Requirement 1: Ideas must be expressed in the correct hierarchy of value.

‘Hierarchy of value’ refers to the importance of related ideas.

When we speak of two related ideas, what is their relative importance to each other? Are they equally important? Or is one idea more important than the other? And if so, how much more important?

Coordinate Ideas vs. Subordinate Ideas

Coordinate ideas

Ideas that are equally important are called ‘coordinate,’ from [co], meaning equal or together, and [ordinate], meaning order and rank. As described in models 5, 6 and 7 above, coordinate ideas in a sentence are connected using a semicolon or a coordinating conjunction, of which there are only six: and, but, or, nor, for, and yet.

Subordinate ideas

Ideas that carry unequal importance or value are called ‘subordinate’ and ‘main’ (though we refer to them simply as ’subordinate’). As defined in models 6 and 7 above, subordinate ideas in a sentence are connected using subordinating conjunctions and adverbial conjunctions.

So according to Requirement 1, if the ideas are coordinate, the sentence must express them using a coordinate structure, whereas if they are subordinate, the sentence must express them using a subordinate/main structure.

Hierarchy of Value – Case Study

Consider the following two related ideas about John. Keep in mind that in most contexts, Idea 1 would be much more important than Idea 2.

Idea 1: John is extremely sick.
Idea 2: John is 45 years old.

Keep in mind that in most contexts, these ideas are subordinate (Idea 1 > Idea 2). If we want to express them in a sentence, what are the options?

1. John is 45 years old and extremely sick.

2. John, who is 45 years old, is extremely sick.

3. John, who is extremely sick, is 45 years old.

4. John is 45 years old; moreover, he is extremely sick.

5. John is an extremely sick 45-year-old.

6. Extremely sick, John is 45 years old.

Although all of these are grammatically correct, only one meets Requirement 1.

1. John is 45 years old and extremely sick. Model 5: “and,” a coordinating conjunction, incorrectly suggests that the two ideas are equally important.

2. John, who is 45 years old, is extremely sick. Model 2: the less important idea is in a dependent clause, the more important idea in an independent clause.

3. John, who is extremely sick, is 45 years old. Model 2: the less important idea is in an independent clause, the more important idea in a dependent clause.

4. John is 45 years old; moreover, he is extremely sick. Model 6: “moreover,” an adverbial conjunction, incorrectly indicates that the two ideas are of near-equal importance.

5. John is an extremely sick 45-year-old. Model 1: the more important idea is in a phrase, the less important idea is a clause.

6. Extremely sick, John is 45 years old. Model 1: the more important idea is in an phrase, the less important idea is in a clause.

Logically, John’s illness is (in most contexts) more important than his age. By placing the more important idea in the more important part of the sentence, the writer makes the logic of the ideas in harmony with the way they are expressed.

This aids both the writer and the reader: the writer, because it guides his selection of the best sentence structure, and the reader, because it helps him more easily grasp the sentence’s ideas.