The idea that a machine could exhibit the moral and emotional complexity of a human seems laughable -- at least right now. Our relationship to computers as tools has conditioned us to view remote-piloted drones and fully autonomous drones as two distinct phenomena. But perhaps there's really less of a divide there than we think. What if this is simply the constructed product of our biases talking? In fact, both technically and ethically, fully autonomous drones may not be that different from the ones we use now.

* * *

Suppose that a thinking robot follows all the appropriate laws of war. Human Rights Watch's Tom Malinowski describes the problem this way:

The robot, in other words, might reach the same "legal" conclusion in such a scenario as a JAG officer. But let's remember: proportionality decisions require weighing the relative value of a human life. Would we be comfortable letting robots do that? How would we feel if someone we loved were killed in a military strike, and we were informed that a computer, rather than a person, decided that their loss was proportionate to the value of a military target?

Implicit in Malinowski's last question there is a premise: a family whose son was killed by an unsupervised drone ought to be more upset than if they'd found out he'd been killed by another human being.

On its face, this makes perfect sense. It wouldn't be fair any other way; it would've been a cheap shot, otherwise. Yet the history of combat is literally the tale of one cheap shot after another. From the bow to the longbow, the rifle to the sniper rifle, the hot-air balloon to the jet fighter, military tacticians have been obsessed with increasing the range of their weaponry. Killing more of the enemy from afar weakens his resolve while preserving your own resources.

That we've been on an everlasting quest for the ultimate ranged weapon doesn't necessarily make it the universal solution. One unfortunate consequence of the high-tech style of war pioneered by Donald Rumsfeld, the former U.S. defense secretary, was that troops operating off the battlefield couldn't relate face-to-face with Afghans and Iraqis, which was precisely the wrong strategy in what ultimately became a war for public opinion.

But in the same way that obviously unfair technologies like camouflage and submarines eventually became commonplace (the historian Michael L. Hadley writes that subs were initially regarded as "at best ungallant devices, at worst profoundly evil"), the transition to fully autonomous drones may be unstoppable. The tactical advantages are just too tempting. Not that it would matter to the hypothetical family whose son our drones just killed.

And this is precisely the point. The range at which this family's son was killed would probably matter less in the days following than that their son was killed at all, to say nothing of whether the weapons platform was manned, unmanned, or totally autonomous. Chances are, they wouldn't even know.

* * *

If it becomes impossible to tell whether a robot or a human dealt the killing blow, the boundary between the two begins to break down, and the stumbling block over drones turns from whether letting a computer take the shot is okay to why we feel uncomfortable doing so.