Common sense surely is, a gun that is securely locked away, with the ammunition locked away securely as well, just isn't going to be available in a hurry. A loaded gun that is available in a hurry is a serious danger in a home, and has been proved to be so by a whole series of domestic tragedies over the years.

There is no absolute safety in this world. What you can do is work out the relative dangers, and choose the safer option. The safer option seems to be for householders not to rely on guns to protect themselves.