Stefan Stern: Nobody tells the whole truth. But is a bit more of it too much to ask?

We live in a post-fact world where powerful people are relaxed about lying

(James Benn)

Last week, they interred the ashes of the man who urged us to "live in truth".

Vaclav Havel's funeral was, perhaps unexpectedly, quite uplifting, a reminder that speaking the truth with courage and conviction can still be the most powerful weapon of all. It can bring down governments and change the course of history. In the Arab world this year, the word from the streets has helped to overturn seemingly unshakeable dictatorships.

The less uplifting thought is that, elsewhere in the world, truth has been a casualty, caught in the crossfire of lies, self-deception and legalese that broke out repeatedly in 2011. Economic and political crises, such as the one we are living through, are sometimes called "moments of truth". Will the new year bring us a fresh outpouring of truth-telling and a healthy purge of the deceivers? Or will mendacity win out, again?

The Truth – an ambiguous and elusive concept, I know – has actually been in trouble for some time. In 1997, Peter Mandelson told the journalist Katharine Viner: "If you're accusing me of getting the truth across... that I'm trying to create the truth – if that's news management, I plead guilty." The recent Bush administration had a more troubling and grandiose view. An unnamed aide told Ron Suskind in 2004 that those who worked in what the source called "the reality-based community" did not understand "the way the world really works any more... We're an empire now, and when we act, we create our own reality... We're history's actors... and you, all of you, will be left to just study what we do".

This is not the cue for another discussion on the whereabouts of (non-existent) weapons of mass destruction. But three decades after Havel had told us to live in truth, the film-maker Michael Moore declared that "we live in fictitious times" (speaking at the Oscars ceremony in 2003), while the satirist Stephen Colbert coined the term "truthiness" to describe those things that we feel and know ought to be true, but sadly just cannot (and never will) prove. Anyhow, who needs mere facts when ambition and faith are leading you on? "I only know what I believe," as Tony Blair told the Labour party conference in 2004.

In the new year, we will have a US presidential election, quite possibly to be fought between those two fine Harvard men, Barack Obama and Mitt Romney. Harvard University's motto is "veritas". Will this campaign be a great moment of Truth? Maybe not. In fact, the economist Paul Krugman has already labelled former Governor Romney's efforts "post-truth politics". Last week, Romney stated: "President Obama believes that government should create equal outcomes. In an entitlement society, everyone receives the same or similar rewards, regardless of education, effort, and willingness to take risk." The wild inaccuracy of this assertion is hard to reconcile with the candidate's Mormon faith.

Back home, there may be a useful outcome to the ongoing Leveson Inquiry into the "culture, practice and ethics of the press". So far, proceedings have resembled a kind of truth and reconciliation committee, although probably with a bit more of the former than the latter. Together with the hearings of the Culture, Media and Sport Select Committee, this process has given us a crash course in legalistic jargon and evasiveness. The phrases "I have no recollection", "I do not recall" or "To the best of my knowledge..." have rung out again and again this year. And every time they have, another truth fairy has died.

The high/low point was probably the evidence given by the former Daily Mirror editor Piers Morgan, who was keen to support the apparently widely held view that senior executives could not really be expected to know what was going on in their organisations. Unfortunately for Morgan, he had already written about dubious and illegal newspaper practices in his memoirs. This put him in the uncomfortable position of having to cast doubt on his own book – almost accusing himself of being a liar. It had come to this.

The truth is we should not be too naive or idealistic. Nobody tells the whole truth all of the time. It would make life impossible. Families have secrets and unmentionables, as many will have been reminded this Christmas. When a husband is asked by his wife whether a certain outfit flatters her figure, or not, there really is only one sensible answer to give, regardless of the actualité. At work, we cannot always tell people we can't stand them, even if it is true. It is probably wise not to disagree with the boss too often, even if he or she is wrong and/or an idiot. And few saints or unflinching truth-tellers get to the top.

But there is a bigger, more worrying problem in this post-fact world where powerful people are relaxed about lying, or "creating their own reality" if you prefer. Never mind mere (moral) relativism: cynical detachment from truth is destructive and destabilising. The challenges that face us are so great that we really have to "confront the brutal facts", as the management guru Jim Collins puts it. The continuing nonsense of the eurozone is an example of what happens when a generation of political and financial leaders refuses to acknowledge the scale of the problems. When the Italian welfare and labour minister Elsa Fornero broke down while announcing necessary changes to pensions, that too was a belated moment of truth.

We need to start having "truthful conversations", says Dov Seidman, CEO of the ethics consultancy LRN. We will have to fix our problems ourselves, through our own actions. And our behaviour has to be rooted in a shared (and accurate) sense of reality.

"All I want is the truth," sang John Lennon in 1971. "Just gimme some truth!" In 2012, we will be confronted by some unpleasant truths about our economy and our place in the world. Will we be able to handle it? And will anyone be competent and courageous enough to lead us through it?

The writer is visiting professor in management practice at the Cass Business School, London