That, in fact, is the first thing to remember about commas: they cut, separate, detach, isolate. Their very name derives from a Greek verb, koptein, which means to cut, and the word comma originally signified a clause, what we know grammatically now as a group of words with a subject and verb, but which originally meant (and still does in other contexts) a distinct or separate section of a document or discussion.
So why all this grammatical minutiae? Because there is nothing minute about the results of misusing this ubiquitous mark of punctuation, results having little to do with grammatical etiquette and almost everything to do with saying exactly what we mean. Consider, for example, this headline that appeared online recently on CNN: Appeals court dismisses Gohmert case asking Pence to interfere in Electoral College vote count. The writer got it right, but many of us might have wondered whether there should have been a comma between case and asking: we might very well pause there a slight second in speaking the sentence, so don’t you put a comma where you breathe?
Punctuating by watching the breath, though many of us learned early in school to do that, is actually a sophisticated device that applies to what is called rhetorical punctuation, shaping the sections of a sentence into audible waves that will carry the reader over the ideas, smoothly or roughly as the content suggests. The term rhetorical means persuasive, and the art of persuasion, called rhetoric, is always working complementarily with logic, the two sometimes pulling together and sometimes apart. Persuasion has to do with the emotions, and logic has to do with thought, what we refer to sometimes as heart and mind. And although Pascal was certainly right in saying that we know the truth not only by reason but also by the heart, the two cannot contradict each other or we simply stand confused.
And so it is in writing. To have placed a comma between case and asking in the headline would have been to cut or separate the participial phrase from the noun it modifies. The noun case, or more fully Gohmert case, is the direct object of dismisses, and the nine words that follow comprise a participial phrase that defines the Gohmert case. That participial phrase, then, is an adjective that supplies information judged to be essential to the reader in understanding quickly (the very purpose of a headline) what the Gohmert case was about. Adjectives that attach essential, defining information in this way are not to be separated or cut away from the noun they so importantly modify, and so a comma should not be inserted between the two words. To yield here to the heart’s wish to sigh would only confuse the mind.
How? By placing a comma between case and asking, the writer would have been alerting the reader that the participial phrase was not intended to modify case, but rather appeals court: commas separate, and placing a comma after case would have been instructing us to look past the first noun referent and to keep looking until the next is found. And the result of that would have confused us, because the headline would then have meant that the appeals court dismissed the Gohmert case and then asked Pence to interfere in the Electoral College vote count—a menacing confusion of democracy indeed.
As ever seems to be the case, truth lies in the detail. Details, though, are little things, and we can often convince and persuade ourselves that something as minute as a comma (or that tiny, tiny pill the doctor just prescribed) can’t possibly do that much. But looked at the other way, we are trying to do something quite audacious when we write: we are trying to give form to that stupendous welter and whirl we call our experience, to catch that wind in words and show all it does to someone else. That’s quite a thing, and we need to know the details of grammar and logic to do it well.