Comma sutra

Punctuation isn't supposed to happen at random; it's supposed to help guide perplexed readers toward the clear light of True Meaning (if you missed the National Punctuation Day festivities on Monday, you can catch up here, thanks to the scholars at Language Hat). Three examples from one of our favorite dailies illustrate the perils of sticking commas between modifiers without first asking the modifiers what it is they're trying to modify.

For this purpose, we need to talk about the difference between coordinate and cumulative adjectives (we'll leave compounds for the first case of egregious overhyphenation of the semester). Coordinate adjectives, which are separated by commas, are of equal weight and apply equal force to their noun. To test whether two adjectives meet these conditions, and thus should be comma-ated, invert them:

Freedonia's feckless, arrogant policy.
Freedonia's arrogant, feckless policy.

or balance them on a conjunction:

Freedonia's policy is feckless and arrogant.

Cumulative adjectives pile on their meaning step by step and aren't separated by commas. They answer a series of "what" (or how, why, &c) questions:

A cold January morning.

What kind of morning? A January morning. What kind of January morning? A cold January morning.

Notice that the cumulative pair fails both the tests of the coordinate adjectives:

A cold January morning.
* A January cold morning.
* The morning was January and cold.
The January morning was cold.

You can infer from the last two that an attributive noun modifier can't coordinate with an adjective. Hold that thought, and let's go to the videotape:

Charlotte transit officials will unveil plans tonight for a long-discussed, $100 million station on West Trade Street that would serve Amtrak, commuter rail, buses, streetcars and taxis.

What sort of adjectives are "long-discussed" and "$100 million"? Test 'em:

* The $100 million long-discussed station.
* The station is $100 million and long discussed.
The long-discussed $100 million station. (What sort of station? $100 million. How has it been discussed? Longly!)
The long-discussed station would cost $100 million.

These, then, are cumulative modifiers and don't take a comma. Put them in the predicative position -- The station has been long discussed. The station would cost $100 million -- and, again, you'll see why they don't coordinate. Verdict: No comma.

Example #2 (from an edpage comment, and you probably don't want the details of this case):

This implies that a mostly white, Southern police force conspired to protect a black, petty burglar with a long police record in order to go after a young, white, wealthy doctor with no record!

A black petty burglar.
* A petty black burglar.
* A black and petty burglar.
(What kind of burglar? A petty burglar. What kind of petty burglar? You get the idea: No comma.)

Example #3:

North Carolina's lawmakers prepared to leave the capital Tuesday night after an overtime, seven-month session that left as many sweeping questions unanswered as it settled.

A seven-month overtime session. (hmm, can't rule it out)
* An overtime and seven-month session.
An overtime seven-month session. (How long did the session last? Seven months? What kind of seven-month session was it -- pretty normal? No, overtime.)

This one's closer to the bubble, but because it fails the conjunction test and passes the accumulative test, lose the comma.

True story. One of this paper's revered wordsmiths once proclaimed that when he'd been a writing teacher, he always taught that the fewer commas you had, the better your style was. That's typical magic-think, and we don't want writers to go away thinking that good writing is supernatural. It ain't. Good writing starts with basic principles of good construction. Hot water doesn't come out of the tap by magic. It comes out because somebody hooked the tap up correctly.