"I''ll bet it will tum out that brains use both mechanisms, in different centers. " Much of my waking life and that of many of my friends is spent racking our brains over how brains work. This book claims that good science is often a form of betting on the outcome of research-the stakes being time and reputation and someone''s money. Some scientists, to be sure, claim they avoid leaning this way or that, in the name of keeping an open mind. I recommend making expectations explicit in order to design controls against unconscious influence, formulate alternative outcomes more clearly-and to add zest. Both the immediately upcoming experiment and the expected result of many long years of work by many people after one is gone are proper subjects for betting or the most informed and serious guessing. The working title for this collection of new and old papers was for some time "Betting on how brains work" and then "Betting on brains. " It goes without saying that the book will not answer the title question but will speak to it, in particular making a series of propositions that I think are more likely to be confirmed by future research than the alternatives we can presently recognize. It follows that a significant message, implied in many chapters of the book is this.