There are chances that you might have come across a situation where nobody is at fault but still you need to identify someone who can be held responsible for certain incident. This happens especially in big events, both in social set-ups and professional organisations. Some mistake might have happened but it turns out that no one in particular is answerable for it. No one in responsible position was expected to perform certain acts and ommission of which has lead to the episode in question, or that the particular task was not allocated at all to anyone. But if explanation is asked for, who can be blamed in such a situation?
More often people try to put blame on others in an attempt to clear oneself out. After all, who likes to take the blame? People immediately point a finger at other individuals. While some members of the group might simply try to exonerate themselves of all liabilities, others might go a step forward to fix it somewhere else. A few might even do back-stabbing to punish someone else, specific or in general. If confidential opinions are taken then someone may even blame a certain specific soul who they don't like. In open discussion, a group of people my make a cartel to help each other so the left outs have to share the blame. Different ways, but all aimed at not taking the blame, not finding the actual reasons, just to absolve ownself from any liability.
Imagine how difficult it is for the head of any organisation to actually find out who is responsible for the fault. Can he be objectively clear to apportion proportionate liability for the mistakes? Some management gurus would say that the true leader would take the blame on himself. That is totally fine, because the leader is always answerable for the faults and limitations of his team. But that doesn't resolve the problem. The true leader should also be able to identify the portion of error and oversight which have played a role in creation of such predicament. There is a particular type of bosses who would be very quick to put blame on one person whom s/he doesn't like. Any such incident gives her/him a much desired opportunity to guillotine the detested people from organisation. This approach is also evidently faulty, rather conspiratorial.
Ever in future if you have to decide in such contingency, better to work towards finding out actual blunder, and fix it. Proportionating it is also a good way, but simply acquitting ownself or cartelling or conspiring to fix it on others is never a productive way for anyone.