Politicians take advantage of listeners’ assumptions about what words mean and distort the truth without actually lying, University of Pennsylvania communication professor Kathleen Jamieson said at the University Law School on Wednesday.

“The facts that are relevant in a political piece of discourse are those that are needed by the reasonable person to draw the appropriate inference,” she said. “We are omitting factual information, hence being deceptive, if a reasonable person draws an inappropriate inference from the communication.”

Jamieson said she has done studies on “issue ads” that ask the audience to call a candidate on a certain issue but do not tell viewers which way to vote.

“We’ve asked people a half-hour afterward what the ad told them to do, and they said, vote against the candidate,” Jamieson said.

The Annenberg School for Communication dean delivered her lecture as part of the Kellar Distinguished Visitors Program.

Jamieson said political candidates regularly define common terms in unusual ways to confuse the public without lying, and she said the press often fails to clarify the confusion.

A classic example, Jamieson said, occurred when presidential candidates Al Gore and Bill Bradley debated in Iowa during the 2000 presidential primaries.

Jamieson showed a videotape of the debate in which Gore accused Bradley of voting against aid for Iowa farmers affected by flooding, and Bradley responded that the question was flawed because it focused on the past and Bradley wanted to talk about what he would do for farmers in the future.

“The problem underlying political debate can be digested in the Bradley/Gore exchange,” Jamieson said.

First, she said, Gore misrepresented Bradley’s vote on the aid plan. Bradley had supported an aid package, for which extra money was proposed, but he opposed the extra money because he believed it would only benefit large farms. In the end he nonetheless voted for the extra money, as did Gore, she said.

The press then covered the story tactically, she said, reporting Bradley’s failure to respond as an indication to voters that Gore’s statement was true.

Only later, once Gore had already won the primaries, did the media report on whether Gore’s claims against Bradley were true, Jamieson said.

“The press has the bizarre habit of penalizing people about three months after they’ve committed the crime,” she said.

Another example of poor media coverage came after the “fuzzy math” tax debate between Gore and George W. Bush, Jamieson said, when the two candidates did not respond directly to each other’s claims and Newsweek reported the truth was somewhere between the two candidates’ positions.

“Consensual understanding does exist on this issue,” she said, “but it isn’t arrived at by a split-the-difference relativism.”

The danger of candidates not directly responding to each other’s arguments is that voters might “disengage” from politics, assuming both candidates must be lying or the truth cannot be known, Jamieson said, or each voter might decide his or her preferred candidate must be the truthful one.

Jamieson said the media should hold candidates accountable for using words consistently and clarify when candidates use “pseudo-rebuttals” rather than directly responding to opponents’ arguments.