‘Don’t confuse pessimism with profundity,’ warns Steven Pinker at the end of a book he knows will have many confusing positivity with shallowness. Outside of California, where belief in the almost spiritual power of technology not just to save humanity but massively to improve it reigns, the cognoscenti revel in pessimism. Any suggestion that the state of mankind might actually have been getting better over time is dismissed as the discredited Whig version of history. Defenders of reason are accused of a faith more naive than that of religious believers, who at least understand the pitiful, fallen state of humankind.

Since publishing The Better Angels of Our Nature in 2011, Pinker has become the favourite punchbag of these world-weary prophets of doom. Over nearly a thousand pages, Pinker marshalled a stack of evidence to show that violence has been in long-term decline across the world. Fans of nominative determinism will be pleased to note that the attacks on rosy Pinker were led by the gloomy John Gray, who argued that, far from being evidence-based, Pinker’s belief in progress merely ‘testifies to our enduring need for faith’.

If so, Pinker’s new book shows that faith stronger than ever. Enlightenment Now adds to the good news on violence further arguments that we are healthier, safer, better educated and more equal than ever before. The number of people living in extreme poverty has been falling on average by 137,000 a day for the last twenty-five years; life expectancy in Kenya grew by a decade between 2003 and 2013, meaning that someone living in that time would have aged by ten years yet still be no closer to death; famine has been all but eradicated outside Africa, where it has also steeply declined. Human flourishing has been widening for a couple of decades and the root cause is the Enlightenment, with its commitment to reason, science and humanism.

Those whose fear of sunlight is such that they won’t even take the hypothesis seriously should adapt John Rawls’s famous ‘veil of ignorance’ thought experiment and ask themselves whether, in the event that they knew nothing about their gender, class and sexuality or the opportunities available to them, they would rather be living today or at any other time in human history. The fact that for more than half of humanity – all women – the present age is better than any other should tip the balance for most participants. It’s not just for women that things have improved. In almost any other time and place, the vast majority of men were dirt poor, vulnerable to death as a result of minor infections and diseases we give no thought to today, illiterate and subjected to periodic famines and droughts. In the Athens of Plato and Aristotle, you’d as likely have been a slave as a citizen.

Pinker’s claim about the state of the world is little more than a statistically supported version of these obvious truths. Why, then, does it generate so much hostility? Although it is possible to question some of the data Pinker relentlessly piles up, the majority of objections simply get him wrong. Most obviously, he never claims that progress is inevitable or irreversible. When Pinker says ‘a belief that things will always get better is no more rational than the belief that things will always get worse’, he could be quoting Gray.

Nor does he claim that the world is wonderful as it is. Highlighting how far we have come is not to deny that we have much further still to go. Pinker points out the irony of being called ‘Panglossian’ because, in the figure of Professor Pangloss, Voltaire was satirising not Enlightenment optimism but the religious theodicies that explained away human suffering on the grounds that we already lived in the best of all possible worlds. Pangloss, says Pinker, is technically a pessimist because he doesn’t believe the world can get any better.

Evidence may show that improvement has been a trend, but when Pinker argues that it is more likely to continue than not he moves from fact to judgement. The data of the past is never a completely reliable indicator of the future. A graph showing a decline in the number of deaths caused by terrorism in the USA published on 10 September 2001 would be no proof at all that people going to work the next day had a close to zero risk of being killed in a terrorist attack. A nuclear war on the Korean peninsula or a bioterrorism-induced pandemic could, in an instant, rewrite the scorecards for civilisation in the 21st century. Like Aristotle’s warning never to call a life good until it has ended, is it not premature to cheer the state of the world when its future remains so uncertain?

Once again Pinker is ahead of his critics. Indeed, part of his purpose is to remind us that the future is not guaranteed to be good unless we continue to draw on the resources of science and reason that have taken us so far. He’s also clear that climate change poses a very serious risk indeed. However, when it comes to the other existential threats we supposedly face, he argues that sober minds would judge them unlikely to bring us down.

For example, most of us tremble to think about the possibility of a terrorist bioengineering a virus that could wipe out most of humanity. However, far from it being inevitable that someone will eventually succeed in this, it is something that would be incredibly difficult to pull off. Viruses trade off virulence against contagiousness. The more deadly a virus, the less chance its carrier has of living long enough to pass it on. Even if we think it is only a matter of time before a human-made virus is unleashed on the world, the chances that it would do worse than the 1918 flu pandemic that killed 3 to 5 per cent of the world’s population is vanishingly small.

Persuasive though his reassurances are, I still found myself resisting them, driven less by reason than by the superstition that it would be tempting fate to toast our good fortune before the fat lady has sung. That instinctive reluctance to count chickens serves us well if it guards us against complacency. But Pinker is in no way complacent. To accuse him of smugly sipping cocktails at the End of History cafe is simply to ignore his repeated calls to work for the better future that is there for the taking, but also for the losing.

Pinker’s thesis is most vulnerable where it seeks to explain the causes of our present good fortune. For Pinker, almost all that we have today is thanks to the Enlightenment. Once a large part of the world had embraced science, reason and humanism, humankind could begin to address its real problems with methods that worked. This is deeply unfashionable in bookish circles, where the Enlightenment is routinely blamed for the dehumanising, utilitarian rationalism that led to Auschwitz, or for the loss of spiritual values that leaves us with our shallow, materialistic, empty lives.

The desire of educated people to put down Enlightenment values would seem to be the worst kind of ingratitude when it comes from those who have benefited most. Their animus has three main sources. The first, religious resistance to the secularisation it set in motion, is easily enough understood, and for many of us just as easily dismissed. The second is a resistance to scientific overreach that dismisses as useless or superstitious anything that can’t be measured and tested. In reality, however, there are few bone-headed defenders of this ‘scientism’ out there. As long as science is not deified, it should rightly be praised. The third is the belief that reason itself is a thin veneer covering human irrationality, greed and malice. But as Pinker points out, ‘no Enlightenment thinker ever claimed that humans were consistently rational.’ Indeed, it is only because we have rationally, scientifically studied the mind that we have become so aware of our own deficiencies. Without reason, many of our darkest corners would have remained hidden.

Pinker’s version of history is somewhat simplistic. The Enlightenment did not emerge out of nothing and the role of two millennia of Christianity can’t be swept under the carpet. Much as I’d like to be able to agree with Pinker that secular humanism is one of the driving forces behind progress, since hardly anyone was a convinced atheist until recently, this can’t be quite right. Nonetheless, it can be no coincidence that the rise of trust in reason and science over religious doctrines and authority correlates with almost all the improvements Pinker charts.

Enlightenment Now is not perfect. Pinker shares a common Anglophone prejudice against modern European philosophy, lumping most of it together under the heading of ‘postmodernism’ and attacking the grotesque version of Nietzsche created by fascists and the alt-right, not the more complex and interesting figure most scholars would recognise. In a work of such breadth and scope, small lapses like this are inevitable, but are far outweighed by the clarity, force and evidential weight of his central arguments.

By the time you read this, something truly dreadful might have blighted the world. Pinker does not prophesy that this won’t happen; he simply reminds us why it should not and need not, as long as we don’t give up the notion of the emancipatory power of reason to help illuminate the way forward. If that is naive, even more naive is the belief that despair, fatalism or superstition supplies a credible alternative.