On the battlefield, soldiers try to dehumanize their enemy. If they didn't, many would not be able to fire their weapons.
America's rebels called the British troops "Redcoats." Japanese and German soldiers were called much worse in World War II. So were the communists in Korea and Vietnam.
You can bet our troops in Iraq have derogatory names for the enemy, even though you won't hear them say such words on the nightly news.
Of course, not all battlefields are foreign, nor all "enemies" foreigners. Every day in U.S. cities, wars are being fought to curb urban violence.
The highest casualties are among the young men whose gunplay mostly leaves one another dead or wounded. But sometimes, too many times, an innocent bystander succumbs.
Other times, it is a law enforcement officer who uses deadly force. Often, it is justified. Sometimes it is not. That's why care must be taken to review whether the officer's action was appropriate for the situation.
That an officer may fire hastily because he has dehumanized the "enemy" is not out of the question. But such deadly errors can be avoided through training, guidelines and counseling.
Philadelphia police fatally shot 20 people last year and three in only the first three weeks of this new year. That pace demands a reevaluation of whether officers have the right training, guidelines and counseling.
Police Commissioner Sylvester Johnson says a high number of police shootings are to be expected in a handgun-heavy city where 406 murders occurred in 2006. That may be generally true. But two of the three victims this year don't exactly fit that explanation for police aggressiveness.
Charles Kelly, 26, is believed to have been suffering from a mental illness when he lunged at officers with a knife and was shot Jan. 14 near City Hall. Properly trained officers with the right equipment have been able to subdue individuals in similar situations. A Taser stun gun fired at Kelly apparently had no effect.
Bryan Jones, 20, was fatally shot by police who had responded to complaints of people firing guns into the air to celebrate New Year's Day. Police said an officer shot at Jones after seeing an armed man in an alley, but Jones reportedly was unarmed.
Did officers sent into a dangerous situation too quickly see Jones as the "enemy"? An investigation is ongoing. Information from that probe, including the officer's name and record, should be shared with the public.