The quote above—the very last sentence of this book—well represents the main message of the book. That is if we want to fully understand the world of refugees both for policy making and knowledge production, a systems approach is needed. Unlike the siloed approach, the systems approach analyzes the entire system in a holistic manner considering interactions and feedback within and across individuals, institutions, and nation states. It also cuts across space and time. Hence, it is not unrealistic that country or area of destination receiving asylum seekers today may experience refugee exodus in the future given sociopolitical uncertainties and instability.

In contrast, the common practice both in scientific work and the policy arena is a siloed approach where (1) historical contexts are not considered, (2) the causes of displacement are explained in a generic manner, (3) the use of the term “refugee” is bound to a legal definition, (4) there is a narrow focus on those who have moved across the border, (5) there is an emphasis on “durable solutions” (i.e., local integration, resettlement, and voluntary repatriation), and (6) displacement is treated as a single isolated stage (e.g., asylum seeking or resettlement). In doing so, a full account of the causes and consequences of refugeehood and refugeedom is not captured and this can affect policy design. For instance, a focus on mobility means those who are immobile—possibly because they got killed or do not have the means to move—are not included in the study. However, these population subgroups are likely to be the most vulnerable in a society producing refugees, and their exclusion means they are left out from policy interventions.

Through the lens of historical sociology, the book thus proposes “categories of analysis” based on a sociological definition of forced migration as opposed to “categories of practice.” The latter concerns “the categorising institutions [rather] than the characteristics of categorised people” (p. 23). The sociological definition, on the other hand, attempts to represent a reality whereby individuals or groups in refugeehood are considered as de facto refugees even though they are not institutionally nor legally recognized as refugees. In Chapter 2, the book offers a comprehensive discussion around the question of “who is a refugee?” such as whether refugees identify themselves with a refugee label and whether refugees are migrants.

The systems approach presented in the book shows that refugeehood—“the experience of becoming and being a refugee” (p. 6)—encompasses many other actors including immobile individuals, displaced persons, deportees, resettled refugees, returnees, and returnees. Likewise, individuals also often move between categories and capturing such dynamics is challenging. Arguing that “movement must be explained, not assumed” (p. 225), the book offers insights into why some people end up fleeing their home and some do not through a systems approach which allows for the possibility to consider various movement outcomes along the continua of coercion (Figure 2.4 of the book).

By focusing on refugees’ quantification, estimation, and prediction/forecasting, the demographic approach by design adopts a definition of a refugee as a single stage, because only then can refugees be counted using a clear-cut definition. Nevertheless, this approach does have practical advantages regarding quantification of refugees and empirical research about refugees. In this vain, data from the United Nations High Commissioner for Refugees (UNHCR) based on the universal definition of a refugee under the 1951 Geneva Convention, for instance, come handy because they allow researchers to investigate questions regarding the drivers and consequences of refugees and asylum seekers (see, e.g., Abel et al. 2019). Furthermore, alternative data sources (e.g., mobile and social media data) and advanced methods can potentially contribute to the improvement of refugee estimates (Muttarak 2021). Perhaps this is a new avenue enabling researchers to go beyond the use of a legal definition and explore how those living in refugeehood (e.g., immobile individuals, resettled refugees, returnees, and deportees) as presented in the systems approach can be accounted for.

To better understand refugees’ decision-making processes (i.e. “should I stay or go?” p. 74), the book proposes the “new economics of displacement” which is developed from the new economics of labor migration theory. Essentially, this theory analyzes migration decision-making at the household level, which reflects very well the reality of forced migration. For example, an entire family does not always flee the threat of violence or persecution at the same time, or some family members may not even move at all. The focus only on an individual's movement in the siloed approach would miss out the processes of how households or communities manage different kinds of risks and opportunities as well as capturing different types of mobility and immobility. The book illustrates such complexity by presenting a case study of the Asfour family affected by the Syrian civil war. The role of family and transnational ties in shaping the lives of refugees are generally difficult to capture in demographic analysis, and the book intelligently fills this missing link.

The book's content is organized into nine chapters with interconnecting themes. When relevant, the authors refer to the content of previous or upcoming chapters, allowing the reader to pick a specific section they are particularly interested in. This makes it possible to read the book in a nonchronological manner. However, this occasionally leads to repetition. For example, there are some substantial overlaps in Chapter 6: Hosting the Many Global Souths and Chapter 7: Powerful Hosts. The two chapters focus on host countries splitting between host countries in the global south in Chapter 6 and those in the global north in Chapter 7. Combining the two chapters together would help make the content more concise. Furthermore, some descriptions or arguments can be made clearer through visualization aids. For instance, a chord diagram can be used to represent the fact that the majority of refugees are hosted in the Global South, where are refugees from, and where do they go—or even the periodic change in refugee patterns (Abel and Sander 2014; Qi et al. 2017). This type of visualization can help illustrate the interconnectedness and interactions between states in different world regions.

In short, this book has demonstrated the value of using a systems approach to understand the refugee system. While it is challenging to empirically measure and capture all interactions between refugee drivers, actors, states, policies, and institutions involved, the book has shown that demographic analysis can benefit from using a holistic approach in the production of knowledge about refugees.

上面的引言——本书的最后一句话——很好地表达了本书的主要信息。也就是说，如果我们想充分了解难民的世界，无论是政策制定还是知识生产，都需要一种系统方法。与孤立方法不同，系统方法以整体方式分析整个系统，考虑个人、机构和民族国家内部和之间的相互作用和反馈。它还跨越了空间和时间。因此，鉴于社会政治的不确定性和不稳定性，今天接收寻求庇护者的目的地国家或地区未来可能会出现难民外流，这并非不现实。

相比之下，科学工作和政策领域的常见做法是一种孤立的方法，其中（1）不考虑历史背景，（2）以通用方式解释流离失所的原因，（3）使用术语“难民”受到法律定义的约束，(4) 狭隘地关注那些跨越边境的人，(5) 强调“持久解决方案”（即就地融合、重新安置和自愿遣返） )，(6) 流离失所被视为一个单独的阶段（例如，寻求庇护或重新安置）。这样做时，无法充分考虑难民和避难的原因和后果，这可能会影响政策设计。例如，对移动性的关注意味着那些无法移动的人（可能是因为他们被杀或没有移动能力）不包括在研究中。然而，这些人口亚群体可能是产生难民的社会中最脆弱的群体，他们被排除在外意味着他们被排除在政策干预之外。

因此，通过历史社会学的视角，本书提出了基于强迫移民的社会学定义的“分析类别”，而不是“实践类别”。后者涉及“分类机构[而不是]被分类的人的特征”（第23页）。另一方面，社会学定义试图代表这样一个现实：难民中的个人或群体被视为事实上的难民，尽管他们在制度上或法律上并未被承认为难民。在第二章中，本书围绕“谁是难民？”这个问题进行了全面的讨论。例如难民是否将自己贴上难民标签以及难民是否是移民。

书中提出的系统方法表明，难民身份—— “成为难民和成为难民的经历”（第 6 页）——涵盖许多其他参与者，包括不动的个人、流离失所者、被驱逐者、重新安置的难民、返回者和返回者。同样，个人也经常在类别之间移动，捕捉这种动态是具有挑战性的。该书认为“运动必须被解释，而不是假设”（第 225 页），通过系统方法，可以考虑沿途的各种运动结果，深入了解为什么有些人最终逃离家园，而有些人却没有逃离家园。强制的连续性（本书图2.4）。

通过关注难民的量化、估计和预测，人口统计方法在设计上采用了单一阶段的难民定义，因为只有这样才能使用明确的定义来统计难民。尽管如此，这种方法在难民量化和难民实证研究方面确实具有实际优势。然而，联合国难民事务高级专员办事处 (UNHCR) 根据 1951 年《日内瓦公约》对难民的普遍定义提供的数据却派上用场，因为它们使研究人员能够调查有关难民的驱动因素和后果的问题，寻求庇护者（例如，参见 Abel 等人，2019）。此外，替代数据源（例如移动和社交媒体数据）和先进方法可能有助于改善难民估计（Muttarak 2021）。也许这是一个新的途径，使研究人员能够超越法律定义的使用，并探索如何解释系统方法中提出的那些生活在难民中的人（例如，无法流动的个人、重新安置的难民、返回者和被驱逐者）。

更好地了解难民的决策过程（即“我应该留下还是走？”p。74）书中提出了由新劳动力迁移经济学理论发展而来的“新移民经济学”。该理论本质上是分析家庭层面的移民决策，很好地反映了强迫移民的现实。例如，整个家庭并不总是同时逃离暴力或迫害的威胁，或者一些家庭成员甚至可能根本不搬家。在孤立的方法中只关注个人的运动会错过家庭或社区如何管理不同类型的风险和机会以及捕获不同类型的流动性和不流动性的过程。这本书通过对受叙利亚内战影响的阿斯福家族进行案例研究来说明这种复杂性。

本书的内容分为九章，主题相互关联。当相关时，作者会参考之前或即将到来的章节的内容，允许读者选择他们特别感兴趣的特定部分。这使得以非时间顺序的方式阅读这本书成为可能。然而，这有时会导致重复。例如，第 6 章：接待全球许多南方国家和第 7 章：强大的东道国之间存在一些实质性重叠。这两章的重点是第六章中南半球东道国和第七章中北半球东道国的划分。将两章结合在一起将有助于使内容更加简洁。此外，一些描述或论点可以通过可视化辅助工具变得更加清晰。例如，2014年；齐等人。2017）。这种类型的可视化可以帮助说明世界不同地区国家之间的相互联系和相互作用。

简而言之，本书展示了使用系统方法来理解难民系统的价值。虽然凭经验衡量和捕捉难民驱动者、行动者、国家、政策和相关机构之间的所有相互作用具有挑战性，但这本书表明，人口分析可以受益于使用整体方法来生产有关难民的知识。