I think it's quite credible that Merah did act alone. He may well style himself as an 'Al-Qaeda' fighter. Pretty much anyone can, if they want to. Plus he's Algerian, which means there's possibly a specific dynamic at work concerning his motivations with regard to the shared history of France and Algeria. All of which means that when you look at specifics the story becomes at once more complex and more interesting (if that's the right word).

I don't as yet find it credible that he acted out of mental illness. Personality disorder, perhaps, but that's another phenomenon. Clearly he possessed the capacity to formulate a plan and carry it out just as the IRA, UVF, PLO and all the other highly-motivated terror groups of the past 40-odd years have done (though that doesn't, as I say, preclude him acting alone).

I find the use of the term 'Islamist' interesting. What does that mean? Is it a synonym for Muslim? Is it a term for someone whose whose membership of a religious community motivates them to political action? Does that make Irish nationalists 'Catholicists?' Does that make Catholics suspect because the PIRA and RIRA are or were Catholics?

It's perfectly legitimate to believe in a united Irish republic. It's perfectly legitimate to believe society would benefit from the operation of Sharia law. It's not legitimate to act upon that belief as a terrorist. It's also not legitimate to assume that all those who support those aims are terrorists. That's the dilemma and the complication of living in a liberal, pluralist society. There are always alternatives if that's not the sort of society you want.