Terrorism is a tactic in which the primary objective is to produce fear, rather than direct harm. Terrorist attacks are, first and foremost, psychological operations designed to alter behavior amongst the terrorized in a way that the actors believe will serve them.

The 9/11 perpetrators killed about 3,000 people, and did about $13 billion in physical damage to the United States. That’s a lot of harm in absolute terms, but not relative to a nation of 300 million people, with a GDP of almost $15 trillion. It was a massive blow to many families, and to New York City. But to the nation as a whole that level of damage was about as dangerous as a bee sting.You may find that analogy suspect because bee stings are deadly to those with an allergy. But what kills people is not the sting itself. It is their own massive overreaction to an otherwise tiny threat, that fatally disrupts the functional systems of the body. And that is exactly what terrorists hope to trigger—a muscular and reflexive response on the part of the victim-state that advances the perpetrators’ interests far beyond their own capacity to advance them.

The 9/11 attack was symbolic. It was not designed to cripple us economically or militarily, at least not directly. It was designed to provoke a reaction. The reaction cost more than 6,000 American lives in the wars in Iraq and Afghanistan, and more than $3 trillion in U.S. treasure. The reaction also caused the United States to cripple its own Constitution and radicalize the Muslim world with a reign of terror that has killed hundreds of thousands of Iraqi and Afghani civilians.

The return on the terrorists’ investment was spectacular. Assuming the official story is right, then Al Qaeda got $7 million of effect for every dollar it spent on the attack–$7 million, to one. The ratio of harm inflicted on U.S. targets by the 9/11 attacks, to the financial harm the U.S. inflicted on itself reflects the same amplification. For every $1 of damage they did to us, we did $231 to ourselves. For every American that was killed in the attack, we sacrificed more than two on the battlefield. And that is all before we consider the instability we brought to the Middle East, the harm we did to our own freedoms, and the spectacular cost to our reputation abroad.

The lesson, of course, is that above all else a nation should refuse to do what everyone will expect it to do in response to an attack. And if there is a silver lining, it is that one does not need to be sure of the identity or intent of their attackers to respond intelligently.

Terrorists do not engage in terror attacks because they are strong. They engage in these attacks because they are weak. The gruesome spectacle of terrorism is a cost saving measure in which the fears of the victims and onlookers amplify the resources that the terrorists themselves are able to deploy.

Reacting reflexively is inherently self-defeating. If a nation wishes to make itself an unappealing target, then it should get its primordial fears under control.

We are not made safe from terrorists by helicopters, or missiles or boots on the ground. Nor is it drones, torture or digital dragnets that protect us. What makes us as individuals safe from a terror attack is the staggering probability that we will be elsewhere when one occurs. Accepting a tiny chance that we will die at the hands of terrorists is a bargain price for freedom. Reconciling oneself to it is very much like accepting a small chance that one will die on the highway, in exchange for the ability to travel at will.

There is much we do not know, and much we many never know about ISIS and its objectives. We can, however be sure of this: ISIS would like the citizens of the West to surrender their liberties, while lashing out blindly into the dark.

This time, let’s not.

Bret Weinstein is a professor of evolutionary biology at The Evergreen State College in Olympia, Washington