The retreat from alien facts into the comfort of familiar beliefs has been identified as a factor in the political upheavals during 2016 in Britain and the USA.

The Oxford English Dictionary has chosen “post-truth” as its Word of the Year for 2016. The facts no longer matter. What matters is whatever people believe the facts to be, and there is no shortage of politicians willing to provide comforting pseudo-facts to order.

If people wish to believe that the USA has been overrun by immigration from Mexico, Donald Trump will build a wall. As a matter of fact the flood of Mexican migrants into the US subsided many years ago. There is now a return flow southwards of retiring migrants from earlier generations, and net migration is negligible. There has even been a net flow south in some recent years. But who cares about boring statistics?

Coal mining precedent

It has become an article of faith in British politics, or at least on the left, that the UK coal mining industry was deliberately destroyed by Margaret Thatcher in the 1980s. As it happens (boring facts), employment in the pits was already at less than half the 1950 level by the time Mrs Thatcher assumed office in 1979. The volume of output peaked around the late 1950s and has been on a steady downward trend ever since. What little is left will be gone a decade hence.

By the time of Thatcher’s confrontation with striking miners in 1985, coal output had been falling rapidly for almost 30 years. At the Brexit referendum the former coal mining areas, including the once-upon-a-time pit towns of south Wales, voted heavily against continued EU membership, partly in response to Labour leader Jeremy Corbyn’s promise to somehow reopen coal mines. Britain has been digging up coal on an industrial scale longer than any other country in the world and, guess what? It’s nearly all gone (boring fact).

A striking feature of the Trump campaign in the USA was his success in securing support in parts of the country where the coal mining industry had gone into decline. But the decline is very recent and has nothing to do with imports, from Mexico or anywhere else. The USA imports some coal into the Gulf ports from across the Caribbean in Colombia but exports are far greater. There are no coal imports from Mexico.

The recent decline is due mainly to competition from natural gas. American natural gas, that is. But no matter, Donald Trump supporters waved “Trump Digs Coal” banners at rallies all round Appalachia, where mines have closed due to gas competition but also because mines tend to close when the stuff you have been digging up for the last couple of centuries is all gone.

People regard the things they believe as comforting possessions, incontestable by anything as dry as official statistics

It is easy to dismiss the voters of Appalachia and of south Wales as foolish or naïve. If they expect the Donald Trumps or Jeremy Corbyns of this world to keep uneconomic coal mines open forever they are both and deserve the coming disappointment.

But people regard the things they believe as comforting possessions, incontestable by anything as dry as official statistics. Non-factual beliefs are harmless in most areas of life – the Cork hurling team still has supporters, for example, and I am about to send off a cheque for my Shamrock Rovers season ticket.

But when serious political decisions get to be based on blind faith or demonstrable untruths there are serious costs. It is the unappreciated role of a free press to insist that the numbers matter, that they are produced by reputable statistical agencies and that they are reported to, and understood by, the general public.

The quality of our democracies in the years ahead will reflect the diligence of the media in deflecting the onward march of post-truth politics. Every good wish for 2017.