Learn English – Are there rules about using “that” to join two clauses

1.) "Nobody move and nobody get hurt."

When this sentence is shouted out by bank robbers at the customers inside a bank, then the customers know pretty darn well what is being communicated: If nobody moves, then nobody gets hurt. That is, if you are a bank customer and you don't want to get hurt by the robbers, well, one way to not get hurt is to not move.

In the other thread, the OP wanted to know if a sentence in a wikipedia page was grammatical: http://en.wikipedia.org/wiki/Nobody_Move,_Nobody_Get_Hurt

Nobody Move, Nobody Get Hurt is a cliche from hold-up movies, and may refer to: . . .

And the OP was also wondering about the version:

• 2.) "Nobody move and nobody gets hurt."

Basically, the two versions really only differ in the clause type of the 2nd clause in the coordination:

• 1.) "Nobody move and nobody get hurt."

• 2.) "Nobody move and nobody gets hurt."

Both versions use an imperative clause as the 1st coordinate. The difference is that the #1 version uses an imperative clause for the 2nd coordinate, while #2 uses a declarative clause for its 2nd coordinate. But both #1 and #2 versions basically have the same interpretation: If you don't move, then you don't get hurt. The sentences are interpreted as if they were a conditional construction. The directive force of "Don't move!" is retained in both versions.

In any case, they most certainly do not have the meaning:

• 3.) "Nobody move or get hurt."

If bank robbers yelled "Nobody move or get hurt!", then the bank customers might glance at each other, wondering what in the world was going on. (Eventually, the customers might figure out that the bank was getting robbed by EFL speakers.)

Often, there are some EFL speakers (and pedants) that assume that the coordinator "AND" can only be involved in symmetric constructions: constructions where the order of the two coordinates can be reversed with no change in meaning of the sentence. E.g.

• A.1 "Tom likes [to run cross-country] and [to swim across the lake]."

• A.2 "Tom likes [to swim across the lake] and [to run cross-country]."

In those above two versions, they both have the same meaning.

But their understanding about the coordinator "AND" is wrong.

Because "AND" is also commonly involved in asymmetric constructions: constructions where the two coordinates resist having their order be reversed, or when reversed, cause the sentence to have a different meaning. Here below are some examples of asymmetric constructions.

Temporal sequence: "X and Y" implicates "X and then Y"

• B.1 "He got up and had breakfast."

• B.2 "He had breakfast and got up."

Here, there is a temporal sequence of the events. In this case, for #B1, that he got up and then had breakfast, while for #B2 that he had breakfast in bed before getting up out of bed.

Consequence: "X and Y" implicates "X and therefore Y"

• C. "I fell off the ladder and broke my leg."

You can infer that I broke my leg as a result of falling off the ladder. (Reversing the coordinates is not an acceptable alternate.)

Condition: "X and Y" implicates "if X then Y"

• D.1 "Do that again and you'll be fired."

This implicates that "if you do that again then you'll be fired". This example has an imperative clause and a declarative clause. The following example has two imperative clauses, (which is somewhat similar to the form of this thread's OP's example)

• D.2 "Join the Navy and see the world."

which has the meaning "that you'll see the world if you join the Navy".

Concession: "X and Y" implicates "despite X, Y"

• E. "You can eat as much of this as you like and not put on weight."

Temporal inclusion: "X and Y" implicates "X while Y"

• F. "Did he come in and I was still asleep?"

Formulaic frames: And there are expressions where the constructions of "X and Y" are sorta idiomatic or are idioms or are fixed or are partly fixed. Some examples are:

• "The coffee is nice and hot."

• "Try and not be so touchy."

• "Be sure and lock up."

• "The TV has gone and broken down."

• "They sat and talked about the wedding."

• "Be an angel and make me some coffee."

And there's also asymmetric constructions involving the coordinator "OR". For example,

Condition: "X or Y" implicates "if not X, then Y"

• "I'm leaving before the end or I'll miss my train."

• "I left early or I would have missed my train."

• "Hurry up or we'll be late."

• "Don't do that again or you'll be fired."

. . .

And so, hopefully you've gotten the picture. There are a lot of asymmetric constructions, and they are part of today's standard English. We native English speakers use them, easily and often.

Note that most of the examples and most of the info were borrowed from the 2002 reference grammar by Huddleston and Pullum et al., The Cambridge Grammar of the English Language (CGEL), pages 1299-1304.

EDITED for adding links:

Here's my post in the other thread that discusses the grammaticality of the two versions:

• https://english.stackexchange.com/a/155131/57102

Here's my post on imperative clauses with a 3rd person subject:

• https://english.stackexchange.com/a/137100/57102

Any expectation of a comma in the examples of the OP has very little to do with the subordinate clauses' restrictiveness, but rather, as the OP suggested, with an interruption of their natural flow. When leading a sentence with a subordinate clause, the comma does not force a "parenthetical / non-restrictive" interpretation. Simply, compare the meaning of two sentences:

• If you work hard, you get rewarded.
• You get rewarded if you work hard.

None of the embedded phrases in the examples were relative clauses, so the concern of imposing a non-restrictive interpretation is irrelevant. In every case, the embedding did put the interrupting phrases in a parenthetical position--even if they are considered "essential" to the meaning of the sentences.

The reference to section 6.32 of The Chicago Manual of Style 16th edition established a legitimate exception to a general rule of commas. If omitting an appropriate comma creates no ambiguity, omitting it becomes a matter of style opinion rather than grammar. Moreover, if we believe an appropriate comma introduces ambiguity, our best solution is to recast the sentence to remove ambiguity.

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Considering the options for each example:

1) This is the country where[,] if you work hard, you get rewarded. (relative clause)

The relative clause is where you get rewarded, and the comma is appropriate, because the embedded conditional phrase, if you work hard, interrupts the natural flow of the clause. The conflict between the locative where and the conditional if might be manageable enough, but many would be more comfortable with the extra comma. If the sentence had been written: This is the country where you get rewarded if you work hard, certainly no commas would be needed.

2) We need to talk because[,] if we don't, we will be in trouble. (adverbial clause)

The adverbial clause is because we will be in trouble, and the comma is appropriate, because the embedded conditional phrase, if we don't, interrupts the natural flow of the clause. With such minuscule conflict between because and if, there is very little risk of confusion in omitting the comma. If the sentence had been written: We need to talk because we will be in trouble if we don't, certainly no commas would be needed.

3) London is where[,] when I was young, I used to live. (noun clause)

The predicative is where I used to live, and the comma would be appropriate, because the embedded adverbial phrase, when I was young, interrupts the natural flow of the clause. The locative where and the temporal when are nearly irreconcilable and should probably be separated by a comma. If the sentence had been written: London is where I used to live when I was young, certainly no commas would be needed.

4) Give me a call if[,] when you are at the station, it rains. (adverbial clause)

The conditional clause is if it rains, and the comma is appropriate, because the embedded adverbial phrase, when you are at the station, interrupts the natural flow of the clause. The conditional if and the temporal when seem to be in deep conflict and would work better with a comma between them. If the sentence had been written: Give me a call if it rains when you are at the station, certainly no commas would be needed. The slight ambiguity could easily be eliminated by recasting the sentence to communicate the true intentions of the imperative.

5) It is useful when[,] if it rains, you have an umbrella. (awkward adverbial clause)

The awkward adverbial clause is when you have an umbrella, and the comma is appropriate, because the embedded conditional phrase, if it rains, interrupts the natural flow of the clause. This construction is awkward with or without the comma, but would probably be less confusing with the extra comma. If the sentence had been written: It is useful when you have an umbrella if it rains, certainly no commas would be needed. The overall awkwardness still suggest a need to recast the sentence.

6) She is the person who[,] if she is faced with difficulties, can handle them very well. (relative clause)

The relative clause is who can handle them very well, and the comma is appropriate, because the embedded conditional phrase, if she is faced with difficulties, interrupts the natural flow of the clause. The conflict between the relative who and the conditional if might be manageable without a comma, but many would find it less confusing to see the comma. If the sentence had been written: She is the person who can handle difficulties very well if she is faced with them, certainly no commas would be needed.

7) He said that[,] if all goes well, he will call. (noun clause)

The noun clause is that he will call, and the comma is appropriate, because the embedded conditional phrase, if all goes well, interrupts the natural flow of the clause. The conditional in the context of reported speech is the least awkward of the seven examples and fits the exception of The Chicago Manual of Style perfectly. If the sentence had been written: He said that he will call if all goes well, certainly no commas would be needed.

Conclusion:

The ultimate purpose of commas is clarity. Use one if it makes things more clear. Leave it out if it makes things less clear, and in my humble opinion: when in doubt, leave it out. Most importantly, recasting the way we put phrases together can eliminate most of our comma confusion.