All of linguistic change is gradual (and maybe continuous) in the sense that it is not perpetrated as an instantaneous revolution in the whole speech community, but spreads through it gradually over space and time. This aspect of linguistic change does not concern us here. In the present context, the notions of gradualness and continuity concern the linguistic system.

The notion of continuity plays an important role in theories of linguistic change which claim that it is subconscious, which is, of course, more plausible if change is continuous because then it may be imperceptible for speakers.

The notion of graduality plays an important role in theories of grammaticalization since they do not assume a sharp and categorical distinction between lexicon and grammar. Here are two examples of well-estblished grammaticalization paths which illustrate the definition of ‘gradual difference between stages’ provided in the preceding section:

relational noun > postposition > case suffix

pronoun > pronominal clitic > bound pronominal index

In both of these grammaticalization paths, the difference between the first and the second stage is of the same kind as the difference between the second and the third stage. The same goes for all grammaticalization paths.

For the comparison of some processes of linguistic change to be executed in neighboring sections of this website, we may keep in mind that

• not all linguistic change is gradual; for instance, analogical change is not gradual;
• not all linguistic change – and in particular not all sound change – is continuous; for instance, trivially metathesis is not continuous;
• grammaticalization is gradual;
• whether or not or in which sense grammaticalization is a continuous process is an empirical issue and in no way part of the concept itself.

Processes of grammaticalization may be complex, both in terms of sequential composition of a process in time and in terms of the synchronic combination of phenomena. It is quite possible that some ingredient changes are continuous, others are just gradual. Suppose, for instance, that the change from a postposition to a case suffix were toppling rather than gliding. It would no less be a process of grammaticalization.