In Albert Camus' book *The Stranger*, Meursault kills a character known as "the Arab" for no real reason at all. Meursault even acknowledges that he doesn't have to kill "the Arab" 

> 
> It struck me that all I had to do was to turn, walk away, and think no
>  more about it.
> 
> 
> 

When he does shoot "the Arab", he notes that "each successive shot was another loud, fateful rap on the door of my undoing." 

All in all, killing "the Arab" seems like a bad idea. But strangely enough, no real explanation is given for why Meursault killed "the Arab".

What's going on here?