Specific English word classification

Question

I'm looking for a maximum subset of the English language such that words can be divided into two categories, one of which must include at least nouns, proper names, adjectives, numerals, verbs and adverbs, and the other must include at least the articles ('a', 'the'). Each of the groups may, and should, include other words, like different kinds of pronouns, etc.

It is OK to omit some words if they cannot be placed in one of the two categories (sacrificing the expressive power of the resulting subset of English). For example, if "will" the noun and "will" the verb, or "mine" the noun and "mine" the possessive pronoun fall into different categories, they may be omitted (yes, even sacrificing the whole future case is tolerable).

It wouldn't be hard if there were no constraints, would it? The division has to be natural (intuitive for a native speaker; words in the first group should be considered substantially more "significant" than words from the second one) and unambiguous: no word with the same spelling should fall into both categories, regardless of position in the sentence, part of speech, etc.

Answer 1

Some additional contributions of mine:

Stressed vs unstressed:

Nouns, adjectives, lexical verbs, numerals and adverbs in English all carry primary stress, whereas articles don't. Prepositions will go into either category ('of' to the second class, 'over' to the first class).

Counterexample: The only one I can think of is that auxiliary verbs are unstressed, but you want them in the first category.

Bound vs. free:

Words in the first class may stand alone in a phrase:

(1) [NP [N Humans]] are [AP [A smelly]].
(2) [NP [PN John]] is smelly.
(3) I've got [NP [# one]].
(4) Humans [VP [V smell]].
(5) I [VP [Aux will]].
(6) He [AdvP [Adv really]] smells.

English articles, like articles in most languages, are bound forms and can't appear alone:

(7) *That's [NP [Art the]]/[NP [Art a]].

In the end you may end up needing a combination of the criteria proposed to get your classes.

Answer 2

Yielding roughly the same as the distinction between open and closed word classes, but from a more functional perspecive rather than w.r.t. productivity (i.e. how frequently are new words form based on their class, as is the case in the open vs. closed classification) is the distinction between content words and function words:

• content words are mostly nouns, verbs, adjectives and adverbs.
  They usually refer to predications (i.e. properties of one individual or relations between several individuals) over concrete entities in the world, such as "is a dog", "sleeps", "is red", "loves Mary" or predications over predicates (such as "slowly" which modifies some moving event, which can again be seen as a predication over entities).
  Of course, abstract nouns such as "theory", which do not really refer to a concrete entity, mass nouns such as "water" which can not discretely be counted or some other problematic cases do belong to this category too, but speakers have quite good intuitions about these words still belonging to the category "noun".
  Since content words are used to refer to something in the actual word, they are rather productive, i.e. you can always invent new words (or build them up from existing ones) to fit the language to the circumstances you want to describe, such as "bus stop" ("bus" + "stop").
• function words comprise, roughly, categories such as articles, quantifiers, pronouns, adpositions, conjunctions and subjunctions, and are words that do not predicate something in the world but are rather there to express functional aspects such as relations between sentences and phrases ("and", "or", "if", "because", ...), quantification (such as "a", "2", "many", ...), reference ("he", "there", "then", ...), interjection ("yes", "no", "hey", ...) and others.
  Since the set of concepts such as logical relations, quantities etc. are rather limited, the set of function words corresponds more or less to the set of closed class words, as new expressions are rarely invented.

Note that, although languages may vary in the size and distribution of their lexical inventory (for example, some languages may have adjectives that behave very verbal and in which adjecties might not be seen as a separate class, or numerals which have more properties of a noun than of something determiner or adjective-like, or a rather productive and open-class set of adpositions, ...), the basic distinction between content words and function words, as well as the correponding word classes, is something more or less universal, and not specific to the English language.

Answer 3

There is indeed some kind of classification along the lines you sketch, it is open versus closed word classes.

• Open classes easily accept neologisms and contain a lot of different words
• Closed classes contain a usually small number of fixed words and are resistant to neologisms

Note that the notion of open and closed word classes depends on the language you are looking at. There are language outside where the pronouns are an open class and there are languages where adjectives or verbs are a closed class.

For English, the closed classes are articles and determiners, pronouns, prepositions, conjunctions, and particles (words like "yes", "no", "not").