David Haig

R700 Current Biology 25, R693–R710, Augu Ballard roots his development in the language of computation, the only tool available with which we can express the full breadth of necessary concepts, from mathematics to logic, representations, input and output, algorithms, control, systems, memory, interaction, and more (see also [8]). He uses this full breadth of computational methodologies far more effectively than seen previously and thus makes a more powerful statement for their utility than David Marr or others. The path Ballard presents is perhaps best considered using his own main argument: it is an abstraction. As an abstraction, and if a correct abstraction, future efforts should be able to defi ne the subelements of his plan in such a way so that the overall plan remains intact and does not deviate. How will we know if this is the correct path? What does it predict and how can we test those predictions? The path laid out is suffi ciently rich to motivate much experimental work that would answer these questions. I feel that Ballard has successfully navigated the oceans of available constraints, and plotted a course that will provide guidance for quite some time to come. This book is a ‘must read’ for anyone interested in understanding the human brain.