I have seen posts on this forum about how She is coming back next Wednesday. shouldn't have the preposition on before next Wednesday. What I want to know is whether anyone here can help provide the rationale behind this grammar rule? I would like to teach my ESL students in our next class about not having to use on before all of this Wednesday, that Wednesday, every Wednesday, last Wednesday etc., and I'd like to provide them an explanation instead of asking them to memorize it. Any help will be appreciated.


1 Answer 1


It is a reasonable desire to find the rationale behind a grammatical rule.
It's what linguists want to do. It's what teachers and students would like to know.

Unfortunately, there are problems. One is that many rules don't have a rationale. They just are. Also, they are very rarely stated specifically. Even when they are, they're quite often wrong.

In this specific case, there can't be a hard rule, because dropping on with these phrases is an optional phenomenon. That is, the speaker may do it, or may not, at their sole discretion, depending on how they're feeling at the moment. Nobody can tell them whether to use it or not.

It is always allowed to use on with dates. As noted, determiners like next, last, this, that, some, every can precede the dates after on, and the on may be omitted. This is also true of any noun phrase that refers to a specific date:

  • He returned home (on) the same day she left.
  • I'm supposed to meet him (on) some day next month.

But it doesn't work with indefinite noun phrases denoting dates:

  • I like to run a on day like this.
  • *I like to run a day like this. (asterisk means ungrammatical)

As for the rationale, it's like a lot of deletions of small words in English.
Complementizer that, infinitive to, wh+be in Whiz-deletion, Conversational deletion, and so on. These are all meaningless words that guide the listener to the structures. As such, they are predictable.

When they're talking fast, with somebody they know well, people tend to leave things out. Every preposition in English is an unstressed syllable. English is a stress-timed language, in which unstressed syllables are reduced and jammed into the time between stressed syllables. So English speakers tend to delete predictable, unnecessary, unstressed syllables. A lot of these are prepositions. That's all, really.

  • This answer asserts that "on next Monday" is correct idiomatic standard English. Other answers and a reference contradict this. I agree there are time constructions in which "on" is optional, but is this one of them?
    – David K
    Commented Mar 15, 2020 at 3:27
  • It occurs to me you might think the other answers and the reference are all wrong. Which they might be. But I don't remember hearing or reading "on next Monday" in American or British English (though I think I recall hearing quaint expressions such as "on Monday next").
    – David K
    Commented Mar 15, 2020 at 3:37
  • She's coming back on next Monday, not next Tuesday. I express no opinion of the reference or other answers. The point is that individual use of optional rules varies widely, to the point where one simply cannot say that any such sentence is or is not "correct idiomatic standard English", even if that phrase were not a contradiction in terms. Optional rules are optional, and just about every rule is optional under some situations. Commented Mar 15, 2020 at 16:33
  • The word "on" still seems out of place in that example. The world won't come to an end due to a stray preposition like that, and the main purpose of language, which is communication, is satisfied. In that sense spelling, punctuation, and so forth also are optional up to the point where communication fails. It still seems useful to me to recommend to ESL students that they say, "She's coming back next Monday, not next Tuesday."
    – David K
    Commented Mar 15, 2020 at 16:48
  • Spelling and punctuation are optional in any case; they're not part of language or grammar. Orthography (written language) is technology and is no more relevant to sentence construction than are manual auto transmissions. Commented Mar 15, 2020 at 17:08

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