that is.
Conventional wisdom once held that if this phrase begins a sentence, the result is a sentence fragment. But good writers unimpeachably use the phrase in this way, in place of “in other words” — e.g.:
o “While adopting certain teaching techniques, we are more interested in communication than in composition. That is, with due respect to Shakespeare and others, we want our girls to communicate freely with the live world around them rather than plunge into musty old books.” Vladimir Nabokov, Lolita 179 (1955; repr. 1982).
o “But the base and, I believe, the country want someone in the White House who doesn’t sound like another George Bush. That is, they want someone who doesn’t suffer from an infallibility complex, who can admit mistakes and learn from them.” Paul Krugman, “Wrong Is Right,” N.Y. Times, 19 Feb. 2007, at A15.
Because of the close relationship between what follows “that is” and what comes before, a semicolon or an em-dash often substitutes for a period before “that is” — e.g.:
o “Definitions, contrary to popular opinion, tell us nothing about things. They only describe people’s linguistic habits; that is, they tell us what noises people make under what conditions.” S.I. Hayakawa, Language in Thought and Action 171 (1949).
o “Wages and salaries serve the same economic purposes as other prices — that is, they guide the utilization of scarce resources which have alternative uses.” Thomas Sowell, Basic Economics 144 (rev. ed. 2004).
For information about the Language-Change Index click here.
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Quotation of the Day: “Growth in the art of writing or speaking may be defined simply as a process of becoming increasingly ‘reader-minded’ — able, that is, to test one’s own expression for its actual clearness and force to those he intends it for.” Sterling Andrus Leonard, English Composition as a Social Problem 14 (1917).
