Palmer (1979, 1990）classifies MVs into three types, namely, epistemic, deontic and dynamic modality.Each type subsumes possibility and necessity.What is worth noting in Palmer’s works is the discussion of the functions of MVs in conditionals and politeness strategy.Palmer (1979/1990: 71）also points out that some low-valued MVs like can are often used to convey a command of a brusque or somewhat impolite kind.This study underlies the assumption that the values of MVs do not keep constant.Instead, they vary through different linguistic forms (e.g.declarative, interrogative or imperative）depending on the contexts of communication.
Quirk et al.(1985: 221）study the communicative functions of MVs based on a large corpus.These scholars treat MVs in pairs and as a matter of being situated on a continuum, diagramed as follows in Figure 2.7.
From Figure 2.7, it can be found that the functions of MVs are not always constant.Instead, one modal sense could be converted to another one based on communicative settings.For instance, must indicates intrinsic, committed obligation, whereas need extrinsic, committed necessity.The distinction between these two MVs is not clearly-cut.Thus, must may shift to the function of need, and need may shift to the function of must, depending on the contexts of communication.
Scollon & Scollon (1995）indicate that MVs and MAs can be related to power or politeness in some cases.Hoye (1997: 66）claims that MAs co-occurring with MVs can draw the hearer’s or reader’s attention to the speaker or writer as the probable instrument or the source of opinion.Consider Figure 2.7:
(53）Perhaps you would like to reconsider or provide some justification for your statement.
In Example (53), the MA perhaps draws the hearer’s or reader’s attention to the attitude or judgment conveyed by the MV would.To Hoye (1997: 130-131), the speaker or writer uses MAs as a means of positive politeness or “involvement” on some occasions, but as a means of negative politeness or social distance or power on other occasions.Consider the following:
(54）Could you possibly tell me the way to the library?
(55）My lord, may I very respectfully at this stage explain what this man did?
The two MAs possibly (co-occurring with the MV could）and respectfully (co-occurring with the MV may）in Examples (54）and (55）both show negative politeness, or the social distance between the speaker and hearer.Therefore, like MVs, MAs can be socially significant and can be analyzed from the perspectives of social settings or communicative functions.Myers (1989), Hyland (1996, 1999), Ivani? (1997), and Thompson (2001）discuss the use of the co-occurrence of modal devices (including MVs and MAs）as a means of politeness strategy for negotiation within academic communities.
The linguists studying modality at the discourse level by means of the functional representation approach suggest that modal devices are sometimes indispensable for successful communication.The social settings involved could be varied in terms of the relationships between addressers and addressees.The main functions of modal devices are: (a）highlighting or reducing the difference of social status between addressers and addressees; (b）facilitating negotiations.
2.1.5.3 Typology and evolution levels
Some linguists study the functions of modal devices according to typology and linguistic evolution.They indicate that modality is common in many languages and modal senses are a result of evolution.
Bybee & Fleischman (1995）offer a wide-ranging study of MVs by comparing and contrasting many languages.Brandt (1999）compares the use of MVs between English and Danish, offering a detailed description of how modality works in a cognate but not widely known Germanic language, i.e.Danish.Brandt (ibid）holds that three classificatory dimensions of modality seem to work universally: modal source, modal intensity and modal orientation.Modal source may be implicit or explicit; modal intensity is the strength of the speaker’s commitment in terms of a tripartite scale: possibility, predictability and necessity; modal orientation refers to the distinction drawn between active and passive modality.Palmer (2001）gives a study of modality through typological comparing and contrasting.For instance, Palmer (2001: 103）points out the similarity of MVs between English and Greek:
Although the same modal verbs may be used in English for both epistemic and deontic modality, generally the distinction is quite clear, and it can be seen…that there are also some formal distinctions between the modals in their two uses: (i）Deontic MUST has negative mustn’t and a suppletive needn’t, but epistemic MUST has no morphologically related negative; (ii）May not negates the modality when deontic (no permission), but the proposition when epistemic (‘It may be that it is not so’); (iii）MAY and MUST followed by have are always epistemic, never deontic; (iv）MAY is replaceable by CAN only in the deontic use, though can’t may be epistemic.Furthermore, when it refers to the future, MUST is almost always deontic; the epistemic sense is provided by BE BOUND TO.Moreover, might is closely related in its meaning to the present tense may only in its epistemic sense.In Modern Greek, similarly, although the same forms are used for deontic and epistemic modality, there are differences in the syntax…