In lieu of brute force, the terrorist uses fear. For fear is a great weapon. When you are afraid of your fellow passenger and suspect of your neighbor, that is when the terrorist has won. For he has turned society on itself.
A terrorized society is not only decapacitated, but also vulnerable, simply because scared people are easy to manipulate. You will notice that, as a side-effect, power-hungry people will use your fear to gain power. What was once a real threat is now a perpetual bogeyman used to limit your freedom and further sustain your fear.
So how do you fight terrorism? With strength. With cooperation. With self-confidence. With reliance in numbers. The terrorist does not have enough power to cause substantial damage. He can perform acts designed to induce fear, but in reality the probability of getting hurt is extremely small. Believe in that. Secondly: stick together. Don't let fear make you introvert. Talk to your fellow passenger and neighbor. Get to know them. This way, we can make it harder for the terrorist to blend in and simultaneously keep morale up together. Lastly, don't feed the power trolls. Don't give up your freedom for a false sense of security. False security is the business of the mafia, not the government.
Instead give directed power to well-established institutions. Give crime-fighting organizations like the police an appropriate budget for investigating terror-related crime, along with powerful tools to use on suspects. But only when there is reasonable suspicion. This is the only method which has been proven effective in catching terrorists, contrary to what some propaganda would like you to believe.
Don't approve of blanket searches. Don't accept "generous" interpretations of your constitution. Don't give the government power to read your mail, e-mail and social network posts. Or to film you on every street corner. Don't relinquish power to organizations which answers to no-one but themselves. Please think about what these systems will degenerate into.
Let us not buy into the war-inspired territorial thinking as a mechanism of security. Isolationism is dangerous. Just look at the nationalism and isolationism prior to the world wars. Do we really want to revert the globalization which the last decades of information sharing has brought about?
Please fight this threat while maintaining integrity. This is a fight for our right to keep our democratic principles. So let's not abandon them in the heat of the moment. For if we do, we are playing right into the hands of the terrorist.