Homeland, Showtime's series about an al-Qaeda sleeper agent in Congress, is both implausible and addictive. President Barack Obama is a fan. That means he has heard more discussion of the downside of drone strikes in a television drama than he has in the presidential race.
In the foreign-policy debate on October 22, moderator Bob Schieffer, of CBS, asked Mitt Romney about the use of drones. Romney responded: "I support that entirely and feel the President was right to up the usage of that technology, and believe that we should continue to use it to continue to go after the people who represent a threat to this nation and to our friends."
This bouquet in hand, Obama didn't even have to use the word "drone" when his turn came to speak.
Neither side wants to look softer than the other on terrorists. Hence the bipartisan support for the strikes. Liberal groups that might be inclined to protest the policy have been quiet because Obama put it in place. The lack of debate about the US reliance on drones is a shame, because there are both practical and moral objections to it.
A few conservatives have raised one practical concern: killing terrorists is justified, they say, but we need to kill fewer and capture more to gain intelligence. You don't have to support waterboarding, as some of these critics do, to agree with that point.
Another concern, raised by a few liberals, is that the strikes have increased anti-Americanism abroad. (On Homeland, one of them turns an American soldier into a terrorist.) The Pew Research Centre has found strong opposition to drone strikes in almost every country.
The strikes may also be setting a dangerous precedent, goes another argument, because "more than 70 countries now own some type of drone".
But the morality of the policy is what most deserves scrutiny. The tradition of thinking about wartime ethics holds that it is permissible to cause the death of innocent civilians under certain conditions: when the war itself is just, the deaths are unintended and the number of innocents killed is proportional to the good the military action is expected to achieve.
Attacks on terrorists from the air meet the first two criteria even if civilians get killed. Whether they meet the third is harder to determine, largely because we don't have reliable numbers. In January, Obama said: "I want to make sure that people understand actually drones have not caused a huge number of civilian casualties."
A report by the Bureau of Investigative Journalism found hundreds of civilian casualties in Pakistan, including 176 children.
In May, The New York Times reported one possible explanation for the discrepancy in estimates. Obama "in effect counts all military-age males in a strike zone as combatants, according to several administration officials, unless there is explicit intelligence posthumously proving them innocent". In other words, Obama has not found much evidence of civilian casualties because he's not looking for any.
The Times also reported that former senior intelligence officials doubt the administration's public line about low casualties.
The alternatives to drone strikes have costs. Ground operations would also cause civilian casualties and could put American troops at risk. Scaling back the drone strikes risks letting some terrorists go to plot more evil. But the costs of killing, injuring, endangering and terrifying civilians have to be entered into the equation.
Robert George, a professor of politics at Princeton University and a leading social conservative, argues that "considerations of justice to noncombatants" sometimes forbid drone strikes "even if that means grave risks must be endured by our own forces in the prosecution of a war".
If we wouldn't be willing to expose our troops to those risks, then maybe the mission isn't so compelling that it justifies exposing civilians to them either. That's the conclusion that Kurt Volker, the head of the McCain Institute for International Leadership and a former ambassador, has reached. He writes that "a good rule of thumb might be that we should authorise drone strikes only if we would be willing to send in a pilot or soldier to do the job if a drone were not available".
Rules of thumb are probably the best we can hope for on this question, because we need a policy that makes use of drone strikes while drawing the line when the risks to civilians become too high. The danger is that using them is so convenient for policymakers that we will use them too much.
The President's aides told the Times that he is a "student of writings on war by Augustine and Thomas Aquinas" and could be trusted to make the right judgments. His practical definition of combatants as anyone we happened to kill suggests otherwise, although too much of the program is secret to say for sure.
The fact that we have barely debated this issue makes it hard to believe that our political system is getting it right, either.