The central premise is that to advance ecology effectively as a discipline, ecologists need to be able to establish conclusive answers to key questions rather than merely proposing plausible explanations for mundane observations. Ecologists need clear and honest understanding of how we have come to do things the way we do them now, the limitations of our approaches, our goals for the future and how we may need to change our approaches if we are to maintain or enhance our relevance and credibility. Readers are taken through examples to show what a critical appraisal can reveal and how this approach can benefit ecology if it is applied more routinely. Ecological systems are notable for their complexity and their variability. Ecology is, as indicated by the title of this book, a truly difficult science. Ecologists have achieved a great deal, but they can do better. This book aims to encourage early-career researchers to be realistic about their expectations: to question everything, not to take everything for granted, and to make up their own minds.