Boyd Tonkin: This year, how about some new year's irresolution?

Changes of mind lie at the core of almost every breakthrough in science, art and thought

This is the season when, for a day or two, millions of people delude themselves into thinking that fixed goals, firm purposes and rock-like convictions will bring happiness. Set up some distant destination whether of weight loss or career progression and trudge doggedly towards it, advise the secular priests of self-improvement. But every lifestyle guru makes one basic mistake. They confuse integrity, which matters, with inflexibility, which doesn't. So why not abandon the narrow path to disappointment and opt instead for some new year's irresolution?

Make 2008 the year in which you choose to change your mind. Because truth, like time, is forever on the march. You will be in the best possible company.

Changes of mind lie at the core of almost every breakthrough in science, art and thought. From Copernicus to Einstein, Leonardo to Picasso, James Joyce to Bob Dylan, lasting innovations rest on a rupture with the principles of the past. Darwin's long struggle with his own evidence for evolution by natural selection stands as one of the greatest feats of self-persuasion in history.

Ludwig Wittgenstein created one revolution in philosophy with his Tractatus. Later he decided it was fundamentally misconceived and created another with the Philosophical Investigations. And if Alan Turing had never revised his view about the practicality of his highly abstract research on "computable numbers", then the machine on which I write this piece would not exist.

The constant testing of doctrines and axioms is how cultures evolve. For that matter, the kind of modern urban life that hosts paradigm-shifters in art and science became survivable only because Victorian-era doctors had changed the mind of civic authorities about the true sources of epidemic disease. Apocryphal it may be, but the motto of every free-thinker should be the reply John Maynard Keynes reportedly gave when accused of altering his stance on monetary policy: "When the facts change, I change my mind. What do you do, sir?"

From tomorrow morning, we can all sample the reasoning that drives shifts in position by a selection of leading scientists and social thinkers. Since 1998, the splendidly enlightened Edge website ( www.edge.org) has rounded off each year of inter-disciplinary debate by asking its heavy-hitting contributors to answer one question. This time, the new-year challenge runs: "What have you changed your mind about? Why?". I strongly recommend a visit to anyone who feels browbeaten by fans of that over-rated virtue: mere consistency.

Yet in public life, mind-changing attracts the charge of weakness, even when it reveals strength. The taint of flip-flops and U-turns lingers, however justified the altered course. "The lady's not for turning," trumpeted Margaret Thatcher even though she frequently did. Besides, she had come to power precisely because an intellectual project of mass persuasion had convinced many voters that the unchained market would deliver better results than welfare corporatism had.

From the anti-slavery pamphlets of Thomas Clarkson to the global-warming movies of Al Gore, every significant social movement has been fuelled by reformers with changed minds. And one abiding flaw of the centre-ground politics that governs Britain is that it benefits the dark arts of presentation over the open warfare of persuasion. If many voters seem to have drifted lately from brand Brown to brand Cameron, then that has less to do with any deep-seated shift in outlook than with the reduction of political choice to preference-switching on the consumer model.

All parties, and much of the media, share the blame for this debauching of debate. Vince Cable gained acclaim as a modern Demosthenes because he floored the PM with his Stalin-to-Mr Bean quip. How sad that a custodian of the party of supreme persuaders from John Stuart Mill to Gladstone and Lloyd George should win brief fame thanks to a knack for glib soundbites.

Starved of genuine argument, fearful of straying off-message, the political class bows down to the tricks of the roadside hoarding and the commercial break. Outside the intellectual desert of Westminster, thankfully, the business of changing minds carries on as energetically as ever. Human responsibility for climate change ranks as the strongest example today of the interplay between new discoveries, revised opinions and even modified behaviour.

I have changed my mind about everything from country-and-western music to the concept of human nature. I hope and expect to make more changes in the coming year. In the meantime, it would violate the spirit of openness and flexibility to push this proposition too far down the road of dogma. So, if you planned to give up smoking during 2008: please don't change your mind.

b.tonkin@independent.co.uk