According to this ThoughtCo. article titled "NICE Properties of Auxiliary Verbs":

NICE is an acronym for the four syntactic characteristics that distinguish auxiliary verbs from lexical verbs in English grammar: negation, inversion, code, emphasis.

The NICE properties were identified as such by linguist Rodney Huddleston in the article "Some Theoretical Issues in the Description of the English Verb" (Lingua, 1976).

I won't be explaining in detail what the NICE properties are, because they're fairly straightforward. If you're not familiar with them, please visit the link above for reference.

Here are some NICE property examples shown in The Cambridge Grammar of the English Language (page 93):

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In the above examples, only finite auxiliary verbs are shown to have the NICE properties. Do non-finite auxiliary verbs too have the NICE properties? If the NICE properties are "the four syntactic characteristics that distinguish auxiliary verbs from lexical verbs in English grammar", I think non-finite auxiliary verbs (as well as finite auxiliary verbs) should have the NICE properties. But they don't seem to.

Here are my failed attempts at producing NICE property examples of non-finite auxiliary verbs:

(1) Not having seen it, he had no clue. [Negation]

(2) N/A [Inversion]

(3) He may have seen it and I may have. [Code]

(4) ??They don't think he has seen it but he must HAVE seen it. [Emphasis]

In (1), not typically comes before having rather than after. It's not clear whether the not coming before having should be considered as negation of having. But let's assume for the moment that it should. Also, some speakers might put not after having, in which case not does negate having. It's possible, therefore, to argue that the non-finite auxiliary having does have the Negation property.

I can't think of any examples for (2) because there's no subject-auxiliary inversion in non-finite clauses.

In (3), although some speakers may choose to omit the second have, at least for those speakers who allow the second have, it can be said that the second have, a non-finite auxiliary, has the Code property.

In (4), it's unlikely that you could pronounce HAVE emphatically.

All in all, however hard I try, non-finite auxiliaries cannot seem to allow the Inversion and Emphasis constructions, which means that non-finite auxiliaries don't seem to have the NICE properties.

If non-finite auxiliary verbs don't have the NICE properties, which they don't seem to, is it really correct to say that the NICE properties are "the four syntactic characteristics that distinguish auxiliary verbs from lexical verbs in English grammar"?

  • 1
    You'd probably get more response if you added examples. And one can foresee the simple addition of a 'other than when used in non-finite clauses' caveat rectifying any potential problem. All useful laws in English, except this one, have exceptions. May 23, 2020 at 13:45
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    @JK2 I agree with Edwin Ashworth: the thrust is that it would be extremely useful for you to give examples of auxiliary verbs in non-finite clauses
    – Greybeard
    May 23, 2020 at 14:09
  • @Greybeard I don't think either Edwin or you (or anyone who's competent enough to answer the question, for that matter) don't fully understand the question for the lack of examples. But I'll edit the question to include some.
    – JK2
    May 23, 2020 at 14:20
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    Your wrong example is itself wrong; it must instead be “He saw it not. Think of the old children’s rhyme intoned while plucking off the petals of a daisy one by one: “She loves me, she loves me not; she loves me, she loves me not.” This demonstrates how, especially poetically or archaically, the postposed negative always follows the object; it interposes itself never between the verb and its object. This then is why your wrong example is wrong: not for its mere post-positioning of the negative, but rather for its syntactically forbidden interposition of same.
    – tchrist
    Apr 19, 2023 at 14:21
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    @tchrist First, it's not my example. It's CGEL's example. Second, just because you can say she loves me not doesn't mean you can also say He saw it not in Present-day English. So I don't get your point.
    – JK2
    Apr 19, 2023 at 23:49

2 Answers 2


From a syntactic point of view, auxiliary verbs are verbs in that they conjugate (I am, he has, she did) and mark tense when necessary (i.e, in tensed clauses where they appear first), and auxiliaries because they have no intrinsic meaning except to mark constructions like Passive, Progressive, or Predicate Nouns; and they appear wherever they are required by some rule or construction and not elsewhere.

(Syntacticians say auxiliaries are "inserted" by the rule or construction, but what we really mean is they're necessary to the machinery, like the dummy it in Extraposition, or the to on most infinitives.)

The property of "Negation" appears to mean that some kinds of negation require an auxiliary verb (which is usually contracted, with the negative or with a subject NP).

  • Bill is/isn't tired. ~ Bill has/hasn't left. ~ Bill must not have left.
    (with auxiliaries already)
  • Bill likes cilantro, but *Bill not likes/likes not cilantro
    (without auxiliaries, so negation not grammatical)
  • Bill does not (doesn't) like cilantro
    (with Do-support when there isn't an auxiliary to hand)

That's a property of negation of a particular sort, with not directly before the verb chain. Other types of negation don't require auxiliary verbs; it's only this one type of negation. So it's not really a property of auxiliary verbs, it's just another rule-based use for them.

  • Bill dislikes cilantro ~ Nobody in my family likes cilantro.

"Inversion" is a property of the rule of Question Formation. Forming a question in English usually involves inversion of the subject and the first auxiliary, and thus requires an auxiliary verb. Again, if there is none, do is supplied. But this only works for questions, and only when they're not embedded -- complement questions are not inverted.

  • Bill works for Boeing ~ Why does Bill work for Boeing?
  • I wonder why Bill works for Boeing, but not *I wonder why does Bill work for Boeing?

So "Inversion" is another use for auxiliary verbs, not a property. The property is associated with the rule that determines it, in this case, question formation.

"Code" appears to refer to deletion rules, like Conjunction Reduction. Again, this is a property of the rules governing the deletions, rather than auxiliary verbs themselves. The point here is that the first auxiliary verb in a clause can represent the entire verb phrase (and the entire clause when untensed) in sentences where deletion rules have occurred.

I would prefer a term like "pro-verb" for this, as pronoun parallels noun. That's what it's doing, and the term "Code" is not a helpful mnemonic -- EVERYTHING in language can be (and has been) called a code.

Finally, "Emphasis" is related to the pro-verbal use of auxiliaries. They can be stressed, effectively reduplicating the verb. Of course, this is not true just of auxiliaries. Any verb can be stressed, and stressing auxiliaries adds to the effect. So, yes, it's another use for auxiliary verbs; they do have a lot of uses, just like prepositions and pronouns and other nuts and bolts.

But they're all handled by the rule machinery.

  • 1
    You say, "From a syntactic point of view, auxiliary verbs are verbs in that they conjugate (I am, he has, she did) and mark tense when necessary (i.e, in tensed clauses where they appear first)...", but the same can be said about lexical verbs: they conjugate (I live, he lives, she lived) and mark tense when necessary (i.e, in tensed clauses where they appear first). Moreover, auxiliaries don't have to conjugate or mark tense (I'll be there, he'll have finished it by now).
    – JK2
    Apr 20, 2023 at 5:53
  • Well, yes, of course. Those are properties of verbs, which makes them verbs (there's a long-standing argument about whether be should be called a "verb" or not; I think it should, for these reasons). Following those properties of verbs that apply to them, I listed properties that are unique to auxiliary verbs, as a specialized (and rapidly changing) subset in wide use. Sorry to confuse you. I probly should have used more boldface to contrast them, or something. Oh, and I said they conjugate, not they always conjugate. They conjugate when they're sposta; they're verbs. Apr 20, 2023 at 16:04
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    Somehow unbeknownst to you, 'NICE' has "become popular". Most recent serious discussions of English auxiliaries do mention 'NICE' or some variant thereof. For example, Modality and the English Modals, Second Edition by F.R. Palmer has a subsection titled "the NICE properties" on page 201. See the contents: books.google.com/…
    – JK2
    Apr 21, 2023 at 22:42
  • 1
    Why is that relevant?
    – JK2
    Apr 22, 2023 at 0:10
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    Inversion happens in a wide range of environments, for example when a finite clause is preceded by a negative (or should I say negating) adjunct, or one using only: "Only if ... will she ...". Also conditional protases etc. Apr 24, 2023 at 14:08

*I sold the car, sold not I?

I sold the car, didn’t I?

*Sold I a car?"

Have I sold/Did I sell a car?


I have a car, haven’t I?

I have a car, don’t I?

Have I a car?

Have I had a car?

Did I have a car?

is it really correct to say that the NICE properties are "the four syntactic characteristics that distinguish auxiliary verbs from lexical verbs in English grammar"?

There are no absolutes in English. Huddleston seems to have made a list of the usages of auxiliaries and then created "Rules" around these by noting patterns. As you will see from the site to which you link, there will be exceptions.

(1) Do auxiliary verbs in non-finite clauses have the NICE properties?

In (1) Not having seen it, he had no clue. [Negation]. The question seems pointless. Whereas in

(i) I saw it, and (ii) "I have seen it" we have (i) SVO and (ii)S-Aux-pp-O, there is no subject and verb to be inverted:


(ii) *"I saw it not", and "I have not seen it", we have (ii) an error and (iia) S-Aux-{adv-pp}-O

but there is no subject - verb to invert:

(iii) "Having seen it, ..." and "Not having seen it, ...." We have [Adv]-Aux part- past p.-O

but we can also say

(iiia) "Having not seen it, he had no clue." but (iiib) *"Having seen not it, he had no clue." (Although "Having seen not it, but something else, he had no clue." is correct.)

(3) He may have seen it and I may have. [Code]

The auxiliary is "may" - the second infinite "have" can be omitted.

(4) ??They don't think he has seen it but he must HAVE seen it. [Emphasis]

Must is the auxiliary.

  • In (3), I know that have can be omitted. But have there is the only non-finite auxiliary. In (3) and (4), may and must are the only finite auxiliaries, so I've discussed the non-finite auxiliary have. So even if you're right about NEGATION, the non-finite auxiliaries still don't have the NICE properties.
    – JK2
    May 24, 2020 at 0:25
  • In British English, I think have has the NICE properties. A: Have you a car? B: No, I haven't. A: That's not true. You HAVE a car. Whether to view this British have as an auxiliary or as another piece of evidence that auxiliaries don't have the NICE properties is a different question, I think. // Also, I've edited the question to accommodate your answer.
    – JK2
    May 24, 2020 at 2:59

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