Dangerous Ideas is a short (124 pages) study in the history of modern macroeconomics. At its core is John Maynard Keynes' The General Theory of Employment, Interest and Money, arguably the twentieth century's most influential economics text. Keynes' book was a response to the perceived failure of contemporary economic theory - the 'classical' orthodoxy - to explain adequately the high and persistent unemployment that characterised the interwar developed economies. In turn, his General Theory invited, from sympathisers and critics alike, responses that have determined the development of competing macroeconomic ideas up to the present time, and their application to economic policymaking - ideas both powerful and 'dangerous for good or evil.' The contemporary history of the United Kingdom economy provides a context for theoretical developments.