Should Latin America be considered just another region where the east–west opposition resulting from the Cold War had to be extended and reproduced? Is there no other way to capture both the national and international political dynamics of this region other than in terms of uncritical adherence or unquestioned alignment to either of the hegemonic systems opposing each other from 1947, namely the USSR and the USA? Or might it prove possible to track down, during this tense period, alternative projects striving for a collective solution and attempting to temper the ideological disputes while involving additional issues specific to the Latin American reality?

To answer such and other questions relating to the political dynamics and processes initiated by the various left-wing forces in Latin America, key elements are provided by the findings of Fernando Pedrosa following five years of research aimed at exhaustively and rigorously analysing the influence of social democracy between 1978 and 1990. His theoretical-empirical results in the field of research that links history and political science are the best documented of recent decades, and, in this particular case, they also combine analytical categories specific to the sphere of Latin American studies with others specific to contemporary political processes – both are Pedrosa's specialist areas of expertise.

The author's assiduous work in exploring whether, in the context of the Cold War, a moderate proposal transcending the bipolar logics could emerge allows one to envision politics and the actions of political players in terms of historical time, in terms, for example, of processes. To achieve this, a methodology was required that combined a historical reconstruction of the international, regional, and national contexts in which the different social democratic organizations or groups and their representatives were moving, with an analysis of their respective ideological traditions, the evolution of their political programmes, and the development of their organizational strategies. Though the historical viewpoint allows one to assess events with the benefit of hindsight, by adding further evaluative elements to the analysis of social democracy – and of the Socialist International (SI) as an organic driving force behind its ideals – it was also necessary to rely on new sources of information to get a better understanding of how their organizational life developed.

Access to both the SI historical archives kept at the International Institute of Social History (IISH), including letters between leaders of political parties, confidential documents, communiqués, government reports, and personal notes, and to the archives of the SI Latin American Secretariat enhanced the options available to Pedrosa regarding the quality of his investigative work. Such a qualitative leap forward was possible due also to the complementary use of interviews with key players involved in the SI or with their close associates, which yielded highly valuable data. Such sources enabled the author to back up observations on the political activity of social democracy in Latin America with documentary evidence. These activities were neither improvised nor of little relevance. Nor should their study be limited to a formal approach that analyses only official sources such as by-laws, Congress statements, or resolutions. On the contrary, they highlight the fact that activities were always well targeted and focused.

All this information, documented and analysed in detail and in a language accessible to both the general reader and those with an academic background, can be systematized in such a way that the core thesis of Pedrosa's book – that, as an international and transnational organization, the SI deployed strategies, alliances, pacts, and dynamics that contributed to weakening authoritarian regimes and to creating an opportunity for the process of democratization in Latin America – is compelling and, up to now, irrefutable given the documentary evidence. Pedrosa's multidisciplinary approach – which resorts simultaneously to the historical and political analysis of events revealing the organizational life and the political project of social democracy, both as an ideology and practice – is reflected in the very structure of his book. Divided into two sections, the first is dedicated to the SI, its creation, and the Marxist tradition to which it belongs. The second considers the role this transnational party organization played within Latin American politics between 1976 and 1990. The combination of both approaches results in a work aptly defined by Pedrosa as a political history of the SI and social democracy and as a history of international politics.

In the first part of La otra izquierda the author provides a complete overview of the emerging SI, describing its nature as a second-level organization bringing together political parties with variegated interests and forms of representation, and dating its foundational process to the Frankfurt Congress in 1951 at which a declaration of principles was presented that did not, however, go beyond specifically European concerns about regional security and European alarm in the face of Soviet expansionism. The evolution of SI dynamics in the light of political events is also commented on by means of transversal reflections on the historical division of the global worker union, on socialism as opposed to communism, and by highlighting the fact that social democracy drew on the thoughts of Eduard Bernstein. These stressed the notion of movement, daily political action, and of maintaining the state as a power structure that should be occupied and taken advantage of to move closer to democratic consolidation.

Thus, Pedrosa analyses the reorganization of the SI and its basic programmes and strategies up to the point when it became a visible collective project with worldwide recognition, without, however, failing to examine specifically the origins of social democratic thinking, of its internationalist aspirations, and of the main concepts at the core of its discourses. Outstanding among them, we find the notion of democracy, with the formal elements characterizing it, such as electoral mechanisms, pluralism, and the central role of the parties as political players, as well as other notions complementing it and relating socialism to freedom, justice, and solidarity.

The second section of the book addresses the learning process of the SI both at the organizational level and regarding the articulation of specifically political strategies, the focus now being placed on the Latin American context and on action taken so as to influence it and be influenced by it. With such regional democratization, it is not just the prevailing geopolitical logics that are altered; certain subjects and issues initially concerning these specific countries could also acquire a place on the international agenda. Since then, the north–south confrontation, economic inequalities, gender inequalities, development, and environmental protection have become subjects of international concern.

Although the turning point in this change was marked by the Caracas Congress and the nomination of Willy Brandt as President of the SI in 1976, Pedrosa recalls the contributions made since 1955 by the SI Latin American Secretariat under the leadership of Humberto Maiztegui who, disseminating information about the different Latin American realities and putting the social democrat leaders of Latin America in contact with one another and with their European counterparts, helped show that the best way to strengthen the SI and to have effective power was to encourage the constitution of a network of formal and informal relationships at all organizational levels.

Finally, another contribution of great importance in Pedrosa's book is its reference to the strategies deployed by the SI in Latin America, extending from the direct involvement of the SI in sending open support missions to its affiliated members in the region to the opening of the institutional flowchart in order to involve Latin American parties and political leaders in the decision-making process and to use informal relationships to meet the challenges arising in changing contexts. Thus, the SI became a flexible and influential space, still fundamentally political, with the consequence that SI internal alliance processes based on personal affinities ended up combined with consensus and conciliatory resolutions in the event of disputes, conflict, and internal divergence.

In short, La otra izquierda opens a new direction often ignored when social research projects are undertaken: its approach suggests that historical and political analyses cannot be limited to the specific study of events and ideas. On the contrary, for such analyses to be balanced and comprehensive, account must be taken of the political subjectivities of the players involved in a transformative project and who, for its positioning, developed intellectual, organizational, and strategic creativity.