the to-infinitive as an adverbial(substitute of for+N?), an object, or a subject complement?

A. She is likely/sure/certain to start her new project.

She may start her new project.

Are the senses and the roles of the to inf. the same as 'start her new project' of 'may', complementing the (modal) verbs and indicating the action of the subject? Do we speak them in the same sense? If we classify the main verb of modal verbs ad the complement of the modal verbs, do we also classify the inf. above as the complements of the 'be + adj.'s? Or is the to-inf. just an object?

B. I'm dying/willing/curious/anxious/eager to eat that cake.

I'm dying/willing/curious/anxious/eager for that cake.

Do we speak the to inf.s above in the same sense as the 'for~'s? Do they mean the same, expressing the subject's wish, desire, or plan as adverbials?

C. I hoped for some money./I hoped to take the train.

I begged for more candy./I begged to go to the movies.

I longed for an A./I long to get an A.

I volunteered for the job./I volunteered to help the kids.

I was aiming for the trophy./I was aiming to receive the trophy.

Do these to inf. express desire/intention as adverbials, same as the 'for+N's? Or, are they just objects?

Solution 1:

Though you're correct that many of the pairs you've provided are similar semantically, you've confused the functions complement, object, and adjunct(traditional grammar's 'adverbial').

First off, you'll want to get form and function separated. The form of dependent clauses, and phrases, is determined by their internal structure: NPs are headed by nouns and allow a certain range of dependents; to-infinitival clauses are headed by a verb in plain form and allow a range of dependents different from those found in an NP. So, a to-infinitival clause will never be an NP, but it may appear in the same functional category in a larger structure.

Then, you can start to look at the function of these dependent clauses and phrases in clause or phrase structure.

I

She - is - likely [to - start - her new project]

Subject - predicator - predicative complement

vs

II

She - may - [start - her new project]

Subject - predicator - catenative complement

In I, to start her new project is a to-infinitival clause functioning as dependent (specifically a complement) in the adjective phrase headed by likely. It is a complement because it is allowed only by likely and other adjectives allowing a to-infinitival clause as complement, not by adjectives in general: *dry to start her new project.

In II, start her new project is a plain infinitival clause functioning as direct dependent (specifically a complement) of the predicator may. The specific type of complement is a catenative complement. These are non-finite (plain infinitival, to-infinitival, gerund-participial, or past participial) clauses specifically allowed by the verb acting as predicator.

It is necessary to note here that the to-infinitivals in your examples are not adjuncts, but in fact complements in AdjPs in A and B, and catenative complements in C. This becomes clear when we note that in order may not be inserted while keeping the same meaning,

?I'm willing in order to eat that cake. (Willing to do what?)

I'm dying in order to eat that cake. (How terrible!)

etc.

*I hoped in order to go to the movies.

I begged in order to go to the movies. (What did you beg for/to do?)

*I long in order to get an A.

I volunteered in order to help the kids. (What did you volunteer for/as/to do?)

I was aiming in order to receive the trophy. (What were you aiming at/to do?)

Though there is some overlap between verbs that allow different sorts of complement - object, catenative complement, predicative complement - the complements themselves are best viewed as distinct categories each allowed by a specific set of verbs. For example, what follows get in the each of the sentences below is a distinct sort of complement:

Mark - got - a dog [object]

Mark - got - excited to go one the trip. [predicative complement]

Mark - got - me - a dog [indirect object - direct object]

Mark - got - chosen as goalie [catenative complement(past participial clause)]

Mark - got - to go first [catenative complement(to-infinitival clause)]

Mark - got - me - to go first [object - catenative complement(to-infinitival clause)]

Though get allows these constructions, if we pick another verb that allows the first, say sniff, we'll quickly see that the others are not allowed.

Mark - sniffed - a dog [object]

*Mark - sniffed - excited to go on the trip. [predicative complement]

*Mark - sniffed - me - a dog [indirect object - direct object]

*Mark - sniffed - chosen as goalie [catenative complement(past participial clause)]

*Mark - sniffed - to go first [catenative complement(to-infinitival clause)]

*Mark - sniffed - me - to go first [object - catenative complement(to-infinitival clause)]

Though the last two could be understood as adjunct of purpose in some strange context, they are not understood in a sense similar to the catenative complement examples with get.

Long story short, yes all of the pairs you provided have similar meanings, no their structures cannot be analyzed as equivalent.