The justification for allowing robots to wield weapons is simple: Humans are terrible at making decisions. Anything we fear killer robots might be capable of doing (short of the actual robot apocalypse) is something we humans already do to one another. Human soldiers become tired, inattentive, confused, uncertain, angry — all of which can lead to mistakes, including the killing of innocent civilians. AI may still pale in comparison to humans when it comes to distinguishing real threats from imagined ones, but it’s just a matter of time before it catches up.
But what about gut-instincts? What about those emotional hunches that help flesh-and-blood humans make calculated decisions? They’re little more than the product of being able to integrate our knowledge and prior experiences with all the data our senses are delivering to us at a given moment. When a soldier sees someone walking down the street with a lump under his jacket, he’s processing all the available information to make a judgment about whether or not the man is a threat. In the not-so-distant future, robots will be able to process all that information far more effectively than humans in the vast majority of situations. Plus, they won’t get tired or scared or angry. When robots reach that point, not employing autonomous weapons systems will mean sacrificing the lives of civilians (and soldiers).