It is obvious that the main function of language is to serve as the instrument for the
transmission of information. In everyday communication, speakers do not simply describe some
event, process or state of affairs. Moreover, “the transmission of descriptive information is
usually not an end in itself” (Lyons, 1977). Speakers, by means of language, also wish to
express their emotions and attitudes, or to influence in some way the addressee’s beliefs and
behaviours. They often qualify their statements with respect to believability, reliability and
general compatibility with accepted fact, for example It must be raining; or else, intervene in
the speech event by laying obligation or giving permission: We must copy this out again; You’d
better come, too. This area of semantics that concerns those expressive and social information
of statements is modality. Since the semantic field of modality has, for most linguists, covered a
wide range of attitudinal notions of speech event, a number of types of language forms can
represent its concepts, among which the use of moods, modal verbs, performative verbs as well
as particles are very common in English and Vietnamese .
Though many pages and chapters, books have been written about the English modal
system, it still remains a complicated and troublesome area of language for linguists and
learners of English. The problem can be traced to the polysemy or ambiguity of modal
meanings. Semantically, a modal can have both deontic and epistemic meaning. In the
sociophysical (deontic) world, the must in John must go to all the department parties is taken
as indicating an obligation imposed upon the subject of the sentence by the speaker ( or by
some other agents). In the epistemic world, the must in the same sentence could be read as a
logical necessity according to the reasoning I must conclude that it is John’s habit to go to all
department parties (because I see his name on the sign-up sheet every time, and he’s always
out on those nights). In addition, there is considerable overlap between modals. It is hard to
discern any semantic difference among them since modals are almost substitutable in almost
contexts, such as should and ought to in I should/ ought to finish this essays tonight.
Pragmatically, we can talk about modal meanings in terms of such logical notions as
permission, obligation and prohibition performed by speech acts of directives and commissives,
but this done, we will have to consider ways in which these notions become remoulded by the
psychological pressures of everyday communication between human beings: factors such as the
effect of social distance, the power relationship between interlocutors, politeness, directness,
indirectness , mitigating devices and hedges. The appropriate use of the linguistic means to the
context is the matter of culture- specifics. A good knowledge of such factors plays an important
role in sustaining communication and good relationship between interlocutors.
In foreign language classes, focus is given on the teaching and learning of the linguistic
forms and functions. The pragmatic use of them in communication has completely been ignored
or not fully been introduced and practised. Moreover, the socio-cultural factors and routines of
the community using the language have not been mentioned. As a result, there is a gap
between classroom interactions and the authentic use of language in communication and thus
learners with good knowledge of a language may fail in his real communication

The learning of meaning of modal verbs, performative verbs and particles and how to
use them correctly has not been, then, an easy task for learners of English. Learners are often
confused in choosing the appropriate lexical devices to express certain notion of modality.
When I say, “John may go home now” to give John permission to leave, or when I advise,
“Elena should go home. She looks tired.” I am using deontic modality.
These descriptions raise several considerations. One of them is that I used the same
modal may in John may go home now to give John permission to leave (deontic) and to tell my
listener that I am not certain if John is leaving (epistemic), which may cause ambiguity. This
ambiguity is found throughout the modal system and is one of the reasons that classroom
activities and exercises focusing on modality can be so difficult to develop.
This problem is especially more embarrassing when they encounter different modals
conveying the same meaning. Also, they can produce grammatically correct utterances, but do
not understand properly the social and cultural information each modal meaning conveys.
Furthermore, due to the structuralist approach to grammar teaching, learners can memorize
modal words with their accompanying meanings, but do not know how to use them to improve
their communicative competence, say, to mitigate directness, to express politeness, to make
assertions in social interaction. Besides the modals, there are other means expressing deontic
modality: the notions of obligation, prohibition, permission, performed by speech acts of
directives, commissives such as performative verbs, particles and the imperative mood.
Although Palmer’s notional categories make sense, I found that it was difficult to
process the grammatical patterns in the language data used to illustrate the categories. Part of
my difficulty may be attributed to the fact that I believe modality needs to be studied in the
context of use, i.e., natural texts, not isolated sentences; and also, I believe that a thorough
study of all grammatical expressions of modality and mood must be done within a single
language before the results are compared and contrasted cross-linguistically. Such linguistic and
methodological viewpoints have revealed that a fully complete study on approaches to
syntactic, semantic and pragmatic analysis of modal meanings is essential, especially for
learners of English as a foreign language.