WASHINGTON – It’s unprecedented, the experts say: The volume and audacity of distortion, deception and truth-stretching in this year’s presidential campaign has political fact-checkers busier than ever in their pursuit of the truth. But whose truth, precisely? And, in the context of a bitter campaign, does the actual truth – and the responsibility of a politician to tell it – really matter?

The question hangs over every modern campaign, and of course lying and truth-stretching have abounded in politics throughout U.S. history. But there are differences this time around. The convention speech last week by GOP vice-presidential nominee Paul Ryan may have brought the conversation into focus, but his carefully parsed words are hardly the only ones in the political arena that make people wonder if truth is becoming elastic.

“The partisans of the two parties might have a different attitude toward the truth,” said Lionel McPherson, a professor of ethics and political philosophy at Tufts University. “It’s possible one side doesn’t care – they think they can make those claims to their base with impunity, even if it’s obvious those claims are false or misleading.”