1In Knowledge, Evidence, and Policymaking: Behavioural Sciences in Australia, Einfeld offers a compelling contribution to contemporary debates about how knowledge informs public policy. While the book centres on behavioural insights and behavioural science using an Australian case study, its relevance extends far beyond these domains. Scholars of public policy, evidence use, epistemology, and governance will all find significant value in this text. Einfeld’s central argument that “how we use knowledge matters” and that policy-relevant knowledge is never singular or stable but instead “tangled”, positions the book squarely within current scholarly debates about expertise, evidence, and the politics of knowledge.

2This book’s most significant contribution lies in foregrounding the multiplicity of knowledges that shape behavioural insights in practice. As Einfeld states in the introduction, how policy actors use knowledge matters, and this knowledge cannot be reduced simply to the field of evidence. Rather knowledge is complex, or tangled, to use Einfeld’s language, and can include diverse forms of knowledges such as technological, local, craft, and normative knowledge. This epistemic framing opens up new ways of understanding how behavioural insights are mobilised, translated, resisted, or legitimised within bureaucratic contexts. Given the continuing global expansion of behavioural science approaches, this intervention is timely and important. It also speaks to broader debates in interpretive policy studies about the social production of knowledge, the politics of legitimacy, and the boundaries of expertise.

3The early chapters offer an accessible overview of the history of nudge, behavioural insights, and behavioural science in policy. Einfeld traces the rise of these approaches, beginning with the UK’s Behavioural Insights Team, before mapping its global diffusion. Importantly, she also outlines the critiques that have accompanied this rise - concerns about paternalism, transparency, democratic legitimacy, and the gap between behavioural insights’ rhetorical claims and their practical implementation. While these discussions are necessarily selective, Einfeld wisely avoids becoming bogged down in well-worn debates. Instead, she quickly moves to her central analytical interest: how do policy actors navigate the different forms of knowledge that shape behavioural insights in policy?

4Drawing on interviews with practitioners, consultants, and academics in Australia, Einfeld uncovers contradictions, frictions, and tensions. Rather than smoothing over these inconsistencies, she uses them as the basis for her analysis, showing how actors make sense of behavioural insights within the constraints, expectations, and politics of the public sector. Her interpretive lens proves well suited to illuminating these dynamics.

5Much of the book’s richness comes from its exploration of the different forms of knowledge that policy actors draw upon and this is explored in depth in the Chapters 1 through 4. Einfeld shows how technical knowledge, especially quantitative forms, are repeatedly invoked as the hallmarks of objectivity and legitimacy. This privileging of technical knowledge confers authority on behavioural insights but also constrains the kinds of problems and solutions that are deemed valid. This is counterbalanced by local knowledge – gained from service users, frontline workers, and community contexts – and is treated as empirically useful, but often deprioritised. Craft knowledge receives similarly thoughtful attention. Einfeld convincingly shows how persuasion, relational work, and strategic alignment shape the uptake and adaptation of behavioural insights. Policy actors draw on their craft knowledge to connect behavioural techniques to institutional values such as efficiency, revenue, and impact. As she notes, behavioural insights becomes “a making of evidence,” embedded in organisational cultures rather than merely imported from scientific research. Normative knowledge refers to knowing what is ‘right’. This is, of course, inherently and importantly driven by context and is therefore linked to local knowledge. In reference to behavioural insights, it is also interesting to note the belief that using behavioural approaches is an inherently better way of making policy. This links normative and technical knowledge in interesting and complex ways. Chapter 5 provides a particularly insightful discussion on the politics of evidence, foregrounding the argument that “evidence is knowledge labelled in a political act.” This will resonate strongly with scholars of evidence-based policymaking. It tells a story of how behavioural insights has used claims of evidence-based policy making to protect itself from some of its biggest areas of critique – namely ethics and top-down policy making. It is these challenges Einfeld turns to next.

6Chapter 6 speaks to the ethical concerns of both nudge and RCTs, such as autonomy, agency, transparency, and preference construction. Einfeld goes further than much existing literature by examining policy actors’ own ethical reasoning, especially the belief, widely held among practitioners, that not nudging could be unethical if nudges help people make “better” decisions. Einfeld rightly highlights the problem here: preferences are often unknown, especially across diverse populations, making it difficult to design ethically robust interventions. This is one of the book’s strongest sections.

7Chapter 7 investigates the tensions between behavioural insights, collaboration, and co-design. Can behavioural insights be driven from the bottom-up? Can it be truly collaborative? Einfeld argues that behavioural insights, in practice, privileges technical knowledge which puts it in direct conflict with collaboration and co-design. Co-design elevates local and experiential knowledge and collaboration requires a willingness to accommodate different forms of knowledge. Whether this tension is inherent to behavioural insights or a byproduct of its institutionalisation is open to debate; nevertheless, Einfeld’s analysis is convincing in demonstrating how these tensions manifest in real policy settings.

8The concluding chapter situates behavioural insights within debates on decolonisation and global knowledge hierarchies. Einfeld asks whether behavioural approaches developed in WEIRD (Western, Educated, Industrialised, Rich, Democratic) contexts can be responsibly exported to policy systems that value different forms of knowledge. These questions are vital, and although the chapter is more exploratory than empirical, it points toward a promising research agenda.

9The book will be of particular interest to scholars and students in public policy, public administration, political sociology, STS (science and technology studies), and behavioural science. Practitioners in government, especially those working in behavioural insights teams, evaluation, or evidence units, will also recognise many of the dilemmas and insights the book surfaces. Its interpretive approach may be especially appealing to those who are less convinced by the rapid institutionalisation of behavioural science in policy systems.

10This book is a significant contribution to contemporary debates about behavioural science, knowledge in policy, and the politics of expertise. Einfeld provides a nuanced analysis of how behavioural insights is practised, revealing the multiple and sometimes conflicting forms of knowledge that shape its translation into policy. The book raises important questions about legitimacy, ethics, and decolonisation - questions that will no doubt shape future scholarship. I count myself among those eager to see where Einfeld takes this research next.