How should government act to ensure public awareness of terrorism, while denying terrorists the publicity they seek? What line should be drawn between freedom of information and preservation of necessary state secrets? To what extent if any should legal rights be abridged in the name of national security?
These genuine dilemmas reveal choices with costs and benefits; and, as a rule, all spring from incommensurable values. There is no common metric, no single ruler or measuring rod, on which the values of civil liberty and national security can be directly compared.
The security-conscious may declare that, without security, there would be no civil liberties to enjoy; to which the libertarian may respond that civil liberties embody, and perhaps are, precisely the values we, as a democracy, seek to defend.
