Responsibility and voluntarism
Broadly speaking, human beings tend to correlate, at least intuitively, responsibility and voluntary action. Thus, the most blame is assigned to persons for their actions and the consequences they entail when we have good cause to believe that both:
the action was performed voluntarily and without outside coercion
the agent understood the full range of the consequences of his decisions and actions, as could have reasonably been foreseen either at or prior to the time that the action was performed.
Conversely, there is a tendency to be much more sympathetic to those who satisfy any of the following conditions:
the agent was coerced to perform the action
the agent performed the action through accident and without any fault or negligence of his own
at the time of his actions, the agent did not know, and had no way of knowing, the consequences that his actions would bring
Parenthetically, the above criteria do not correlate exactly with moral praise – while it may be true that one can, and should assign a good deal of moral praise to those who had performed a good action, or an action entailing good consequences, completely on his own volition and uncoerced, it is debatable that the same distinction holds for involuntary actions that happened to turn out well or happened to produce good outcomes.
This correlation between responsibility and voluntary action is acceptable to most people on an intuitive level; indeed, this correlation is echoed in American and European law: for this reason, for example, manslaughter, or killing in self-defense carries a significantly different type of legal punishment (i.e., formalized moral blame) than premeditated murder.