he was commonly thought by edwin as john maynard keynes equal. and, but later in the '50s and 60s and 70s, he turned to philosophy, to political philosophy. so i think that's a 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. >> host: in your book, professor, you write that there is a great difference between classic liberalism and contemporary libertarian. give us a definition of both of those. >> guest: i'm not sure where that came from in the book because i'm not sure i believe it. but i believe that there is -- a friend of mine calls it liberalism 1.0. liberalism of voltaire and adam smith, jon stewart mills, who believes that the key to a good society was to let people have a go as the english essay. and that persists in modern libertarianism. what is different is that some of these modern libertarians, especially the americans, how can you say this? they are somewhat harsh. i call them brotherly, wherea