Imagine a mother who sees her children playing with toy guns as a military force approaches their village. Terrified, she sprints toward the scene, yelling at them to hurry home. A human soldier would recognize her fear and realize that her actions are harmless. A robot, unable to understand human intentions, would observe only figures, guns, and rapid movement. While the human soldier would probably hold fire, the robot might shoot the woman and her children.
Despite such obvious risks to civilians, militaries are already planning for a day when sentry robots stand guard at borders, ready to identify intruders and to kill them, without an order from a human soldier. Unmanned aircraft, controlled only by pre-programmed algorithms, might carry up to 4,500 pounds of bombs that they could drop without real time authorization from commanders.
While fully autonomous robot weapons don't exist yet, precursors have been deployed or are in development stages. So far, these precursors still rely on human decision making, but experts expect them to be able to choose targets and fire without human intervention within 20 to 30 years. Crude models could potentially be available much sooner. If the move toward increased weapons autonomy continues, images of war from science fiction could become more science than fiction.
Replacing human soldiers with "killer robots" might save military lives, but at the cost of making war even more deadly for civilians. To preempt this situation, governments should adopt an international prohibition on the development, production, and use of fully autonomous weapons. These weapons should be stopped before they appear in national arsenals and in combat.
Fully autonomous weapons would be unable to comply with the basic principles of international humanitarian law -- distinction, proportionality, and military necessity -- because they would lack human qualities and judgment.
Distinguishing between combatant and noncombatant, a cornerstone of international humanitarian law, has already become increasingly difficult in wars in which insurgents blend in with the civilian population. In the absence of uniforms or clear battle lines, the only way to determine a person's intentions is to interpret his or her conduct, making human judgment all the more important.
Killer robots also promise to remove another safeguard for civilians: human emotion. While proponents contend that fully autonomous weapons would be less likely to commit atrocities because fear and anger wouldn't drive their actions, emotions are actually a powerful check on the killing of civilians. Human soldiers can show compassion for other humans. Robots can't. In fact, from the perspective of a dictator, fully autonomous weapons would be the perfect tool of repression, removing the possibility that human soldiers might rebel if ordered to fire on their own people. Rather than irrational influences and obstacles to reason, emotions can be central to restraint in war.