Taddei and Paolucci define social science infrastructure as a hybrid object: simultaneously technical system, organisational framework and social contract. This formulation displaces infrastructure from the background of research into the domain of active epistemic and political construction. Longitudinal data systems require continuous negotiation with privacy law, statistical institutions, changing ethical standards, funding regimes and communities whose trust sustains participation over time. Their distinctive methodological contribution is temporal: infrastructure is distinguished from the episodic research project by maintenance, stewardship and durability. The introduction also makes an explicitly political claim. European research infrastructures are mechanisms of interoperability, cohesion and shared capacity and, in a context of technological dependence, can become instruments of democratic sovereignty. The text bridges infrastructure studies, European research policy and social science methodology by making visible the care work and institutional imagination that allow knowledge systems to persist. Durability is therefore not passive storage but an organised capacity to remain legitimate, adaptable and publicly accountable through change.
