In an age defined by disinformation, it has become almost a cliche to talk about “post-truth politics.” But while truth has been the media's foremost concern in the era of "fake news," there has been surprisingly little reflection on what it actually means in the first place. We're exhorted to defend it from authoritarian leaders and conspiracy theorists alike, yet we seldom consider what precisely it is that we’re defending. But Sophia Rosenfeld, a historian at the University of Pennsylvania, certainly has. 
 
“Truth is definitely a slippery idea,” she tells New Lines Magazine's Faisal Al Yafai. “The way truth works, especially in democratic settings, is that we don't authorize any one person, or one institution, or even one method, say, as the way to know something. That is wonderful in certain ways. But of course, it also makes knowing anything very messy.”
 
But while the truth may never have been as certain as many like to imagine, today’s degree of polarization nevertheless poses a new and dire challenge.“To have a good debate, we have to first agree that there's a problem,” says Rosenfeld. “If we can't even agree on something like the unemployment rate, democracy starts to fall apart.”
 
“The law doesn't help us much here,” she adds. “The technology doesn't help us much here. We're catching up with a phenomenon that we didn't know we were unleashing when we did."
 
Produced by Joshua Martin