Figure 2.5 clearly indicates that evidentiality is a matter of interaction between sources of knowledge and cognition, and that the knowledge thus yielded is a product that contains such elements as certainty and expectation.Put in another way, evidentiality stems from the interaction between sources of information and thinking, which in turn becomes a way of conveying attitudes or ideas.Whether the attitudes or ideas expressed are appropriate depends on the knowledge gained.Hu (ibid）argues that modal devices are important means of evidentiality.
Boye (2005: 71-72）claims that evidential linguistic items as expressions of (types of）sources of information are often easily distinguishable from modal linguistic items.The evidential meaning of the adverb allegedly, for instance, has nothing to do with necessity, disposition and possibility, nor, of course, with deontic and dynamic meaning; in many languages, evidential and (epistemic）modal meanings are encoded in different categories or paradigms.
However, Boye (ibid）also mentions that the meaning domain of evidentiality and the epistemic variant of the meaning domain of modality are closely related.First, epistemic modal linguistic items and evidential linguistic items are semantically both concerned with the truth of a predicational content.Second, epistemic modal meaning and evidential meaning both involve the idea of an epistemic source.Third, in some languages epistemic modal linguistic items and evidential linguistic items belong to the same category or paradigm.Fourth, modal meaning and evidential meaning are both organized on the intensity scale.Fifth, in certain contexts, epistemic variants of modal linguistic items encoding the meaning of strong modal intensity may have weak or indirect (reported or inferential）evidential meanings.
MAs are the means of evidentiality like MVs in many cases.Nuyts (2001: 56-57）holds that many MAs (e.g.seemingly, apparently, and clearly）express inference as an evidential dimension, i.e.they all somehow mean that “from what is known it can be inferred that…,” but at the same time they seem to express an epistemic evaluation as well.Therefore, the borderline between epistemic and evidential forms may not be sharp.The value of MAs is two-layered.Just as cultural and cognitive linguists believe that evidentiality can be scalar, some scholars of pragmatics argue that MAs can be scalar as well.Levinson (1983: 134）scalarizes MAs in a descending order as: and .
It is interesting to notice that even some Structuralism supporters such as Lyons use the evidentiality method to study MVs.Lyons (1977: 798）distinguishes subjective modality from objective modality by showing that may in Alfred may be married can express the one or the other depending on the context in which it is used.Saeed (1997）terms such a semantic approach as cognitive semantics.Obviously, Lyons implies that the MV may indicates subjective modality if it is regarded as a prediction based on supposition, but objective modality if it is regarded as a judgment based on sound evidence.
In general, it can be found that the evidentiality method does not deny the double functions of modal devices, i.e.expressing attitudes (or judgments）and offering evidence for opinions.
The approach of pragmatics shows that the use of modal devices for indirect speech acts or evidentiality is feasible, and sometimes indispensable in discourse for successful communication.To some extent, this approach does consider or suggest the co-functions of pragmatic inputs and cognition.
2.1.5 Functional representation
The approach of functional representation tackles modal devices from their functions in clauses, social settings, and discourse, and includes a number of linguistic schools, such as the Dutch Functional School, diachronic linguistics, and corpus linguistics.
2.1.5.1 Clause level
Some linguists explore modality at the clause level by means of functional representation.They reveal what adverbs perform modal functions and what positions modal devices enjoy at the clause level.
The Dutch Functional Grammar assigns MVs and MAs to the category of operators in clauses.In Dik (1978）and Vet (1998: 1-23), each clause is layered in structure as follows:
A.Nuclear Predication (event type)
B.Core Predication (modified event type)
C.Extended Predication (state of affairs)
D.Proposition (possible fact)
E.Clause (speech act)
Modal devices are parts of the core predication.Each clause comprises a pragmatic module and a grammatical module; the utterance content is represented in the grammatical module while the speech act is included in the pragmatic module.MVs and MAs as operators belong to the pragmatic module.The Dutch School, using a deive and formalism method, designates MVs and MAs as yielding pragmatic value in communication.
Greenbaum (1969）classifies adverbs into conjuncts, adjuncts and disjuncts.Adjuncts are normally those adverbs modifying verbs, conjuncts link sentences, and disjuncts convey attitudes over propositions.Sometimes, adverbs can act as both disjuncts and adjuncts.Greenbaum’s classification can be charted as follows in Figure 2.6.