For politicians, it’s a real quandary. An exceptionally sharp dilemma in a generally tricky business.
Put yourself in the place of our politicians. Say you’re a front bench spokesperson. You want to condemn terrorism without equivocation. It is criminal, abhorrent, utterly wrong. Yet at the same time you may want to spotlight - and seek to alter - circumstances in which you believe such terrorism might thrive.
How do you do that, how do you highlight the culture, the soil in which terrorism exists without appearing, to some degree, to exculpate the acts of terror themselves?
In the Commons this afternoon, Nick Clegg of the Liberal Democrats tiptoed towards this quandary. He argued that, while we condemn terrorism without reservation, we should also recognise the grievances that exist in the wider Islamic community. Those might include Iraq and the conduct of Middle East policy.
Let me stress - as Mr Clegg did - that he was in no way condoning those who targeted Glasgow Airport or the London night club. Rather he was arguing that it is naïve to consider the extremist reponses without also considering the political circumstances in which such responses may develop.
It had been an occasion of unity. The new Home Secretary Jacqui Smith was warmly praised on all sides for her steadfast and calm response to events. She told MPs that Britain would not be intimidated by terror.
And, in response to Angus Robertson of the Scottish National Party, she extolled the value of the co-operation she had received from the SNP executive, mentioning Alex Salmond and Kenny MacAskill.
In an impressive contribution, David Davies of the Conservatives endorsed the efforts of the police, the security services - and the public, including the civilians who intervened to help officers at Glasgow Airport. He said: “A real hero is someone who runs towards danger whilst others run away.”
To repeat, Mr Clegg did not depart from this united approach. Indeed, he nodded vigorously when the home secretary intepreted his remarks as seeking to isolate extremists from the wider, law-abiding Muslim community.
But perhaps he raised an intriguing political - and philosophical - point.