide assistance to developing countries through bilateral aid and multilateral policies. The range and reach of the idea of human security are extensive, as Japanese actions have shown. A central manifestation of these actions is the country's commitment to universal health insurance. © 2012 Reuters 2012 Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. 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