Freedom and Schengen

With the latest terrorist attack in France people are trying to reduce the liberalization of Europe. Under attack now is the Schengen treaty with xenophobes calling to close the border. The issue is that there have been very few terrorist attacks in Europe relative to other countries is still very low, and his won't stop them. Even with massive surveillance no country has succeeded in stopping a single terrorist attack through such methods, and without that information all closing the borders will only waste money and hurt the economy. The United States has the NSA of course, and there is no evidence that surveillance has ever been necessary to stop a terrorist attack.
https://www.newamerica.org/international-security/do-nsas-bulk-surveillance-programs-stop-terrorists/

I do not think closing the border will make any significant difference regarding terrorist attacks. There were attacks before open borders, and there are still attacks. All it will do is isolate Europeans from each other and inconvenience travellers.

To fight terrorism, the only thing we can do is reach out to people at risk of these groups. Increasing communication and trust between peoples through travel, internet, and friendship will help tear down dictators and expand liberty. Closing the borders only plays into their hands by doing the opposite.