Ben Yagoda in the Chronicle of Higher Education:
Not long ago, I took part in a panel discussion at the Free Library of Philadelphia. My fellow panelists were two linguists and a lexicographer. Anyone who knows any linguists and lexicographers will be unsurprised to hear that their position on usage was descriptive rather than prescriptive: They were interested in charting and interpreting recent and historical changes in the way English is written and spoken, not interested in labeling those changes as “mistakes,” and even less interested in decrying such so-called errors as evidence of a decline in American civilization.
At the end of our conversation, there was time for questions from the sizable audience. The first questioner stood up and said (I paraphrase), “It always drives me crazy when people use 'impact' as a verb. How can we abolish that?”
The panelists hemmed and hawed, murmuring sweet nothings like “the language changes” and “functional shifting.”