You all post spiffy topics within your concentration of study, so I will do the same. Unfortunately, there is a severe misunderstanding that management is easy - when studied right, it is quite rewarding and challenging.

Should managers be held accountable for workplace violence? I expect you to put your best effort into this one.

I believe that workplace violence nine times out of ten results in a slippery slope. It is the manager's duty to *manage* their employees, and therefore they should make it their business to observe interpersonal communication and interactions among employees. Workplace homicide, when not contemplated, is regrettably out of the manager's control...however, reacting to the situation in a timely matter should be a requirement not just a suggestion.

I would never go so far as to say that one individual should be held responsible for another individuals actions.
Workplace violence most often hinders efficiency. If there are not attempts to correct for inefficient actions of employees than the business as a whole suffers. Thus, it is definitely in the best interest of the manager to correct workplace violence, but it is not his fault.

In some cases, work efficiency is improved by violence, such as in the case of an overseer with a whip. I cannot see when this occurrence would occur without a decision from management though, and therefor the manager is responsible in such a case.

And of course if the manager is violent, he is responsible.

Obviously, when considering the high-flown philosophical sense of 'responsibility for the actions of another person', you are right - the manager is not the one to blame. But from the point of view of the chain of command, he should've removed the violent individuals as soon as possible from the team.

But how can the manager know when simmering discontent will turn into violence? A worker could have pent-up rage for years, never show it, and one day just burst out at the last straw. Also, economically, as long as the angry worker fulfills his assignments, the manager may not see the need to hire and train a new individual.