That a science of human conduct is possible, that what any man may do even in moments of the most sober and careful reflection can be understood and explained, has seemed to many a philosopher to cast doubt upon our common view that any human action can ever be said to be truly free. This book, first published in 1961, looks into crucially important issues that are often ignored in the familiar arguments for and against the possibility of free action. These issues are brought to light and examined in some detail.