That rebels face a collective action problem is one of the most widely shared assumptions in the literature on civil wars. The authors argue that the collective action paradigm can be both descriptively inaccurate and analytically misleading when it comes to civil wars. They question both pillars of the paradigm as applied to the study of civil wars, namely, the free-riding incentive generated by the public goods dimension of insurgency and the risks of individual participation in insurgent collective action. The authors argue, instead, that although insurgent collective action may entail the expectation of future collective benefits, public (rather than just private) costs tend to predominate in the short term. Moreover, the costs of nonparticipation and free riding may equal or even exceed those of participation. The authors support these claims by triangulating three types of evidence: historical evidence from counterinsurgency operations in several civil wars; data from the Vietnam War's Phoenix Program; and regional evidence from the Greek Civil War. They conclude by drawing implications for the study of civil wars.

The most commonly used statistical models of civil war onset fail to correctly predict most occurrences of this rare event in out-of-sample data. Statistical methods for the analysis of binary data, such as logistic regression, even in their rare event and regularized forms, perform poorly at prediction. We compare the performance of Random Forests with three versions of logistic regression (classic logistic regression, Firth rare events logistic regression, andL1-regularized logistic regression), and find that the algorithmic approach provides significantly more accurate predictions of civil war onset in out-of-sample data than any of the logistic regression models. The article discusses these results and the ways in which algorithmic statistical methods like Random Forests can be useful to more accurately predict rare events in conflict data.

Aerial bombardment has been an important component of counterinsurgency practice since shortly after it became a viable military technology in the early twentieth century. Due to the nature of insurgency, bombing frequently occurs in and around settled areas, and consequently it tends to generate many civilian casualties. However, the effectiveness of bombing civilian areas as a military tactic remains disputed. Using data disaggregated to the level of the smallest population unit and measured at multiple points in time, this article examines the effect of aerial bombardment on the pattern of local control in the Vietnam War. A variety of estimation methods, including instrumental variables and genetic matching, show that bombing civilians systematically shifted control in favor of the Viet Cong insurgents.

The authors analyze a unique data source to study the determinants of violence against civilians in a civil war context. During the Vietnam War, the United States Department of Defense pioneered the use of quantitative analysis for operational purposes. The centerpiece of that effort was the Hamlet Evaluation System (HES), a monthly and quarterly rating of 'the status of pacification at the hamlet and village level throughout the Republic of Vietnam'. Consistent with existing theoretical claims, the authors find that homicidal violence against civilians was a function of the level of territorial control exercised by the rival sides: Vietnamese insurgents relied on selective violence primarily where they enjoyed predominant, but not full, control; South Vietnamese government and US forces exercised indiscriminate violence primarily in the most rebel-dominated areas. Violence was less common in the most contested areas. The absence of spatial overlap between insurgent selective and incumbent indiscriminate violence, as well as the relative absence of violence from contested areas, demonstrates both the fundamental divergence between irregular and conventional war and the need for cautious use of violent events as indicators of conflict.

The conflict in Iraq has been portrayed as “ethnic” civil war, a radically different conflict from “ideological” wars such as Vietnam. We argue that such an assessment is misleading, as is its theoretical foundation, which we call the “ethnic war model.” Neither Iraq nor Vietnam conforms to the ethnic war model's predictions. The sectarian conflict between Shia and Sunni militias is not simply the outcome of sectarian cleavages in Iraqi society, but to an important extent, a legacy of U.S. occupation. On the other hand, although Vietnam was a society riven by ethnic cleavages, the Vietnam War also fails to conform to the ethnic war model. We show that there is no necessary overlap between ethnic conflict and ethnic war. Some ethnic conflicts evolve into ethnic wars, and others develop dynamics virtually indistinguishable from those of ideological civil wars. We suggest that the state's role is essential in transforming conflicts into either ethnic or irregular wars. We conclude with an analysis of the current situation and future prospects in Iraq.

Reinforcer pathology is derived from the integration of two measures: (a) self-control (i.e., delay discounting), and (b) reward valuation (i.e., behavioral economic demand). Narrative theory asserts that vividly imagining oneself in a hypothetical, yet realistic, scenario can acutely alter decision making, valuation of reinforcers such as food, and how much food is consumed. The present study measured changes in reinforcer pathology for highly palatable snacks following either a negative or neutral scenario in obese individuals. Participants (N ϭ 48), with a body mass index of 30 or greater, rated their liking of 7 calorie-dense snack items and completed discounting and purchase demand tasks for their top-rated snack. Participants then read a randomly assigned hypothetical scenario (i.e., a devastating hurricane [negative] or minor storm [neutral]), completed the tasks again, and were given ad libitum access to their top 3 ranked snack foods. Results indicated that delay discounting, demand for participants' top-rated snack food, and negative affect all increased in the hurricane group compared with the minor storm group. The hurricane group also consumed more calories, even when hunger was standardized with a preload meal bar. Consistent with reinforcer pathology, these results suggest that vivid consideration of a devastating scenario constricts the temporal window and increases demand for hedonic snack foods among obese individuals.

The smallest genomic region causing Prader-Willi Syndrome (PWS) deletes the non-coding RNA SNORD116 cluster; however, the function of SNORD116 remains a mystery. Previous work in the field revealed the tantalizing possibility that expression of NHLH2, a gene previously implicated in both obesity and hypogonadism, was downregulated in PWS patients and differentiated stem cells. In silico RNA: RNA modeling identified several potential interaction domains between SNORD116 and NHLH2 mRNA. One of these interaction domains was highly conserved in most vertebrate NHLH2 mRNAs examined. A construct containing the Nhlh2 mRNA, including its 3’-UTR, linked to a c-myc tag was transfected into a hypothalamic neuron cell line in the presence and absence of exogenously-expressed Snord116. Nhlh2 mRNA expression was upregulated in the presence of Snord116 dependent on the length and type of 3’UTR used on the construct. Furthermore, use of actinomycin D to stop new transcription in N29/2 cells demonstrated that the upregulation occurred through increased stability of the Nhlh2 mRNA in the 45 minutes immediately following transcription. In silico modeling also revealed that a single nucleotide variant (SNV) in the NHLH2 mRNA could reduce the predicted interaction strength of the NHLH2:SNORD116 diad. Indeed, use of an Nhlh2 mRNA construct containing this SNV significantly reduces the ability of Snord116 to increase Nhlh2 mRNA levels. For the first time, these data identify a motif and mechanism for SNORD116-mediated regulation of NHLH2, clarifying the mechanism by which deletion of the SNORD116 snoRNAs locus leads to PWS phenotypes.

Qualitative historical knowledge is essential for validating natural experiments. Specifically, the validity of a natural experiment depends on the historical processes of treatment assignment and administration, including broader macro-historical dynamics. But if validating a natural experiment requires trust in the ability of qualitative evidence to establish the causal processes through which the data were generated, there is no good reason for natural experiments to be considered epistemically superior to historical research. To the contrary, the epistemic status of natural experiments is on a par with that of the historical research on which their validation depends. They are two modes of social-scientific explanation, each with its own pros and cons; neither is privileged. We illustrate this argument by re-examining an important recent contribution to the literature on violent conflict: Ferwerda and Miller’s 2014 natural experiment estimating the causal effect of the German decision to devolve authority to the Vichy French government on violent resistance during World War II.