While I certainly have not developed this theory to an exegesis level and it's not perfect, the more I think about it (especially in relation to issues with others that hurt, irritate, or anger me), the more I like it. I consider myself a decent person, thanks to fantastic parents who taught me about valuing others, even if I dislike them. In no way am I perfect in this area (or ANY area, for that matter), but I still consider myself to be a decent person who attempts to live with values such as thoughtfulness and consideration for others.
Inconsideration has many facets; selfishness, egotisticalness (ok, not a real word, but you know what I mean), etc, etc. More often than not, people hurt each other because of inconsiderate behaviour, which ranges from pollution (inconsideration towards the environment), vandalism (inconsideration towards strangers) and simple thoughtlessness to far worse (inconsideration towards friends). Often acts of inconsideration lead to other problems: rifts in relationships, unforgiveness.... I could go on, but I'm lazy and after working in Korea as an English teacher for over two years, I now lack the vocabulary.
There are many examples I could give, but I'm sure you've got the idea. Think of anytime someone's behaviour has hurt you, and I'm sure at least 95% of the time it can be attributed to inconsideration.
Why can't people just be decent?