In Wall Street, at least when I last visited the place – they may have melted it down by now – there is a statue of a charging bull. It was the logo of one of those investment houses that suffered most during the 2008 banking crisis, but also a symbolic hymn to the so-called bull market.

It is one of those disastrous fantasies, it is closer than is entirely comfortable to the other statue of the bull the Israelites worshipped in the desert to the rage of Moses, and it possessed the last generation for at least the last decade. You can see the bull statue, the modern one, as a celebration of deluded optimism.

The bulls were worshipped, but the bears were ignored or dismissed as Cassandras. But of all the bears I’ve ever known, David Fleming was perhaps the most optimistic. Although he believed that the bullish fantasies would unravel – as they have begun to – he also believed that humanity could survive. In fact, it is pretty clear in his book Surviving the Future that he believed we would thrive.

I knew David as one of those imaginative and innovative economists who populated the fringes of the New Economics Foundation in its early days in the late 1980s, spreading hope and ideas.

One of his ideas, which carried all before it in the decades that followed, was what he called Domestic Tradable Quotas (DTQs), the idea of a kind of personal carbon allowance that could be traded – a kind of basic income. It was ingenious and very simple. The mainstream called the idea TEQs, or Tradable Energy Quotas. It was somehow typical that the mainstream insisted on calling it something different.

Unfortunately, David died too young, one of a number of those economic pioneers – including Richard Douthwaite and John Hatfield – who worked so hard and so optimistically to kick-start a greener economics and who have so sadly departed recently.

It is this book’s central paradox that makes it so exhilarating and so different from most of the books bearing its kind of title, which tend to be deeply depressing: David believed not only that the present dispensation could not last, but also that humanity could and would survive in radically decentralised communities. This book explains how – and how that kind of life may also be more successful, more fulfilling than the one we are living at the moment.

Like all sceptics, David had a radical’s ability to follow his own logic wherever it took him. That is a rare ability and it brings the book alive, together with the unexpected erudition. “His mind wasn’t a linear thing,” writes Rob Hopkins in the introduction. “It leapt from one thing to another, making connections that no one else would.”

It is on such a journey, for example, that David takes the word ‘lean’, which means something very particular to the book, and not quite what you expect if you are familiar with the idea from Japanese car plants. In essence, the approach seems to be about shifting society from being very efficient about money and very wasteful of raw materials to being rather the other way around.

This implies unnecessary waste. But actually, what really excited me about the book was not so much the chapters on sex and carnival, but David’s central idea of “slack economics”: that some slack in any kind of system – families or villages or economies – is necessary for them to be resilient and humane and effective.

I think he was right. This book is not just testament to David Fleming’s rightness, but also to his civilisation and his humanity. It is also rather good testimony to his ability to write.

David Boyle is the author of Scandal: How Homosexuality Became a Crime.