In this second group the words following “or” are explanatory of the word preceding “or.” One anesthetic with two names is spoken of. The comma notifies the reader that the relation in the second group is not the relation existing in the first,—that is, the apparent relation in the second group is not the real relation.

Many writers would put “or nitrous oxide” in parentheses. The meaning would be unmistakable; but the punctuation is not commendable, as we have already seen. “Nitrous oxide,” without the “or,” could properly be enclosed in parentheses.

AFTERTHOUGHT

There is a very common use of the comma before “or” which reveals a nice meaning of language. The punctuation grows out of a writer’s desire to modify a meaning which he has expressed, frequently, in a word that is too strong. He follows this word with another in the or relation to the too-strong word. In order to show that the real or relation, as discussed under No. 17, does not exist between the two words, and that the relation of explanation (slightly parenthetical), as discussed under No. 11, is the real relation, he applies the principle of disjunction, exhibited in another form in the discussion of Sentence 1, and uses the comma.

In our first illustrative sentence (No. 17A) the fact that a word of milder, not coördinate, meaning is to follow “or,” is indicated both by the group of words (I should say) and by the modifier (even) preceding the word in the or relation to “independent.” The comma before “or” would be required in the absence of either or both of these modifiers, as shown in Nos. 17A-1 and 17A-2. It is especially needed in No. 17A-2 to distinguish the real from the apparent meaning:

17A. This capital does not make him independent, or, I should say, even aspiring.

17A-1. This capital does not make him independent, or even aspiring.

17A-2. This capital does not make him independent, or aspiring.

The word or words used in modification of an idea expressed either too strongly or too weakly, are aptly called an “afterthought”; and such word or words themselves suggest the parenthetical nature of the added language.

Our next illustrative sentence shows the use of a word that is too weak; and therefore the sense requires a stronger word. The sentence is particularly interesting because it is a type of sentences that are almost invariably punctuated wrong, even by our best writers:

18. It is a matter of whim, or, worse, of economy.