I've greatly enjoyed Getting Better: Why Global Development Is Succeeding by Charles Kenny. (By the way, he's in London talking about the book at the ODI on Thursday 10th – webcast too.) The general message is that there's certainly inequality and poverty but nevertheless there have been huge improvements in the quality of life in poor countries. Life expectancy, health, education – in important areas of life, the past generation or two have seen tremendous advances even in countries where GDP per capita has barely increased at all.

The book starts with a survey of the phenomenon of 'divergence, big time' rather than convergence in GDP per capita, along with economists' lack of understanding of the process of economic growth. There's an amusing chapter about the way pretty much every silver bullet theory of economic development has cycled in and out of fashion ever since the 18th century – Jeff Sachs as Montesquieu redux. (Mischievously, Kenny also points out that although Sachs now sees geography as destiny, more or less, he had argued in 1996 that with better policies Africa would have grown 4.6% a year faster than it actually did.)

The early chapters also, though, note some of patterns with which any theory must be consistent. For example, that head starts matter, or wealth breeds wealth. Bill Gates's parents were in the top 1% of the global household income distribution, and if you can't be born to rich parents in a rich country, you should at least move to a rich country (this is Mancur Olson's 'Big Bills Left on the Sidewalk' (pdf) point – immigrants from Haiti to the US become more productive overnight). In other words there is an important stickiness to prosperity, over time and between people.

Kenny also makes the forceful point that to the extent that environmental concerns pose limits to growth (and he, like most economists is a bit sceptical), then:

(a) it's not population but consumption that's the limit. In 1679 Antoni van Leeuwenhoek calculated the Earth's carrying capacity at a population of 13.4 billion people, a figure that still seems correct;

(b) the absolute poor need more consumption so if there's any sacrifice to be made it must be made by the rich. “Sterilize the world's billionaires first and then move to a one-child policy for Switzerland, Luxembourg and the United States.” Doubling the incomes of the 650 million poorest people would amount to the same as a 1% income loss for the 650 million richest (pp67-68)

The book is also optimistic about the spread of education, of democracy – and it was published before people in North Africa and the Middle East started to demand political freedoms – and a long-term trend towards the unacceptability of violence. (This latter was a theme of Paul Seabright's terrific The Company of Strangers – or here's a video of his talk on the book).

Getting Better ends with a call for 'realistic optimism'. As he notes, it's odd that it's currently people on the right wing of politics who are optimists, at least relative to the dystopian, anti-trade and anti-globalisation left. After all, he argues, if you're not optimistic about the possibility of progress, how can you make any case for aid? There's certainly something odd and dispiriting about the fashion for despair about the possibility of improvement among so many so-called 'progressives'.

I myself am more of an aid sceptic than Kenny seems to be – only last night I met a woman who'd worked in Afghanistan for four years only to conclude that western governments are pouring in so much aid money that it's embedded corruption and destroyed all other economic activity. It's not wasting money on a rent-seeking aid industry that matters so much as examples like this of aid proving actively counter-productive. But that's a different story.

However, I do agree with Kenny's conclusion. GDP is a useful indicator but not one that tells the whole story. A wider view of what constitutes the good life – something for which we can turn to philosophers through the ages – gives us a wider perspective on progress. And the prospect of progress is something well worth believing in.