I was asked what the difference between need and necessity was by a non native speaker. It was in the context of the name of an article to do with global warming, i.e "The need/necessity for….". I was completely stumped and googling it only produced speculative answers.
In my mind a necessity is an absolute requirement, for example food and water is a necessity for survival. I would have said that a need is a requirement but maybe not an absolute one. For example, there is a need for an umbrella when walking outside in the rain.
Could you please give a definitive answer, if there is one?
EDIT – Attempting to address Edwin Ashworth's need for signs of research.
The Oxford English Dictionary defines need and necessity as follows
Need – Necessity, requirement.
Necessity – Constraint or determination by some external force; an instance of this.
In Fleischer's 1804 book "English Synonymous Or the Difference Between Words Esteemed Synonymous in the English Language: Useful to All who Would Either Write and Speak with Propriety and Elegance", need and necessity are given by
Need and necessity relates less to the situation of life than the other three words [in the context of poverty, indigence and want]; but more to the relief we expect or the remedy we seek, with this difference between the two that need seems less pressing than necessity.
although this is both contextual and dated. I am struggling to find other reliable sources, hence my post on this website.
Best Answer
Several reference works have attempted to draw distinctions between need and necessity since Fleisher did so in 1804. From George Crabb, English Synonymes Explained, in Alphabetical Order (1816):
From George Graham & Henry Reed, English Synonymes Classified and Explained (1847):
From Charles Smith, Synonyms Discriminated: A Dictionary of Synonymous Words in the English Language (1910):
From James Fernald, English Synonyms, Antonyms, and Prepositions, thirty-first edition (1914):
From Webster's Dictionary of Synonyms (1942):
The updated version of this dictionary, Merriam-Webster's Dictionary of Synonyms (1984) uses different examples to illustrate the distinctions it makes between need and necessity, but the wording of the distinctions themselves is virtually unchanged from the 1942 edition.
From Bergen Evans & Cornelia Evans, A Dictionary of Contemporary American Usage (1957):
From William Morris & Mary Morris, Harper Dictionary of Contemporary Usage, second edition (1985):
An Ngram chart of "no necessity for" (red line) versus "no necessity of" (blue line) versus "no necessity to" (green line) for the period 1700–2019 suggests that "no necessity to" has been in idiomatic English use for centuries:
But the key point in Morris & Morris's treatment of the entry for necessity/need is the assertion that "necessity and need are synonymous." Coming after the numerous efforts to distinguish the two terms from one another, this matter-of-fact statement that the two words mean the same thing is a bit startling—but I think it is true for most English speakers.
Some nuanced speakers and writers seem clearly aware of a greater intensity, longevity, or motivating force of necessity in comparison with need. Others are more fitful in their awareness of any distinction in sense or overtone between the two words—or simply use them interchangeably.
In trying to distinguish between close synonyms, you should bear in mind that most people who grow up speaking a language acquire their understanding of what the words mean more or less osmotically—especially in the case of common words that they are likely to have encountered (and used themselves) from a fairly early age. They don't start out by consulting a dictionary and trying to apply the meanings they find there to the situation they want to talk about. For this reason, it is difficult to estimate with any confidence the extent to which real-world usage ever abided by the definitions and distinctions that lexicographers and usage experts recorded and prescribed through the years.