Meaning change in grammaticalization has been variously described in terms of decreasing semantic weight and increasing generality, abstraction, (inter)subjectivity or discourse orientation. The author shows that all these trends are subsumed by the notion of scope increase along a precise hierarchy of semantic and pragmatic layers of grammatical organization such as endorsed by Functional Discourse Grammar. The scope-increase hypothesis is immune from the exceptions and veritable counterexamples to all the aforementioned generalizations and has the decisive advantage of being more objectively measurable, given its direct bearing on actual linguistic structure. The extremely rare exceptions to this generalization are also addressed and found to always result from a type of change independent from grammaticalization – the merger of two separate speech acts.
