The epistemic ground of situated comparability is therefore double. Some continuity is indispensable: shared variables, recurrent locations, traceable routes, stable identifiers or sufficiently persistent questions. Yet excessive standardisation destroys the very differences comparison is meant to illuminate. Espeland and Stevens expose the political work hidden inside common metrics; Leonelli shows that evidence changes meaning as it travels; Marcus and Pink demonstrate that movement across sites and embodied participation alter what the field itself is. Comparison becomes rigorous not when context disappears but when the transformation of context remains inspectable. A valid comparison preserves provenance alongside equivalence. Time intensifies this problem. A single observation can describe, but recurrence allows persistence, change, accumulation and adaptation to emerge. Fjellstad’s repeat photography shows that the initial act of recording already anticipates a future return. Sturm’s repeated awe walks reveal emotional effects that accumulate unevenly, while Cheng’s sequential routes demonstrate that one environmental episode modifies the experience of the next. Lorenzo’s work makes the same transition visible at a larger conceptual scale: from restorative urban settings to remembered environments and then to walking itineraries, with a future research horizon explicitly opened toward temporal and collective processes. Longitudinality is thus not simply more duration. It is the capacity to make separated moments answerable to one another. Spatial abstraction offers another route to comparison. Urban morphology and predictive pedestrian modelling create portable descriptions by converting complex environments into variables, types and forecastable relations. Their power lies in scale: a model can compare multiple cities or project movement into a future street network because it suppresses much of the local thickness that ethnography retains. This is neither a defect nor a virtue in itself. It is a specific evidential trade. Situated comparability requires the ability to move between high-resolution immersion and reduced formal description without confusing one for the other. The decisive question is always which transformations are legitimate for the claim being made. Socioplastics becomes operational at precisely this junction. Its field is not strengthened by choosing between immersion and abstraction, conversation and metric, photograph and model, archive and present encounter. It is strengthened by making the transitions among them explicit. A recurring photograph can become a spatial datum; a conversation can become a temporal trace; a repeated route can become a comparative unit; a model can become a test against observed behaviour; a dataset can be reused only if its lineage remains reconstructable. The archive is therefore not a terminal store but an infrastructure for producing future comparability: it holds enough continuity for later returns while preserving the differences that make those returns meaningful. Situated comparability adds a precise epistemic discipline to Socioplastics: compare without flattening, repeat without pretending identity, move evidence without severing provenance, and formalise only to the degree required by the claim. It converts longitudinal practice from accumulation into an architecture of revisitable relations. In this sense, the strongest field is neither the most standardised nor the most immersive, but the one capable of sustaining calibrated passages between scales, media, times and forms of evidence. Within Socioplastics, this constellation condenses as RelationalLongitudinality.
