The increasing fragmentation of global science limits the diffusion of ideas
Global science is often portrayed as a unified system of shared knowledge and open exchange. Yet this vision contrasts with emerging evidence that scientific recognition is uneven and increasingly fragmented along regional and cultural lines. Traditional models emphasize Western dominance in knowledge production but overlook regional dynamics, reinforcing a core-periphery narrative that sustains disparities and marginalizes less prominent countries. In this study, we introduce a rank-based signed measure of national citation preferences, enabling the construction of a global recognition network that distinguishes over- and under-recognition between countries. Using a multinomial logistic link prediction model, we assess how economic, cultural, and scientific variables shape the presence and direction of national citation preferences. We uncover a global structure composed of multiple scientific communities, characterized by strong internal citation preferences and negative preferences between them-revealing growing fragmentation in the international scientific system. A separate weighted logistic regression framework suggests that this network significantly influences the international diffusion of scientific ideas, even after controlling for common covariates. Together, these findings highlight the structural barriers to equitable recognition and underscore the importance of scientific community membership in shaping influence, offering valuable insights for policymakers aiming to foster inclusive and impactful global science.