The major argument in favor of gun control typically consists of three parts. First, proponents of gun control argue that gun violence is a serious problem in the United States. Second, they argue that reducing the number of guns (or the number of some types of guns and ammunition clips) would reduce the severity of the gun violence problem. Finally, they argue that gun control would not be a serious infringement on people’s rights.
The first part of this argument is relatively easy to make. The United States has much higher rates of gun violence than any rich country in the world. This is not open to debate. What is harder is the second part of the argument. Gun control advocates argue that restrictions on guns would make it harder for people to use guns to kill and would therefore reduce the murder rate in the US. They argue that a ban on semi-automatic weapons or on high-capacity ammunition clips would prevent people from engaging in mass shootings like the recent one in Connecticut. People would still have the capacity to kill others, but it would be much harder if the people did not have guns or if the guns were less able to fire so rapidly.
Finally, gun control advocates argue that people would still have the right to bear arms that is guaranteed to them by the Constitution. They would still be able to have guns for hunting and (at least to some gun control advocates) for defending their homes against intruders. What they would not have is weapons that could kill so easily.
There are, of course, many other arguments and many variations of these arguments. However, this is the basic outline of common arguments in favor of gun control.