Where to begin? This book is the first of a classic trilogy by renowned American philosopher Alvin Plantinga. The trilogy concerns what, exactly, is required in order to actually know something. Knowledge must be at least true belief, but it must also be more than that; whatever this mysterious extra element is, we might call it 'warrant'. In this volume, Plantinga examines a wide variety of historical and contemporary theories on what might suffice for 'warrant', and systematically rebuts all of them – mostly because none of them can deal adequately with situations where our brains just aren't working as they should. Plantinga is fond of using delightfully bizarre thought experiments, many of which involve bizarre experiments performed on humans by scientists from Alpha Centauri. These are the fun bits that enabled me to get through what was otherwise a very dry book. (Nor could a book of this sort be anything but dry, so one mustn't fault Plantinga in any way for that.) Still, it's given me a lot to think about, and I hope to get around to reading the other two volumes later on. ( )