What does Genesis 6:11 mean?

This chapter frequently repeats the reasons for God sending the flood. Verse 5 explained that man, on the whole, thought of nothing but evil. Here, the same idea is brought out again. God sees the earth as it is: corrupt and ruined. What He had made and observed as good in Genesis 1 He now sees as unacceptably disgraced by human sin. A primary evidence of the corruption of the earth was violence. Instead of being filled with good, the earth was filled with human violence to others.

The Hebrew word translated "violence" here is hā'mās'. This implies more than just the kind of brute force attacks we think of when we hear the English word. This can also include injustice, oppression, and cruelty. The term also suggests the effects physical violence has on a person or group which has been violently conquered: oppression, deprivation, and misuse. Men of the pre-flood world are not only disobedient to God, they are harsh and abusive to each other.