The beheading of a teacher by an 18-year-old outside Paris struck a particularly jarring blow to the French psyche. Samuel Paty was murdered for teaching his students, including young Muslims, about freedom of speech, including the freedom to mock religion. His killing was seen by some as an attack on France’s secular values. Stephen Sackur speaks to Dominique Schnapper, president of a council which advises the government on secularism in education. Is France's government getting its response to this tragedy right?