The Greatest Contribution of a Philosopher?

John stuart mill's views on free speech still live with us to day. I think we are started to forget some of those principles. A lot of the freedoms that we take for granted ar being eroded. There is no such thing as the phenomenology of a group, there's nothing it is like to be black or white and male or female. And so nagel wrote a little article which really changed philosophy - what is it like to be a bat?