In those days there was no king in Israel. Everyone did what was right in his own eyes. Judges 17:6
Sounds pretty glorious, doesn't it? No king, do what you want. It's essentially the motto of 21st century America. You are your own god, you determine what is best for you, you determine what is right for you. No one can say otherwise.
It's interesting here that the author uses this phrase as a subtle, yet stinging, rebuke of Israel in the days of the judges. There indeed was no king. Of course this was not, in and of itself, the problem. But the apparent vacuum of human leadership that was created was not addressed as it should have been; namely, by the people turning to God for guidance. Rather, each man, woman, and child simply did what was right in their own eyes. The results for their nation were disastrous.
As they have been for ours.
If there is no fixed standard, no one may instruct me how to treat my neighbor. No one may tell me it is evil to offer my daughter as a burnt sacrifice. No one may say not to take a concubine, or, having taken one, to not turn her over to my enemies for them to rape her. No one is allowed to say don't murder that baby--nor her 26 year old mom, if we're going to be logically consistent. No, each simply does what is right in his own eyes, for there is no standard to appeal to. No God, no True King, and laws will not stand. Not when the primary "good" we are seeking is personal happiness. Or self-fulfillment. Or self-realization. Such goals dehumanize those around us, as they become simply a means to or obstacle between me and my personal fulfillment.
That's a scary world to live in. And we're there.