In sentences such as the following, there is (as I understand it) an infinitive clause and an infinitive phrase. Which part is the infinitive clause and which part is the infinitive phrase? And what is the subject?


One thing to do about this is to stop feeding animals junk food.

One way to improve your dancing skills is to practice on a hot tin roof.

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    Both sentences contain subjectless infinitive clauses. The first clause in each is a relative infinitive clause (modifying thing and way), and the second clause in each is a noun complement clause. Neither one is a phrase; they're all clauses. And they are all missing a subject. But the subject is reconstructible, as usual. All of the subjects are indefinite (though the second one uses you and may in fact refer to the addressee instead of a generic person). Mar 15, 2014 at 0:10
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    No, thing is the head noun of the subject NP, but the subject of the sentence is in fact the whole NP One thing to do about this. Calling thing the "subject" just confuses the issue when it's also the object of do in the infinitive clause. Mar 23, 2014 at 19:38
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    @Araucaria: No. Clauses represent propositions and have subject and predicate, in English at least. Phrases are other constituents, including individual words (I is a noun phrase for instance). Infinitives and gerunds are always clauses in what generative grammarians call "underlying structure", but a number of rules conspire to move or remove their subjects in "surface structure", so all that's left is a verb phrase. Oct 13, 2015 at 14:04
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    That's an alternative way of handling it; but what I described is the way that's evolved in practice. It keeps the focus on the individual cycle. McCawley is pretty good on the cyclic principle, by the way. It's a really productive part of grammatical theory. Oct 13, 2015 at 14:25
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    Constituent refers to clause- and phrase-level items, as well as individual words. What it excludes is strings that are not complete constituents, or that consist of parts of more than one constituent. It's important because it turns out that syntactic processes only apply to constituents. "Phrase" is indeed the normal combining form -- NP, VP, PP, etc. But not SP. Oct 14, 2015 at 2:06

4 Answers 4


There is no clause in the sentences. The first infinitives in both sentences are adjectival which cannot be separated from the noun phrases which begin the two sentences to form the subjects of to be verbs is and is respectively. The second elements after to be verbs are infinitive phrases which perform the functions as the complements to the subjects. There is no clause among the infinitives because there is no finite verb in them all.

From Idoko, Ejike Celestine (Celestial Academic Centre)


Modern grammarians consider such constructions clauses, not phrases. What traditional grammarians called infinitive phrases are now called infinitival clauses, a type of nonfinite clause.


One thing to do about this is to stop feeding animals junk food. Subject, placed at the end: to stop to feed animals junk food - to stop something: to-infinitive + object - object replaced by: infinitive phrase Verb, linking verb: is be-complement: one thing to do about this to do about this: a sub-element of: a thing

to practise on a hot tin roof: subject, placed at the end

is: linking verb

one way to improve your dancing skills: be complement

to improve your dancing skills: infinitive phrase, sub-element of: one way


Modern is as Modern does, so forever shall confusion reign!

A phrase used to be a phrase, a clause used to be a clause, and a sentence used to be a complete thought. Those days are long gone! There are now so many re-interpretations of so many supposedly 'pointless and useless' grammar rules that everything that used to be known is known no longer. I can not see any progress in how students are taught English compared to how it used to be taught many decades ago.

English Grammar should never have become interpretative. It should be learned and used to interpret the meaning of sentences, and those sentences should be complete thoughts; else, what's the point?

Grammar should be learned from older books, and newer books should be used to create lists of newfangled terms simply so that you can pass a test. There are too many confused students. What do modern grammerians have to say about that? Good Luck. I suggest that you go to google books online and download free ebooks by Reed & Kellogg. They are clear and concise. Believe me, there's nothing new in grammar, just new opinions that confuse the people.

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