On commas

A student, writing about punctuation, complains that 'The comma is a particular pain, as there appears to be no definitive rules governing its placement. For example, do you always punctuate adverbials (as one writing guide suggests) or is it a matter of preference (as another suggests)? Is a comma required after and, as in the sentence, Jeremy glanced at the clock and abruptly closing his book leapt up from the sofa, or does it come before and?' And he asks if I can recommend a book...

The reason punctuation presents such a problem is because it is trying to do two very different jobs - one phonetic, the other grammatical. On the one hand, people are using it as a guide to how the rhythm of a sentence should sound (if they were to read it aloud); on the other hand, they are using it as a guide to the grammatical structure of a sentence - to what it means. On top of this, there are graphaesthetic considerations of elegance - wanting to avoid too many marks in a sentence, for example.

The most natural rhythm of the sentence cited breaks it into three parts, and if commas are used to represent the pauses it would be written like this:

(1) Jeremy glanced at the clock, and abruptly closing his book, leapt up from the sofa.

If you decide to use commas to show the grammar of the sentence, it comes out like this:

(2) Jeremy glanced at the clock, and, abruptly closing his book, leapt up from the sofa.

But the sequence of three commas looks too cluttered for some writers, so they would simplify to:

(3) Jeremy glanced at the clock and, abruptly closing his book, leapt up from the sofa.

This privileges grammar but goes clean against rhythm, for no-one would ever say 'Jeremy glanced at the clock and' as a single rhythmical unit.

There are other ways of avoiding the comma repetitiveness of (2), as in (4):

(4a) Jeremy glanced at the clock, and (abruptly closing his book) leapt up from the sofa.
(4b) Jeremy glanced at the clock, and - abruptly closing his book - leapt up from the sofa.

But the parenthesis and dash have visual connotations that are not present with the comma, so these solutions are not always congenial.

There seem to be two trends in English: some people are over-punctuators (as in (2) above) and some are under-punctuators, as in the following:

(5) Jeremy glanced at the clock and abruptly closing his book leapt up from the sofa.

Under-punctuation can lead to miscues - that is, you think the sentence is going in a particular direction and start to read it that way, then you realize that it doesn't, and have to go back. The miscue in (5) is due to the fact that the word and can link two words in a phrase (as in (6)) or two clauses (as above).

(6) Jeremy glanced at the clock and the picture...

A comma after clock avoids the miscue.

When people write, they sometimes follow the phonetic principle and sometimes the grammatical. A lot depends on other factors, such as the length of the clauses and the rhythmical complexity of the words they contain. The longer that clause abruptly closing his book gets, the more likely it will be given surrounding commas:

(7) Jeremy glanced at the clock and, abruptly closing the book on mathematics that he had been reading casually for two days, leapt up from the sofa.

Another factor is publishing house preference. For example, usage varies between publishers in the use of the so-called 'serial' comma:

(8) A tall, dark (,) and handsome man stood in the corner.

Some publishers insist on including it; others insist on omitting it.

One thing is certain: it is not possible to explain good authorial usage by prescriptively insisting on a single principle and making people feel guilty when they instinctively feel the need to depart from it. That is unfortunately what popular books on punctuation generally try to do - which is why you have to be very cautious when you read them. But Pam Peters has some well-judged observations on punctuation in her Cambridge Guide to English Usage.