Daniel Okrent's "The Privileges of Opinion, the Obligations of Fact" editorial in the New York Times should be required reading for anyone who reads opinion writing (and especially those who chose to quote from it to support their own opinions.

But who is to say what is factually accurate? Or whether a quotation is misrepresented? Or whether facts are used or misused in such a fashion as to render a columnist's opinion unfair? Or even whether fairness has anything to do with opinion in the first place? Can you imagine one of the Sunday morning television screamfests instituting a corrections policy?

In the consciously cynical words of a retired Times editor, speaking for all the hard-news types who find most commentary to be frippery, "How can you expect fairness from columnists when they make up all that stuff anyway?"

Of course they don't make the stuff up (at least the good ones don't). But many do use their material in ways that veer sharply from conventional journalistic practice. The opinion writer chooses which facts to present, and which to withhold. He can paint individuals he likes as paragons, and those he disdains as scoundrels. The more scurrilous practitioners rely on indirection and innuendo, nestling together in a bed of lush sophistry. I sometimes think opinion columns ought to carry a warning: "The following is solely the opinion of the author, supported by data I alone have chosen to include. Live with it." Opinion is inherently unfair.