Claims about modality - what is necessary, possible, or impossible - abound in philosophy and go back to Plato. They are also at the heart of contemporary debates in philosophy. But what can we actually know about what is necessary, possible or impossible? This is the first book to provide a thorough introduction to the problem of modal epistemology, examining its main theories and weighing up competing arguments and solutions.

Beginning with essential historical background to the problem it explores the following key topics and debates:

• realism and possible worlds, particularly David Lewis's modal realism and Armstrong's combinatorial theory of possibility
• anti-realism and possible worlds, including fictionalist accounts and conventionalist views about modality
• three main theories of modal epistemology: conceivability, linguistic undersatnding, and counterfactual reasoning
• modalism
• modal scepticism.

Including chapter summaries, annotated further reading and a glossary this book is essential reading for anyone seeking a clear and informative introduction to and assessement of the epistemology of modality.