Mr Davis yesterday also urged students attending the University of Otago’s latest summer school to be "warriors for truth" in the face of lies and conspiracy theories.
He acknowledged the huge power of social media, and its ability to convince intelligent, well-meaning people of false-hoods, including that former US president Barak Obama was not a US citizen and a gold ring he wore was part of an Islamic conspiracy.
It was sometimes tempting to view some false claims "as a joke, as a cause for humour or a bit of fun".
However, he urged "taking responsibility for what information you consume" and what was passed on to others.
In his lecture on "Journalism Now", Mr Davis highlighted the dangers of misleading conspiracy theories which sometimes distracted from inconvenient truths, such as inadequate firearm controls which contributed to the Sandy Hook School massacre in Connecticut in the United States, in 2012 in which 26 people were killed, including teachers and many children.
A Texas-based conspiracy theorist had initially denied the killings had taken place, and his repeated claims meant some families whose children had been killed were also receiving abusive late night phone calls.
Mr Davis acknowledged the huge power of social media and the ease with which disinformation could be spread, potentially damaging not just individuals but democracy itself.
Mr Davis has been a war and foreign correspondent, a TV producer for 60 Minutes and 20/20, a newspaper editor, a documentary film maker for the BBC, and has taught journalism.
