Liberty and security stand in a dialectical relation to each other in that (i) each requires the other to be what it is, and yet (ii) each is opposed to the other. Let me explain.
Ad (i). LIberty is something worth having. But a liberty worth having is a liberty capable of being exercised fruitfully and often. Liberty in this concrete sense requires security to be what it is. My liberty to leave my house at any time of the day or night would be worth little or nothing if I were to be mugged every time I stepped over the threshold. On the other hand, a security worth having is a security that makes possible the exercise of as much liberty as is consistent with the liberty of all. The security of a prison or of a police state is not a security worth having. A security worth having, therefore, requires liberty to be what it is, something worth having.
Ad (ii). Nevertheless, liberty and security oppose each other. The security of all requires limitations on the liberty of each. For if the liberty of each were allowed untrammelled expression, no one would be secure in his life and property. Thus security opposes and limits liberty. Equally, liberty opposes and limits security. The right to keep and bear arms, for example, poses a certain threat to security, as everyone must admit whether liberal, conservative, or libertarian. The question is not whether it poses a threat, but whether the threat it poses is acceptable given the desirability of the liberty it allows.
Ad (i) + (ii). The situation is complex. Liberty requires the very security that it limits, just as security limits the very liberty that it requires. It follows that any attack on our security is also an attack on our liberty. It seems to me that this is a point that liberals and leftists do not sufficiently appreciate, and that some of them do not appreciate at all. The 9/11 attack on the Trade Towers and the Pentagon did not merely destroy the security of those working in them, it also destroyed their liberty, while impeding to greater and lesser degrees the liberty of all the rest of us. But it must also be said that any restriction on our liberties also negatively affects the value of our security -- a point conservatives need to bear in mind.
In the present circumstances, however, when the threats to our security are grave indeed, it is reasonable to tolerate greater than usual restrictions on our liberty. Any liberal or leftist who
disagrees with this should be unceremoniously confronted with the question: How much liberty did the victims of the 9/11 attack enjoy while they were being crushed under girders, burned alive, or falling to their deaths?
I now hand off to Charles Krauthammer, The 9/11 'Overreaction'?