Battling my way through Sarah Palin's book, Going Rogue, last weekend, I began to wonder how American conservatism had come to this. Ms Palin's book is smug, lightweight, nationalistic, entirely free of original ideas. How has this woman become the darling of the American right? How has she become so popular that some bookmakers make her the favourite to win the Republican party nomination in 2012?

And then I realised – the rot set in with Ronald Reagan.

This might seem an odd conclusion, since President Reagan is a conservative hero who won two presidential elections. But the ideas that are now known as “Reaganism” are, in fact, profoundly subversive of some of the most important conservative values. Traditional conservatives disdain populism and respect knowledge. They believe in balancing the government's books. And they are pragmatists who are suspicious of ideology. Reagan debased all these ideas – and modern American conservatism is still suffering the consequences.