Modality and facivity : One perspective on the meaning of the English modal auxiliaries

This study concentrates on modality as expressed by the set
of modal auxiliaries and seeks to establish that these
verbs share semantic as well as syntactic properties by
identifying a single core meaning which they share. The
relationship between modality and factivity is examined
with the aim of gaining an insight into the former, more
complex concept. When viewed from this perspective, the
defining characteristic of all the modal auxiliary verbs in
almost all of their uses is found to be nonfactivity. The
meanings expressed by this set of verbs are classified
according to a framework derived from modal logic
consisting of three basic types of modality each of which
relates to a different set of laws or principles; the
relative factivity associated with the modal auxiliaries is
seen to vary with the nature of modality as defined and
classified by this framework. Within each of the three
types of modality, a semantic scale is identified and
modality is described as a gradable concept for which
scalar analysis is appropriate, both within and beyond
these three scales. Relative factivity is also shown to
vary according to the degree of modality expressed by each
of the modal verbs. The nature and degree of modality
expressed interact with features of the linguistic (and
pragmatic) context to determine the particular factive or a
contrafactive interpretation conveyed by a given modal
auxiliary token. The influence of certain combinations of
contextual features is sufficiently strong to force a
factive or contrafactive reading of a modal token, although
in general the role of such features is merely to
strengthen or weaken the relative factivity associated with
the modal verb. Epistemic modality is seen to be most
directly related to nonfactivity and therefore to be the
most central modal meaning. The modal auxiliaries are
found to be semantically less modal when they occur in
contexts of determinate factual status. Least modal are
those members of this set of auxiliary verbs which in
certain uses have determinate factual status even without
the presence of any of the significant contextual
features.