International audience The chapter builds on Dobrovie-Sorin and Mari’s (2007a,b) claim that the unacceptability of the generic readings of French plural indefinites headed by des ‘deplur’ is due to a constraint that prevents variables that range over elements ordered by the part-whole relation from being bound by a quantifier. This account is shown to extend to mass indefinites, bare plurals and German keine-indefinites. A careful characterization of plural symmetric nouns (neighbours, parallels) explains why such predicates allow for generic readings: the maximal groups that satisfy the relation denoted by the noun (neighbourhood, parallelhood) are not ordered by the part-whole relation. The chapter has two important theoretical consequences: (i) it restricts the possible analyses of generic bare plurals: they cannot be analyzed as indefinite-like expressions, but only as names of kinds; (ii) quantifiers over the mass domain cannot be assumed to denote relations between sets of portions of matter but rather relations between objects (maximal sums).