When is an idea so objectionable that we should be stopped from expressing it or hearing it? That's the question at the heart of the debate about how Mohammed Emwazi turned from a quiet and hardworking schoolboy into a psychopathic murderer. The focus has been turned on his time at the Westminster University and the extremist preachers who had been invited to talk there. The government is in the process of drawing up guidance for vice chancellors as part of a new statutory requirement on universities to combat radicalisation on campus. Some universities have been accused of being too liberal and ignoring the damage that can be done to vulnerable people by those who promulgate extremist views. Others argue that especially in universities you must and should be able to debate ideas freely, rather than simply banning those who believe them. There are many examples of thought, knowledge or imagination being criminalised. They include: cartoon images of child abuse; the arrests of street preachers; this week's proposal to turn a moral duty to report suspicions of child abuse into a legal duty; so-called predictive policing, which takes incident reports and turns out a computer analysis of where crimes are most likely to occur and who might be the likely perpetrators. Are we living in more censorious times or is this a recognition that to be truly virtuous we need to possess mens sana in corpore sano? Is it simply a matter of distinguishing clearly between thoughts and deeds? Can our thoughts, ideas and imagination live in a world beyond notions of right and wrong and consequences? Or can thoughts be immoral irrespective of whether they're associated with actions? The moral maze this week: the morality of the imagination and the public sphere.