Book excerpt: Aesthetic judgements that are formed on the basis of testimony are commonly held to be defective, illegitimate, or otherwise problematic. This book assesses the debate surrounding aesthetic testimony and argues for the surprising conclusion that this widespread view is mistaken. Aesthetic testimony is in no way inferior as a source of judgement when compared to either first-hand aesthetic judgement or testimony concerning non-aesthetic matters. Alongside establishing this position (an extreme form of 'optimism' concerning aesthetic testimony), Jon Robson also responds to the most prominent arguments for the opposing view ('pessimism' concerning aesthetic testimony). Along the way, it also re-examines our understanding of the norms which govern both judgement and assertion in aesthetics.