The title of this book could tempt a reader into thinking that charity is a logical business, in the sense that the work it does is determined by careful assessment of need, followed by the targeted application of resources.
But its theme is that charity is actually not logical: deprived areas usually have fewer charities than affluent ones, for example, and people are more likely give to a charity for personal reasons than for its proven effectiveness or the social priority of its cause.
That's why donkeys tend to get the dosh instead of drug addicts. It also plays a part in why politicians often find charities so frustrating: it's hard to steer or nudge them into activities and geographical areas that governments want to prioritise.
The book distils some of the research in recent years by the authors, two of the UK's most astute students of the voluntary sector: John Mohan, head of the Third Sector Research Centre at Birmingham University, and Beth Breeze, director of the Centre for Philanthropy at the University of Kent.
But it also interprets that research in the context of what is happening now in the world of charity policy and politics, such as the big society, the delivery by charities of public services and the work of the so-called "nudge unit".
Its main message is that charity, regardless of the hopes of politicians, is not a matter of the proportionate matching of needs and resources, and that the individualistic nature of giving means that this is unlikely to change.
For that reason it should be top of the bedside pile of Cabinet Office ministers who would like to understand more about the composition, strengths and limitations of the intrinsically illogical world of charities.
The Logic of Charity: Great Expectations in Hard Times, by John Mohan and Beth Breeze, is published by Palgrave Pivot, £30 Kindle edition, £45 hardback.