Critical perspectives on bottom-up urban regeneration. practices, rhetorics and effects of change for an alternative city

This special issue examines bottom-up urban regeneration (RUDB) as a de facto paradigm requiring critical scrutiny. The curators situate RUDB within converging contemporary trends: horizontalized governance arrangements, renewed societal interest in territory as both civic value and economic asset, and the pragmatic turn in collective mobilization blending advocacy with direct production of public goods. The article problematizes the four terms composing RUDB: "regeneration" lacks analytical precision regarding actual impacts; "urban" encompasses heterogeneous contexts without clear definitional boundaries; "bottom" remains unproblematized despite encompassing diverse actors with varying power and resources; and "from" suggests a unidirectional flow toward institutions that oversimplifies complex multi-scalar networks. Three transversal themes emerge from the collected contributions: the problematic relationship between "high" and "low" in generating institutional learning; the increasingly blurred professional profiles of RUDB actors; and universities' evolving role in engaged research and territorial collaboration. The article calls for transdisciplinary, translocal reflection moving beyond case-study accumulation to interrogate how these initiatives alter citizens' interactions with the public sphere, establishing a research agenda for more rigorous conceptualization of this field of urban practice and theory.