Modal words are morphologically unchangeable words that function as parenthesis and express the correlation between the content of an utterance with the real-world situation as seen by the speaker. Therefore, modal words are treated as a lexico-grammatical means of the category of modality.

One of their specific properties is that modal words are predominantly derived from other parts of speech. This fact is often used as an argument to deny modal words their independent lexico-grammatical status of a part of speech.

Though Western linguists, particularly authors of classical scientific grammars, pointed out specific characteristics of some adverbs and of their syntactic functions, which led them to define these units as sentence modi­fying adverbs or modal adverbs (these points of view may be found in works by Henry Sweet and Hermann Poutsma respectively), modal words as a separate part of speech was first distinguished by Russian linguists.

Howev­er, even nowadays there is no unanimity among scientists as to their status, since modal words exhibit a diverse morphological and syntactic structure and since they may belong to different language levels: separate words, on the one hand, and word combinations or even sentences, on the other hand. However, a number of scientists point out specific semantic and syntactic properties of modal words, with the latter being particularly important for an analytical language. These properties are regarded as sufficient argu­ments to support the status of a separate part of speech. Proponents of this point of view differ in their opinion as to the place of modal words in the modern English morphological system: some of linguists refer this class to lexical parts of speech, others stress that this class is still developing and has not been completely formed. It is remarkable that none of the mentioned viewpoints is based in the presumption that modal words are in fact function words.

The set of English modal words has not been defined yet. As a rule, the words actually, apparently, assuredly, certainly, clearly, of course, de­cidedly, definitely, evidently, indeed, maybe, naturally, obviously, perhaps, positively, possibly, presumably, probably, really, seemingly, supposedly, surely, truly, undoubtedly are treated as modal as well as obsolescent for­sooth, mayfall, mayhappen, meseems, methinks, peradventure, percase, per­chance, verily used by some authors for stylistic purposes to convey peculi­arities of a certain historical period.

There is no established semantic classification of English modal words, but scholars usually mention two following semantic classes: 1) words eval­uating the content of an utterance as a fact, and 2) words evaluating the con­tent of an utterance as something possible, presupposed or impossible.

Modal words within these two classes undergo a further subdivision. For example, the first subclass is grouped around the word certainly and includes assuredly, of course, indeed, surely, whereas the nucleus of the second subclass is obvious with apparently and evidently expressing the same meaning.

The second semantic group of modal words may be divided into three subclasses: modal words expressing possibility {possibly, probably), those of presupposition (seemingly, supposedly), and those of doubt (maybe, perhaps).

Morphological structure of modal words is of two types: English mo­dal words may be either derivatives (possibly, really, supposedly) or com­pounds (indeed, maybe). It is also noteworthy that the latter group contains such elements as of course that, though formed by a preposition and a noun and spelled separately, is treated as a modal word.

The mentioned structural types of modal words are characterized by their own derivational types and functions. For instance, modal words de­rived from adverbs develop lexico-semantically, i.e. an adverbial lexeme is split into an adverb and a modal word. As a result, the adverb-forming suffix -ly in modal words is not regarded as derivational in modal words.

Modal words in English – Part 2