What's quasi-modal be?

Question

What's quasi-modal be? It is not a traditional grammar term. Google says

You are to be good. <=> You must be good.

1. Other than obligation, what modalities can the quasiness refer to?
2. What characteristics separate it from auxiliary and lexical be?

Answer 1

The key thing to remember about “modal” constructions is that modality refers to operating in both the epistemic mode of predictions and possibilities as well as the deontic mode of obligations and permissions. Anything modal can always go either way.

The modal verbs in English are will, would, shall, should, can, could, may, might, and must. They all enjoy the same special rules of how they syntactically combine with bare infinitives and how they behave under inversion and negation. They are also all morphologically defective in themselves lacking infinitives, participles, -s inflections for person, and apart from backshifting also tense.

But these are not the only verbal expressions with modality in English. The other kinds are still modal in that they too can always take on both the probability modality as well as the obligation modality. They differ from the true modals in one or more of the special syntactic and semantic properties enjoyed by the true modal verbs. That’s what makes them only “semi-” or “quasi-” modals.

A few of these are quite close to actual modals in all properties, like ought to and in some dialects ought not, as well as dare not and need not.

But most of these quasi-modals are periphrastic ones: multiword combinations using an inflected verb that convey the same meaning. Doing this frees them to take on the many properties forbidden to the true modals.

Like its brethren (to) have to meaning must, (to) be able to meaning can/could or may/might, and (to) be going to meaning will/would, the periphrastic modal (to) be to meaning will/would also maps to one of the true modals but inflects for person and tense and is not barred from having infinitives and participles. But it no longer takes a bare infinitive, which is why in all three of those I’ve included the mandatory to following it.

The true modal which the periphrastic modal be to most closely emulates is will, and just like will it more often does so in the epistemic modality of prediction than in the deontic modality of obligation. But both modalities are still open to it, just as they are with will.

Mode 1: Epistemic modality

1. John will join them for dinner tonight.
2. John is to join them for dinner tonight.

Mode 2: Deontic modality

3. All children will wash their hands before dinner.
4. All children are to wash their hands before dinner.

Even when you backshift all of these as you do for reported speech or use a perfect to indicate a completed event, both modalities are still possible, with the probability mode still somewhat more likely than the obligation mode. Negation can alter those, however.

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See also these answers by John Lawler:

1. Is "have to" a modal verb?
2. What do you call 'be-to' constructions and are they acceptable English?
3. "Was to" vs "was to have"

Answer 2

I

What's quasi-modal "be"? It is not a traditional grammar term.

"Quasi modal" has to be just another term for what is called "modal idiom" in A Comprehensive Grammar of the English Language (Quirk et al, 1985). In this grammar this verbal form is not "be", but "be to".

In the auxiliary-main verb scale those modal forms come after the central modal auxiliaries and the marginal modals.

(CoGEL, Fig 3.40a) The auxiliary verb-main verb scale

(a) CENTRAL MODALS          can, could, may, might, shall should, will/'ll, would/'d,                                                       must
(b) MARGINAL MODALS       dare, need, ought to, used to
(c) MODAL IDIOMS            had better, would rather/sooner, BE to,                                                      HAVE got to, etc.
(d) SEMI-AUXILIARIES         HAVE to, BE about to, BE able to, BE bound to,                                                        BE going to, BE obliged to, BE supposed to, BE willing to,                                                         etc
(e) CATENATIVES                    APPEAR to, HAPPEN to, SEEM to, GET +-ed participle                                                        (user LPH: of course irregular participles also ("I get stuck                                                        in the traffic every time.))
(f) MAIN VERB +
nonfinite clause                        HOPE + to-infinitive, BEGIN + -ing participle, etc

(CoGEL § 3.45) Modal idioms: had better, etc

This category contains the following four multi-word verbs, as well as some less common verbal constructions:
         had better,          would rather,            HAVE got to,       BE to

They all begin with an auxiliary verb, and are followed by an infinitive (sometimes preceded by to):

• We had/'d better leave soon. Yes we had/'d better. [1]
• I 'd rather not say anything.[2]
• They 've got to leave immediately. [3]
• The conference is to take place in Athens. [41]

None of these idiomatic verbs has nonfinite forms; they cannot therefore follow other verbs in the verb phrase:

• *I will have got to leave soon.
• *The conference has been to take place in Athens.

In this respect they are not like main verbs. They are not, however, entirely like auxiliaries, since they do not behave as operators. It is normally the first word alone which acts as operator in (for example) negative and interrogative sentences :

• Hadn't we better lock the door?
• Would you rather eat in a hotel?
• We haven't got to pay already, have we?
• I wasn't to know that you were waiting.

(From CoGEL § 3.40, Verbs of intermediate function) There can be made out a gradient among certain verbs of status intermediary between auxiliaries and main verbs, and those concern generally modality; the six categories above ((a) to (f)) show this scale from the most typical modals at the top to the least typical at the bottom. It is not usual to refer to the three last categories as modals. The extremes of the scale may therefore be represented by I can go and I hope to go. The structural implication of this scale is that the construction (a) I can go contains one verb phrase, whereas the construction (f) I hope to go contains a finite verb followed by a nonfinite one.

First of all, as an auxiliary (independently of the particular sort—aspect ("they are working"), voice ("they are pushed away by the wind"), modality ("they are to be left alone")—"BE to" should satisfy to some of the 8 defining characteristics that apply to auxiliaries. It satisfies to at least 6 of them.

1. Operator in negation with not       • You are not to go there alone. • *You go not there alone¹.
2. Negative and verb contraction This is true only for "are" not for "am"       • You aren't to go there alone. • I am not to go there alone. (user LPH: the negative interrogative seems very rare ("Aren't you to go there alone?").)
3. Operator in inversion • Are you to go there alone? • *Go you there alone?
4. Emphatic positive I shouldn't go there alone. • You Àre to go there alone. (user LPH: the possibility of this stressing is unsure as far as I know, and any native speaker who can confirm or infirm this fact with certitude is welcome to complete this part.)
5. Operator in reduced clause (user LPH: Here again I am unsure as to this possibility. Sentences such as "I am to go there alone if you are." do not seem usual at all and confirmation by a knowledgeable native speaker is needed.)
6. Position of adverb • You are never to go there alone. • *You go never there alone.
7. Postposition of quantifier • You are all to go there alone. • *You go all there alone.
8. Independence of subject • A winner is to be chosen among them. • There is to be chosen a winner among them.

"BE to" can be said to have the nature of an auxiliary; as concerns the nature of of a modal auxiliary, the same cannot be said.

1. It is not followed by the base form of a verb but by a to-infinitive, unlike central modals.
2. It does occur in the infinitive ("Here are folders to be considered later.")
3. It does have an -s form ("is"), unlike modals (central and marginal).
4. It does permit normal tense references ("He is to come presently" (present), "He is to come back shortly" (near future), "He was to come back but never did" (past)), and this is not at all the case for the true modals.

It is clear then that morphologically and syntactically "BE to" is not a modal, yet syntactically (combination of two verb forms) and semantically, it is apparented to one.

II

Other than obligation, what modalities can the quasiness refer to?

What modality other than obligation is the function of this modal idiom is well answered in the SOED (The Shorter Oxford English Dictionary).

III As auxiliary verb 11 With infinitive, express duty or obligation (often replaced by have), intention, possibility, destiny or hypothesis.

• S. RICHARDSON I am to thank you for your kind letter. (user LPH: duty)
• DICKENS You was to come to him at six o'clock. (user LPH: obligation or intention)
• E. A. FREEMAN Normandy was to be invaded on each side. (user LPH: intention)
• J. CONRAD He was nowhere to be seen. (user LPH: possibility)
• R. A. KOX It wasn't for him to mix himself in political quarrels. (user LPH: destiny)
• (added by user LPH: U.N. Third Conference on the Law of the Sea (resumed 10th session) If the system is to work, it will be essential to ensure that the Enterprise is truly viable. (user LPH: hypothesis)

III

What characteristics separate it from auxiliary and lexical be?

What characteristics separates it from lexical "be", which has essentially the characteristics of an auxiliary, that is the 7 first characteristics of an auxiliary shown above, is the fact that it permits the independence of subject (8) and that it is not allowed (probably) to use with it emphatic stress (4) ("You are not ready. I Àm ready.") and to use it as an operator in reduced clauses ("She is not often depressed but when she is she has to take a lot of pills.")

Note ¹ *: not acceptable