Recently I ran across the sentence:
"Just why the law prescribed thirty-nine lashes instead of forty or forty-one and so on, must needs remain unanswered."
How did a plural verb like "needs" wind up as an adverb? Is it alone in this phenomenon, or are there other examples that appear to be an odd misplacement of a second verb, but are actually adverbs as well?
Needs is an old-fashioned or even archaic adverb in modern English. It comes from the noun need and the Germanic masculine/neuter genitive ending -s, which at some point in time came to be used in older English and other Germanic languages to form adverbs. From the Oxford English Dictionary:
In once, twice, thrice, hence, since, etc., the suffix is written differently. In against, alongst, amongst, amidst, and the dialectal onst (see once), the original -es, -s has become -st.
This suffix is still frequent and semi-productive with other stems in Dutch: onverwachts "unexpectedly", daags na "a day after", etc. I believe German has similar examples. English always, sideways etc. contain the same suffix.
In Old English or earlier, before the emergence of the adverbial suffix -s, there existed several masculine and neuter words in the genitive case—which ended on -(e)s—that were used adverbially: dæges "by day", nédes "needs", þances "voluntarily". By analogy, this masculine/neuter genitive ending was extended to make adverbs out of feminine nouns as well, as in nihtes "by night". From there it became a general adverbial suffix. (Examples were taken from the OED.)
I'm not so sure it "wound up" an adverb/adjective. Chaucer wrote A man must needs love mauger his head (where I'm guessing mauger relates to French malgré = in spite of)
Thanks to @pavium for this link - which deserves more upvotes than my answer!
The usage is generally archaic/formal/academic. It probably survives partly because it echoes the equally archaic needs must [when the Devil drives].
It's not a "plural verb" (nor "second person singular verb", nor "plural noun"). I think it's always been an adverb meaning "necessarily". I'm not aware of any other words that happen to be both noun and verb and have an [archaic] adverbial form that's the same apart from ending is 's', but even if there were, I doubt you could call it a meaningfully productive 'pattern'.
Semantically, needs functions as an intensifier to the preceding must. It doesn't really need to be present - it's just adding emphasis, with perhaps a touch of gravitas from the archaic overtones.
This question was discussed here:
While the reference classifies needs as an adverb, I think it owes more to [the imagined requirements of] conjugation than number for the 's' at the end. (as in 'I need', 'He needs', etc)
It's more likely a writer affecting a older style of writing, in line with the subject of corporal punishment.
It may be helpful to read the phrase must needs as must, of necessity.
Why does this make sense? As mentioned by others here, the -s on needs is an artifact from the Germanic genitive suffix -es, used most often to show possession. In modern German, the genitive case can usually be translated to English using the preposition of.
For instance, in das Kleid meiner Schwester, the suffix -er has been added in place of a preposition in order to make clear the owner of the dress (meiner is genitive, cp. the alternative dative von meiner). In English, the phrase could read my sister's dress, or, more aptly, the dress of my sister. The analogy to "must needs" and "must, of necessity" is immediate.
It is used by Tyrion Lannister in the first Game of Thrones book. Here it is simply intended to be a synonym for "has to". However the structure is abandoned by George RR Martin in subsequent books.
"Must needs" occurs a number of times in Shakespeare. I used to think it was Shakespeare twisting words around for effect. Now I see he's using a common phrase of his day for emphasis and rhythm.
For example, Puck in Midsummer Nights Dream: III,2
"Then will two at once woo one; That must needs be sport alone;"
"Must needs" is an archaic phrase used as an adverb, meaning 'must necessarily". It is similar to "have to" or "has to" : He must needs do it. = He has to do it.
