Only a handful of rules of English composition are cast in stone. Most of the supposed rules are cast in tapioca. The stoniest of all the stone-cast maxims is this one: Subject and predicate must agree in number. When the subject is clearly singular or plural, the rule works splendidly -- but what if the subject is "none"?
Here we plunge into anarchy. You may stay awake for hours, reading the counsel of such sages as Fowler, Partridge, White, Garner, Bremner, William & Mary Morris, and the editors of Webster's Dictionary of English Usage, and you will come up with this profound conclusion: We should use "none is" when "none is" feels right, and "none are" when "none are" feels right. All clear?
Two years ago, in a case against the Virginia Military Institute, Supreme Court Justice John Paul Stevens looked at the litigants who had invoked the court's jurisdiction: "In this case, none of the parties has a present stake in the outcome." None has.
At about the same time, The New York Times was reporting on some passing adversities of commentator Rush Limbaugh: "None of the 600 stations that carry the program have dropped it." None have.
The Times' Manual of Style & Usage directs its adherents to treat none as plural "except when emphasizing the idea of 'not one' or 'no one.'" The U.S. News Stylebook reminds us that "none" always takes a singular verb when it precedes a prepositional phrase, e.g., "None of the work is finished." The stylebook of the Los Angeles Times gives the topic a brush-off.
In my own view, the choice of a singular or plural verb with "none" depends primarily upon the sense of what we're trying to say. And the sense of the thing will whisper in our ears. In the absence of clear-cut rules, we have to go with what sounds right. This is not anarchy. This is judgment aged by experience.
Example: Not long ago, The New York Times observed editorially that South Korea, Japan, China and Russia have an immediate stake in relaxing tensions with North Korea: "None of these countries are prepared to give up on diplomacy." My ear would have suggested, "None of these countries is prepared ..."