The sixth chapter provides a deeper exploration of probabilistic models, building upon concepts encountered earlier in the text. The chapter illustrates how to construct diverse models, particularly by employing the notion of conditional independence. It also outlines standard methods for estimating parameters and hidden states, as well as techniques for sampling. The chapter concludes by discussing and implementing applications such as Kalman filtering and Gibbs sampling. The chapter covers a range of topics, including parametric families of probability distributions, maximum likelihood estimation, modeling complex dependencies using conditional independence and marginalization, and applications such as linear-Gaussian models and Kalman filtering.

Irregular war, like war, remains an enduring feature of security studies both as they relate to internal state security and sovereignty as well as to international relations. Irregular war may not always appear to hold political purposes; many today seem driven by religious ideology, but the institution of theocratic governance has a politics of its own. Thus, like regular war, irregular war is subordinate to a political purpose. Whether they occur on the periphery of regular wars or perform roles to keep state competition from escalating into conflict, irregular wars are often intricately tied to their regular counterparts. While two broad theories of counterinsurgency both claim to have prescriptions for winning an irregular fight, one – the good governance approach – is plagued by problems of implementation at the governmental level, and the other – coercion – entails unreasonable brutality against both insurgent and population, often unbefitting a liberal counterinsurgent force.

This chapter introduces the mathematics of data through the example of clustering, a fundamental technique in data analysis and machine learning. The chapter begins with a review of essential mathematical concepts, including matrix and vector algebra, differential calculus, optimization, and elementary probability, with practical Python examples. The chapter then delves into the k-means clustering algorithm, presenting it as an optimization problem and deriving Lloyd's algorithm for its solution. A rigorous analysis of the algorithm's convergence properties is provided, along with a matrix formulation of the k-means objective. The chapter concludes with an exploration of high-dimensional data, demonstrating through simulations and theoretical arguments how the "curse of dimensionality" can affect clustering outcomes.

While the academic study of International Relations immediately following the World Wars was focused on the causes of war and the conditions of peace, the diversification of IR in the mid twentieth century led to the creation of a discrete subfield of security studies. For the remainder of the twentieth century, this subfield focused exclusively on the problem of war – conventional and nuclear – between nation-states. But the end of the Cold War and the proliferation of multiple, opaque, and transnational security risks opened an intellectual space within security studies for a re-envisioning of the analytical approaches to security, as well as to a widening of the agenda. Security was no longer linked exclusively to war but also to a wider range of issues, and security was no longer exclusively conceptualized as the continued existence of the state but applied also to a multitude of actors.

The goal of this chapter is to introduce the crisis of missing and murdered Indigenous women and girls, settler colonialism, and patriarchy. It begins with the story of Abigail Echo-Hawk, the director of the Urban Indian Health Institute, and an enrolled citizen of the Pawnee Nation of Oklahoma. Abigail has advocated for decolonizing data to stop the crisis of missing and murdered Indigenous women and girls in the US. Informed by tribal critical race theory (TribalCrit), this chapter defines and examines popular myths of settler colonialism and patriarchy, two intersecting systems at the root of this crisis and the genocide of Indigenous peoples in the US. Settler colonialism by White Europeans involves seizing land, eradicating Indigenous peoples and culture, and creating a permanent settler society on that territory. Patriarchy is a system of gendered domination that invests men with exclusive rights, authority, and privilege over women. The chapter includes a Food for Thought section on the climate crisis and the Land Back movement. It ends with a discussion of Abigail Echo-Hawk and the importance of stories.

This chapter looks at how energy fits into our understanding of international security as part of the widening of the security agenda. First, we define exactly what energy security means. Then we look at what theories of international security predict around energy security before moving on to a case study of the Middle East as an energy supplier. The chapter rounds out with a look at how the great powers in today’s international system are approaching the energy challenge.

Rational choice theory is a social theory of decision-making that assumes individuals, groups, organizations, and states are strategic actors and thus make rational choices based on their preferences, available information, and the expected outcomes of their actions. The theory is based on the Enlightenment idea that individuals are autonomous and should seek their own self-interest, and that we can determine how an individual should behave by understanding how they might best maximize the utility of their decisions. Game theory is an approach within the rational choice framework that models mathematically the mutual best responses of each player according to their preference orderings.

The concept of human security was first introduced formally in the 1994 UNDP Report and signaled a significant shift of focus from state security to the security of individual human beings and human communities. Unlike the abstract and theoretical debates within academia around that time about deepening and widening the definition of security, the human security approach was born from within the policy world and was policy-oriented. In the thirty years since its introduction, human security has undergone a series of reformulations, come under serious criticism, and inspired significant policy initiatives and numerous debates. Nevertheless, it remains the most formidable contender against traditional state-centered thinking around national and international security. In this chapter, we will look at the emergence and evolution of the human security approach, its core components, and its relationship with other important notions such as human development and responsibility to protect.

This chapter examines the development of a right to privacy against the press in Article 8 ECHR and the legal principles that apply in such cases. It considers the obligations that Article 8 imposes in respect of the activities of private actors, the criteria for balancing competing rights, and the role of the margin of appreciation and the ECtHR in that process. The chapter then considers the impact of Articles 8 and 10 on domestic law and the development of the tort of misuse of private information. This offers important insight into the ways in which the Convention rights and the HRA have shaped the common law. Finally, the chapter concludes with observations on prospects for the future and proposals to limits privacy rights.

Peace Science research is interested in understanding the causal relationships between independent and dependent variables. Based on prior knowledge or existing theories, they develop hypotheses about the strength and direction of impact of independent variables on dependent variables, whether they be arms races and war, economic stability and civil war, or democracy and peace. Quantitative methods provide researchers with a way of confirming or disconfirming these hypotheses.

Article 10 ECHR protects freedom of expression, but this is not absolute, and States can prohibit hate speech. There is, however, no definition of ‘hate speech’ and while this reflects its context-specific nature, the latitude that this affords gives rise to concern. It is also difficult to know where lines should be drawn and what role human rights law should play. This chapter thus begins by considering free speech theory and why using law to tackle hate speech is contested. It then examines the ECHR framework where hate speech sits at the interface between Articles 8, 10, 14 and 17 ECHR. It observes that although the initial case law concerned the compatibility of domestic restrictions on hate speech, the Court has since held that States have positive obligations to protect those who are targeted by hate speech. This raises several challenges, not least that it becomes more pressing to know what constitutes ‘hate speech’ when States are obliged to address it. The latter part of the chapter examines domestic law where hate speech laws have come under immense scrutiny in recent years and where proposals have been made for reform.