Why use "need not" instead of "do not need to"?

Question

The header of psyco.sourceforge.net states:

High-level languages need not be slower than low-level ones.

Why use need not instead of do not need? What does it mean? Also, why no to before be?

also consider Brevity in the artful construction of language — New Alexandria, Sep 04 '13 at 13:27
This is subjuncitve mood. You can read this: https://web.cn.edu/kwheeler/grammar_subjunctive.html — martinkunev, Jul 09 '15 at 11:56
@martinkunev That is incorrect. Those constructions are different (and some would say shouldn't be called 'subjunctive' anyway). Read Cerberus's correct explanation. — Edwin Ashworth, Dec 09 '15 at 16:24
@EdwinAshworth What reason do you have to believe that this is not subjunctive mood? — martinkunev, Dec 09 '15 at 22:19
As Cerberus says, it's a usage of the modal 'need' (followed by the infinitive 'be'). 'You need not be present.' Compare 'You need not go.' / 'You must not be present.' You're confusing this with old-fashioned usages such as 'I insist that he be replaced.' (= 'I insist that he should / must be replaced.') — Edwin Ashworth, Dec 09 '15 at 23:34

Cerberus - Reinstate Monica · Accepted Answer · 2019-06-26T11:54:28.747

79

There are two verbs need, which mean the same thing but use different constructions:

1.

He need not be concerned.

Need I be concerned?

This need is sometimes called a modal verb (although others find this term inconsistent): it always requires an infinitive without to; it doesn't have do-support in questions and negative sentences; and the third person singular (he/she/it) doesn't have -s. This is the need in your example. It is of the same type as must, will, shall, can, may, help, and probably a few uncommon cases.

Modal need is slightly old fashioned. Except in negative sentences and questions, it is less common in modern writing, except perhaps in certain fixed expressions (though the need in if need be is a noun).

2.

He doesn't need to call her.

Do I need to call him?

She needs to call him.

You need him.

This is the more common need, a regular verb (no 'modal'). If it is used with another verb, the infinitive with to is used. It always has do-support. It can be used without another verb, with a direct object (you need him).

edited Jun 26 '19 at 11:54

answered Jun 10 '11 at 17:34

Cerberus - Reinstate Monica

61,585

1

Blast, you beat me to it. The Wiktionary entry for need has some handy usage notes that explain a few more forms of the word. – Jun 10 '11 at 17:37
@Rhodri: Hah, you lo—I mean, my apologies! – Cerberus - Reinstate Monica Jun 10 '11 at 17:40
11

+1 It doesn't seem that old-fashioned in the negative. Google Ngrams shows "need not" is still used much more often than either "needs not" and "does not need to". For the regular verb, you can see from the Ngram that "does not need to" is slowly replacing "needs not". – Peter Shor Jun 10 '11 at 18:40
4

@Peter Shor: Need is also a noun. With that ngram, you have no way of excluding things like "there is a need not to generalize". – Kosmonaut Jun 10 '11 at 18:48
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@Kosmonaut: I checked a sample, and the vast majority indeed seem to be need being used as a modal verb. – Peter Shor Jun 10 '11 at 18:51
1

@Peter Shor: If you have to browse through results to conclude that it seems to be used that way, then is the graph really worth anything? – Kosmonaut Jun 10 '11 at 18:58
4

If you put a "He" (capitalized so it goes at the beginning of a sentence) in the Ngram you get nearly the same results. I don't see how there could be any false positives in this set. – Peter Shor Nov 24 '12 at 18:18
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Great, now I need no longer have a bad conscience when writing phrases like "does not and need not compute ...." ;) – DaveBall aka user750378 May 31 '13 at 18:11
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Historical note: "need not" replaced "tharf not" during Middle English. The verb tharf was also a modal used only in the negative, and is cognate with the German modal verb dürfen, meaning must. – Peter Shor Oct 23 '13 at 15:02
1

@PeterShor: Damn, look what you did, you made me wander the depths of the OED and the WNT reading about all the cognates of tharf, and dare. Dare is apparently not related to tharf but was partly influenced by it. I always thought Dutch durven and English dare were cognates, but no, even despite past forms dorst and durst, respectively. – Cerberus - Reinstate Monica Oct 23 '13 at 16:41
1

There's a BrE and AmE difference, I think. Modal need or dare are more common in BrE than AmE. In BrE, it is common in negatives and interrogatives - and here we have an instance of the negative. – Peter Jun 27 '14 at 04:19
Can we use another modal with "need to", " what else can we need to reach our goal?" – Özgür Dec 24 '15 at 08:47
@Özgür: In general, you can use modal verbs with non-modal need (so that is need to), but in this example it doesn't sound right. I would just leave out can there. – Cerberus - Reinstate Monica Dec 24 '15 at 12:39
@PeterShor, German dürfen means to be allowed to (which in English is often negated as must not). – Carsten S Jun 04 '17 at 09:36
Note: the need in ‘if need(s) be’ is the noun, not the verb, so that doesn’t really fit in here. – Janus Bahs Jacquet Jan 18 '18 at 17:30
@JanusBahsJacquet: Ah, so be is a subjunctive? I'll remove the example. – Cerberus - Reinstate Monica Jan 18 '18 at 18:00
Exactly—there’s even a question about it. – Janus Bahs Jacquet Jan 18 '18 at 18:01
@JanusBahsJacquet: OK. Done. – Cerberus - Reinstate Monica Jan 18 '18 at 18:02
Is there a "Why need ...?" question? – Minh Nghĩa May 23 '20 at 21:22
I thought the regular verb was with s: "He doesn't needs to call he" – Ed_ Jul 10 '20 at 04:02
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@WeaponX: No, there are several mistakes in that sentence. – Cerberus - Reinstate Monica Jul 10 '20 at 13:02

Why use "need not" instead of "do not need to"?

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