54 Chapter 3 Verbs, tense, aspect, and mood
Modality can be expressed by a great variety of formal means. The possibility
meaning of [5lic], for example, could also be expressed by means of an adverb
(Perhaps she saw him), an adjective (It's possible that she saw him), a noun (There 's
a possibility that she saw him), and so on. But for English at least the term 'mood'
is restricted to grammatical systems associated with the verb.
In §8.1 we look at the kinds of meaning expressed by the modal auxiliaries. Then
in §8.2 we take up the issue of the relation between modality and future time in the
context of an examination of the auxiliary will. In §8.3 we look at the preterite forms
of the modals. The final section, §8.4, deals with the use of were in constructions
like I wish she were here - a relic of an earlier system of mood marked by inflection,
rather than by auxiliaries.
8.1 Uses of the modal auxiliaries
There are three main families of meanings that the modal auxiliaries
express: epistemic, deontic and dynamic. The first two, illustrated in [51 i-ii]
respectively, are the most central ones, and we will take these two together in order
to bring out the important contrast between them. We will then conclude the section
with a discussion of dynamic modality.
The epistemic vs deontic contrast
Epistemic modality expresses meanings relating primarily to what is necessary or
possible given what we know (or believe): the term derives from the Greek word for
"knowledge". Deontic modality expresses meanings relating primarily to what's
required or permitted: this term derives from the Greek word for "obligation". The
two kinds of meaning are illustrated in the following pairs:
[52] EPISTEMIC DEONTIC
a. He must have overslept. b. He must apologise.
11 a. She may be ill. b. She may take as many as she needs.
111 a. The storm should be over soon. b. We should call the police.In the [a] examples the modals are interpreted epistemically: the varying degrees
of non-factuality that they convey reflect limitations on the speaker's knowledge.
In [ia], I may not know that he overslept, but I'm inferring that he did. In [ib], I
don't know that she's ill, but I also don't know that she isn't, and am counte
nancing it as a possibility. In [ic], I don't know how long the storm will last, but
the probability or expectation is that it will be over soon.
The [b] examples are interpreted deontically: the meanings have to do with obli
gation or permission of various kinds. More specifically, the operative notion in
[ib] is obligation, in [iib] permission, and in [iiib] a milder kind of obligation
where it is a matter of what is the right thing to do. These notions all have to do
with authority and judgement rather than knowledge and belief. Very often