I have to disagree here. You are right in general with the fact that people tend to withdraw themselves from responsibility, push their failures onto others or simply won’t admit them at all.
But: Not everything has “nothing to do with circumstances” and not “everything is your fault”.
I would rephrase the whole thing into the following: Even if something is not your fault, it is still your responsibility to decide how to deal with it.
Sometimes things just happen due to circumstances which are out of our control. Therefore it is not our fault. But it is still our responsibility to decide how we are going to respond to these events.
If shit hits the proverbial fan and it is not our fault (because it was caused by external circumstances) we basically have two options:
First, we can say that it is not our fault and therefore not our problem.
Or, second, we can take responsibility for things which are not our fault because we realize it is still our responsibility to decide how we are going to react to them.
If a member of your project group has messed up, causing the whole project to stall it is definitely not your fault — you could not have foreseen it. But it is definitely your responsibility to decide if you are going to help out or simply lean back and say it’s not your fault.
You are responsible. You decide.
Other than that, great stuff as usual!