he was commonly thought by everyone as john maynard keynes equal. but later in the '50s and 60s and 70s, he turned to philosophy, to political philosophy. i think that's the big change. it's not that he changed his opinions about what we unfortunately call capitalism. he thought it was a good thing. he thought that socialism is hard to impossible to make work. >> in your book, you write is a great difference between classic liberalism and contemporary and libertarianism. give us the definition of both of those. >> guest: i'm not sure where that came from an in the book because i'm not sure i believe it. i believe there is, a friend of mine calls it liberalism 1.0. the liberalism, voltaire and adam smith, the blessed adam smith, jon stewart mills, who believed they key to a good society, and prosperous society was to let people have a go as the english say. and that persists in modern libertarianism. what is different is that some of these modern libertarians, especially the americans, how can you say, they are somewhat harsh. i called in brotherly,