There have been a lot of different theories about why homicide and crime rates go up and down with a little agreement. The issue is that criminals decide on an individual basis to commit violent crimes and we are trying from aggregate level data to go back to figure out what individual criminals are doing. Part of the reason that the media focuses on guns so much is that A) they have a predisposed idea that guns are bad, B) it helps cover up unpleasant facts in today's society.
I am just going to focus on one massive driver of homicide and violent crime statistics.
First, large cities have a violent crime problem and much of that problem is related to buying and selling drugs, struggles among dope dealers, and the temptation by users to acquire the drugs by illegal actions. In some cities, this has led to political corruption, e.g. Chicago, where gangs have affiliated themselves with politicians. Not a new thing, the old political machines used to do this as well.
Second, gangs have served as an alternative family for a lot of young males and replaced any real home life and values that these individuals might have developed. Like it or not, nuclear family disintegration has effectively removed positive influences such as working, getting a job, etc. with street values of predators and prey. Gangs particularly target young teenagers below 18 for bad deeds because of lighter sentences given to these individuals. The young teens in turn look up to the older gang members for acceptance. The cost of acceptance is do the dirty work the surviving old gang members, not in prison or dead, survived doing. The rules, stability, sense of place in society, are all internal within a gang and they look at outside society as prey and irrelevant to their world. The situation has created mass numbers of sociopaths. The collapse of most inner city schools and discipline within those schools hasn't helped nor have the social workers as a whole. The overall lack of suitable blue collar jobs in inner cities, ironically in part because of crime and uneducated workforce, has made matters even worse.
Increasing ethnic conflict among gangs is also something that makes it worse. Most lower rung jobs in cities, what ones there are, have went to new immigrants, illegal or legal. Employers justifiably argue that they work hard, stay of trouble, work cheap, are willing to do dangerous, off the books, jobs etc. Many immigrant small businesses also practice nepotism in hiring. However, effectively they have locked existing low income residents out of those jobs.
If you effectively deal with inner city crime, you will eliminate a lot of the homicides occurring. We know what the problem is, the issue is no one is accept some pretty strong medicine to get there that effectively the voting public in such places or even states will not accept to resolve it.
So, politicians simply take the easy way out--why not simply blame firearms for the violent crimes. And when those are gone, blame knives and acid or illegal importation of firearms as England has done, and then blame drinking, drugs, etc. and try to stamp those out. The public simply wants something done and is relatively ignorant of what has to occur when the underlying problem of violent crime has multiple causes and unpopular effective solutions. Eventually, if society gets bad enough criminals, they will simply move to eradicate criminals themselves--see the Philippines for example.
