A05 investigates situationally and functionally driven intra-individual variation involving alternatives that differ in their core logical or truth-conditional content. The project pursues two complementary perspectives, one bottom-up, building multi-factorial models of specific domains of variation, and one top-down, looking for generalizations across domains. For the former, the initial empirical domain of investigation is numerical (im)precision, for the latter, German indefinite expressions. Then general properties of meaning-driven variation will be identified, exploring two initial hypotheses: (i) A basic dichotomy exists between meaning-driven and form-driven variation, namely, when differences in logical meaning among alternatives exist, this must drive the variation. (ii) The semantic relationship between two register alternatives is constrained to subset relations.