When I was an undergraduate, I unexpectedly came into a small amount of cash as I’d been underpaid for a summer job. Rather than fritter (all) the money on beer, I thought I’d do some good and sponsor a child in a third world country. £144.00 a year seemed a small price to pay to salve my shame at being born relatively rich.

My naiveté was shattered when I realised that the whole child sponsorship thing was just bait to get well-meaning people like me onto a mailing list so I could receive a begging letter from the charity every month – a typical opening sentence was “Imagine waking every morning to hunger gnawing at your stomach…” I also discovered the money was not going directly to the child concerned, but unspecified “projects in the area”. My dream of dragging one child out of the mire of poverty had absolutely no basis in reality. I’d been had.

When I later found out how much the CEO of that particular charity earned, I got very angry indeed – no hunger gnawing at his fat cat stomach I can tell you. I concluded the charity industry was just another way of keeping the rich rich and the poor poor – and one which was much less honest than the others.

Reading William MacAskill’s Doing Good Better has blown that cynicism out of the water – not a bad effort for such a short, punchy book. MacAskill points out that if the only good thing that all international development aid in history has ever done is eradicate smallpox, then it is still money well spent, given what we spend on combating diseases in the developed world. He notes that many charitable ideas are worse than useless, and that even worthwhile projects have an difference in impact from the worst to the best of up to a factor of 500.

So, MacAskill argues, we should give to charity and make other acts of altruism, but instead of following our emotions, we should apply some highly rational analysis to our options to make sure our money is delivering. That analysis includes use of metrics such as quality-adjusted life year (QALY) and robust randomised controlled testing of different options. Doing this type of rigorous assessment, for example, revealed that deworming children has a much, much bigger positive effect on their education (and thus their life prospects) than an ‘obvious’ and sexier solution such as donating school books.

Likewise, MacAskill shows, many people would be advised not to work in an altruistic job unless they have particularly in-demand skills (such jobs are usually over-subscribed so it makes little difference whether you do them or someone else does), but would make a bigger impact by earning a higher salary in a conventional job instead and donating a chunk instead.

When he moves into issues, such as climate change, MacAskill takes a similarly hyper-rational approach as Mark Lynas, blowing myths about carbon offsetting out of the water. He points out that, if you want to save a tonne of carbon a year, you can either go veggie (which MacAskill already is), or buy the equivalent offset from, say, Cool Earth for just $5. You can easily save more carbon than you emit by donating a modest amount to an effective scheme. Fairtrade, on the other hand, is exposed as structurally unsound.

The one point where I felt MacAskill was getting a bit too carried away with his contrarian thesis  was sweatshops where he made the ‘better than hard scrabble farming’ argument. That’s true if those are the only two options, but there is a third – manufacturing jobs with decent working conditions.

If you give money to charity on a purely emotional basis, then you should read this book – it will make your money go further and keep charities on their toes. If, like me, your donations have dried up due to scepticism about whether I’m doing good or paying someone to make me feel good, you should read this book. It may be a rather cold, hard look at altruism, but in my opinion that’s exactly what’s needed.