Merriam-Webster’s Dictionary of English Usage (MWDEU) is a thoroughly researched and witty compendium on usage. Unlike ‘Merriam-Webster’s Collegiate Dictionary,’ which has only occasional usage notes, MWDEU presents 2,300 detailed entries. Each MWDEU entry, typically, comprises a history of its usage, with examples cited from classic and contemporary texts, and concludes with a recommendation — not a prescription — from the editorial board. As an example of the MWDEU editors’ comprehensive review, let’s take a look at the “less/fewer” distinction.
The authoritative usage reference in academia, “The Chicago Manual of Style, fifteenth edition,” prescribes a simple-to-follow rule: “Reserve ‘less’ for mass nouns, or amounts–for example, less salt, dirt, water. Reserve ‘fewer’ for countable things–fewer people, calories, grocery items, suggestions. One easy guideline is to use ‘less’ with singular nouns and ‘fewer’ with plural nouns” (p. 221). This simple prescription, however, is oversimplified. It is inaccurate as MWDEU notes below.
MWDEU begins its detailed entry (pp. 592-94) by commenting on the above rule: “This rule is simple enough and easy enough to follow. It has only one fault — it is not accurate for all usage…. ‘Less’ refers to quantity or amount among things that are measured and to number among things that are counted.
“As far as we have been able to discover, the received rule originated in 1770 as a comment on ‘less’: ‘This Word is most commonly used in speaking of a Number; where I should think Fewer would do better. “No Fewer than a Hundred” appears to me, not only more elegant than “No less than a Hundred,” but more strictly proper–Baker 1770.