I have to confess to being a serial non-finisher of popular books that take on the big questions. I gave up on page 11 of A Brief History of Time, because I did not understand what I was reading, and only managed two chapters of The God Delusion before becoming so irritated by the author that I developed distracting fantasies of setting up a new religion that would worship Richard Dawkins as the Universal Supreme Being. Peter Rabins is well known to the readership of International Psychogeriatrics for his decades of leadership of productive research groups at Johns Hopkins and as a thoughtful and genial presence at international meetings. But he is familiar to a much wider lay audience through his co-authorship of The Thirty-Six-Hour Day (Mace and Rabins, 2006), a landmark guide for families caring for people with dementia, which has sold over two million print and e-book copies. He is about to become very famous indeed and I suspect that our colleague has written a book that will march remorselessly up the non-fiction best-seller tables. Perhaps most importantly, he has produced a beautifully written and informative book that is both a pleasure to read and pretty much impossible not to finish.

Rabins explains that, as a psychiatrist, he is often asked questions about causality that he finds difficult to answer. For example, the question from a patient, “Why have I become depressed?” could evoke an answer involving the effects of genes, early experiences, and current life events. But then why do these factors cause depression in one individual but not in another exposed to similar background and experience? How should we begin to approach our response to such questions, and should there be agreed standards by which we can judge the adequacy of our answers? Should we accept that there are some questions that we just do not have answers to? The book encourages the reader to believe that causal relationships – however complex they may be – can be found if you know where and how to look for them. As an intellectual pathway for this, Rabins proposes a novel three-facet model of causality to guide the reader toward a systematic and best approach to each question that he or she might encounter. The first facet consists of three conceptual models of causal logic (categorical, probabilistic, and emergent causes), the second facet describes four levels of analysis (predisposing, precipitating, programmatic, and purposive causes), and the third one describes the three methods of logic (empirical, empathic, and ecclesiastic) that could be used to investigate cause. This sounds more complicated than it really is and Rabins patiently leads the reader through the application of each model, analysis or method using examples from basic science, philosophy, law, mathematics, and religion as he goes. By halfway through the book, I found I had started to apply the model to the question posed in the text of a particular chapter in anticipation of the reveal of the worked-through argument. I felt quite proud to have done so because, to be perfectly honest, the limitations of my working memory meant that I initially struggled to keep the model on-line in order to apply it. This is a book that rewards a little intellectual effort. Rabins is a smart and incredibly widely read guide, but he is leading the reader through intellectually steep and rocky terrain. The book works because the subject areas covered are truly interesting and the text is so well written. Endearingly, the reader learns much more about Peter Rabins than his thoughts on causality, and the personal warmth and nature of the man season every paragraph. As he considers a question from the nature–nurture debate, and applies his model to its solution, Rabins takes us on a typically thoughtful journey that begins in a personal experience.

While taking the lift at a scientific meeting in Japan, Rabins notices that he is having the unusual experience (for him – he is five feet four inches) of looking down on the heads of his fellow travelers, who he also notices are of the same age as him or older. On subsequent lift rides, he finds that younger Japanese are either taller than him or stand at face level, as is the case with Americans when he is at home. The explanation must involve access to better nutrition during childhood and adolescence since the Second World War, but since the heritability of height is known to be greater than 0.9, how can he explain the dramatic difference between the height of these different generations? By applying his programmatic level of analysis to the problem, Rabins is able to provide a much more integrated and satisfying explanation than one involving simple competition between the forces of nature and nurture. When adequate nutrition is available, genes are a predisposing cause of final height, while the environment acts as a precipitating cause. Hence, height appears to be largely genetically determined. When nutrition is restricted, the environment becomes a predisposing cause and exerts a major determining effect. Through recognition of nature and nurture as interacting factors that make mutual and independent contributions to height, Rabins’ Japanese lift ponderings deliver an answer to the problem that is complex, but which has a great ability to account for what he has observed.

In the final chapter, Rabins tests the utility and limitations of the model when he applies it to six specific issues, half of which (Alzheimer's disease, human aggression, and the aetiology of depression) are home ground for psychiatrists. His analysis of causality in the complicated areas that we deal with every day will make you think differently about your patients and how they have reached you. Indeed, reading this book will make you think differently about why everything happens.

This is a book that you'll want to share with your friends – but you won't want to lend them your own copy. A colleague found my review copy on my desk and, after skimming the first few pages, asked if he could borrow it when I was finished. I bought him one on Amazon.