Most days, I start by reading the news, but faced recently with a Brexit headline about ‘not negotiating the unnegotiable’ I admitted defeat. I could bear it no longer. I closed the page, too depressed to read on. Perhaps it’s me. I voted remain. Perhaps I’m in denial. Not coping. I’ll admit to that.

In Kübler-Ross’s five stages of grief – applicable to any life-changing event – you might commonly experience denial then anger, depression then bargaining, before finally moving to a state of acceptance.

Okay. I can testify to being furious most days since the EU Referendum result, in which the British public voted 52% – 48% for the UK to leave the EU.

Depressed by it all? Yep. That too. Ticks box.

A state of acceptance? The only state I’d happily move to is a European one. Otherwise, I’m not planning on acceptance any time soon.

And why should I? The British have been sold a pup. The Leave campaign made an emotional bid for the hearts of the electorate. Michael Gove, then Conservative cabinet minister and leading Leave campaigner, famously derided the evidence-based approach of the Remain campaign. ‘People in this country have had enough of experts,’ he said.

The Leave campaign’s key claim that the UK sent the EU £350million a week was challenged time and again. The UK Statistics Authority called the figure ‘misleading’ saying it ‘undermined trust’ in official statistics.

Did the Leave campaign care? Not a jot. They continued to distort and evade, refining their narrative, creating a Trumpian plea to make Britain great again, the irony of the lower-case ‘great’ seemingly lost on them, and then ratcheting up fears around immigration for good measure.

Analysts have since declared an age of post-truth politics, one in which emotion trumps (sorry) truth. Journalist, Michael Deacon, neatly summarised the challenge: ‘Facts are negative. Facts are pessimistic. Facts are unpatriotic.’

Should we accept this? No, we should not.

And this brings me, in a way I might never have expected, to Descartes.

Descartes. Seventeenth century French philosopher, Dutch resident, most famous perhaps for his dictum, Cogito ergo sum: I think, therefore I am, or, better, I am thinking, therefore I am.

Sometimes, when we hear or see things too often, they lose impact – the meaning erodes. Think of van Gogh’s sunflowers, endlessly reproduced on mugs, place mats, key fobs. But stand in front of the painting and you see it again, anew.

Cogito, ergo sum: oft repeated, but what exactly does it mean?

Descartes lived in deeply superstitious times, when women were burned alive as witches and even a minor disagreement with the Catholic Church risked a charge of heresy. Yet it was a time of change too. The Copernican view of a heliocentric universe, which placed the sun, not the Earth, at the centre of cosmos, was beginning to gain support, both from Galileo and Descartes. For this, Galileo was placed under house arrest and ordered to burn all copies of his work, The Dialogue Concerning the Two Chief World Systems, published in 1632. Descartes also came close to destroying his work and decided against publishing his The World, saying the world was not ready for it.

Aristotelianism still dominated intellectual thinking – a world view, predicated upon the senses. Descartes realised, as we do now, that the senses deceive. But if the senses deceive, and cannot be trusted, how then should the world be understood? What, indeed, could be said to be true? Was anything certain?

Certainty mattered to Descartes. To find out what was certain, he questioned every assumption, using a method of doubting until he reached a point when he could state unequivocally: this I know to be certain. Only from this certain point, the strongest foundation, was it possible to progress; to build knowledge, incrementally, step by step. In order for knowledge to be certain, it could not be doubted.

I am thinking, therefore I am: Descartes knew himself to be thinking, he could not doubt that, therefore he must exist. His thoughts could not exist without him, thinking them. Simple, eloquent, profound. Brave, defiant, certain.

Why does this matter? Because Descartes’ reasoning enabled us to understand the world in certain terms. This marked a fundamental shift away from understanding based on feeling, towards knowledge built on rational insight, on fact.

Here’s a fact. People have always moved across borders, between countries, and Descartes was one of them. He lived most of his adult life in the Dutch Republic. He was a migrant, and Holland provided refuge in a continent ravaged by war and religious intolerance.

Writing about Amsterdam in 1631, he said, ‘…I could live here all my life without ever being noticed by a soul. I take a walk each day amid the bustle of the crowd with as much freedom and repose as you obtain in your leafy groves, and I pay no more attention to the people I meet than I would to the trees in your woods or the animals that browse there. The bustle of the city no more disturbs my daydreams than would the rippling of a stream…Whenever you have the pleasure of seeing the fruit growing in your orchards and of feasting your eyes on its abundance, bear in mind that it gives me just as much pleasure to watch the ships arriving, laden with all the produce of the Indies and all the rarities of Europe. Where else on earth could you find, as easily as you do here, all the conveniences of life and all the curiosities you could hope to see? In what other country could find such complete freedom, or sleep with less anxiety, or find armies at the ready to protect you, or find fewer poisonings, or acts of treason or slander?’ (Descartes, letter to Balzac, 5th May 1631).

The Dutch Republic provided space for Descartes to think and work: it gave us one of the world’s most important thinkers. All of Descartes’ major work was produced there, and he finally published Discourse on Method in 1637.

Descartes gave us a way to determine truth; a way to stand up to liars and deniers, to peddlars and fools. Michael Gove et al might be victorious, but they should be ashamed.

It is not enough to scorn their anti-intellectualism. Whether you were for Leave or for Remain, the onus is on us all to hold truth dear. And to defend it.

September 16th, 2016.

@guingb