1. It is necessary for Mary to go home.

  2. It is necessary that Mary go home.

  3. It is necessary that Mary goes home.

I am wondering, what's the difference between their meanings?

  • What are you trying to communicate? What would be the situation? The first two are grammatical, but I'm having trouble envisioning a circumstance where any of them would be the natural thing to say. – WinnieNicklaus Aug 6 '14 at 14:08
  • 1
    Winnie appears to be trying to help you, Nima. You might consider replying to that comment. – Tyler James Young Aug 6 '14 at 16:01
  • Are you talking about parking a car, or going to a park? – CocoPop Aug 7 '14 at 14:08
  • everywhere. It is not important where he or she has to go. – nima Aug 7 '14 at 15:26
  1. It is necessary [for Mary to go home].

  2. It is necessary [that Mary go home].

  3. It is necessary [that Mary goes home].

I am wondering, what's the difference between their meanings?

ANSWER: It would seem that all three versions have the same meaning.

LONG VERSION: Your #2 and #3 versions involve mandative constructions. This is because "the adjective necessary . . . is restricted to the deontic kind of modality, so that it takes mandative but not non-mandative clauses" (see CGEL page 997, fn 21). Note that a mandative clause is a declarative content clause.

The difference between #2 and #3 is:

  • version #2 is a subjunctive mandative because the mandative clause is a subjunctive clause: "(that) Mary go home".

  • version #3 is a covert mandative because the mandative clause is an ordinary declarative content clause: "(that) Mary goes home".

and that difference is a mere syntactic one. There is no semantic difference. They both have the same identical mandative reading.

Before we compare your #1 version against the other two versions, let's first get some background info. On page 176-7 in the 2005 textbook ASITEG:

The meaning of mandatives includes a component of meaning comparable to that expressed by the modal auxiliary must (see Ch. 3, &8.1 on deontic modality).

And on page 54 in ASITEG:

Deontic modality expresses meanings relating primarily to what's required or permitted: this term derives from the Greek word for "obligation". . . .

  • The [b] examples are interpreted deontically: the meanings have to do with obligation or permission of various kinds. More specifically, the operative notion in [i.b] is obligation, in [ii.b] permission, and in [iii.b] a milder kind of obligation where it is a matter of what is the right thing to do. These notions all have to do with authority and judgement rather than knowledge and belief.

On page 997 in CGEL:

Within this framework, mandatives clearly involve deontic modality: . . .

With that above info in mind, let's now look at your version #1:

    1. It is necessary [for Mary to go home].

The adjective "necessary" is a lexical modal, and it is used for deontic modality.

There is an example in CGEL that is very similar to your #1 version. On page 207:

Necessary, necessarily, surely, etc.


  • i. It is necessary [that they be told] / [for them to be told]. - - [deontic]

  • ii. It doesn't necessarily follow that he's lying. - - [epistemic]

Necessary is used for objective deontic but not epistemic necessity; it takes a mandative or infinitival complement.

As you can see in the above [71.i] example, both the mandative and the infinitival alternants are there, and both seem to have similar, if not the same, semantic meaning (that's why they are alternants here, I'm assuming). The infinitival alternant is similar in structure to your #1 version.

And so, your #1 version (infinitival) has a meaning that is at least similar to your versions #2 and #3 versions (mandatives).

NOTE: CGEL is the 2002 reference grammar by Huddleston and Pullum et al., The Cambridge Grammar of the English Language (CGEL).

NOTE: ASITEG is the 1985 textbook by Huddleston and Pullum, A Student's Introduction To English Grammar (ASITEG).

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