Throughout history, skepticism and the urge to question accepted truths has been a powerful force for change and growth. A healthy amount of skepticism is widely encouraged, but when is such skepticism legitimate and when is it problematic? Scepticism: A Very Short Introduction explores both the advantages of skepticism and how it can have unhelpful social consequences in generating distrust. It considers the role of scepticism as the source of contemporary social and political movements such as climate change denial, post-truth politics, and fake news. It also examines the philosophical arguments for a radical form of scepticism, which maintains that knowledge is impossible.