Davis, who presents the BBC Radio 4 Today programme and was speaking in the Newington Green Unitarian Church's annual Richard Price Memorial Lecture, spoke passionately about the value of honesty within all communication professions - especially journalism.
"News organisations get a story and have to make it sound better than it is. And a lot of people involved in communications would say this is sheer professionalism and it's what you should do," said Davis.
"But is this right? Are we really doing ourselves a favour by doing this?"
'Thou shalt not lie' is journalism's ethical code, which gets extended to 'thereafter you can mislead people as far as you possibly can', he said.
"We're all aware of this ethical code, but it's not sufficiently restrictive," Davis said.
The problem with misleading and dishonest reporting isn't that it's unethical, it's that it's unintelligent, he said.
"Being misleading is self-defeating because generally, you'll get caught. Professional communicators should be much more upfront, modest and honest."
Direct honesty can pose problems for people working in communications, he said, adding that 'when people are brutally honest they do get pilloried by the press'.
"There's also the problem that if everyone else is lying and one person tells the truth they won't get believed – sometimes it seems like you need to lie to keep up," said Davis.
"There's no point in us condemning Alistair Darling, for instance, for being honest about the economical situation in his article in the Guardian. We can't demand that he says something he doesn't believe just to reassure us."
News gets tiresome if it's not expressed in the most direct and honest way, Davis said.
"We should try, in communications, to be as honest as we can," he said.
"Because it's not just that it doesn't work, it's that it doesn't fool the people you want it to - you only fool yourself. And you do this at your own peril, because, as a journalist, that's a terribly dangerous thing to do."