Who did this? The Cult of Agency
If one were to apply to everyday life the principles of interpretation of narratives implied by Foucault's and Derrida's notions of author or author function in literary criticism, one would cease to be interested in who committed the murder or who stole The Scream or who caused the fire, or who cooked the delicious omelet we had for breakfast. There would be no giving of credit where credit was due or assigning of blame. The burning question would be, what is the most interesting account of events that can be extracted from this body found on the steps leading into the Sydney Opera House.
The urge to know who did some thing does not reflect a mere desire for closure--if we answer the question we can move on to the next question--as if all aspects of life were an exam paper set before us to pin down exact knowledge gained from study or to provide an argument supporting a lesson from experience.
The desire to know the answer to the question who did this? is a need, not a just a desire, because without that answer it is impossible to understand what was meant by the narrative in question. It is not difficult and not impossible to come up, from imagination, with scenarios that would explain the narrative. That, in fact, is easy. The difficulty is coming up with an explanation that corresponds to all the information that can be gleaned about the event and thereby stands a chance of grasping what meant by the speaker/writer. And knowing who did this is an important aspect of every narrative, even if that answer is, the person who did this wishes to remain anonymous. The real obstacle that frustrates one's search for an understanding is the inability to know who did this, or, worse, the false identification of the agent involved.
It is, of course, true that finding out who murdered the person whose body was found on the Opera House steps will not revive the corpse. Nor will apprehending and punishing the perpetrator restore order and assuage sorrow among those who knew the victim. Nor will it prevent any further acts of violence by others. At least, it never has.
But it is true that identifying the agent of any action puts that action in relationship to a context and history that forces us to account for the action in a particular way. Whether the action is a murder or an act of kindness, whether it was a typo or an emendation in a text, the identity of the person who did the act helps us assess the value or damage done. For some, if the death was caused by lethal injection under the eyes of the law exacting its pound of flesh from a criminal, that circumstance makes the murder okay--for some. For some, if that alteration in the text was made by the publisher's editor in an attempt to improve the marketability of an author's work, the change has a standing that it does not have if the change was introduced by a careless compositor who, in haste, misread the copy or tried to remember too long a phrase when setting type.
In life and in textual studies, one cannot always tell or figure out who did this. One might be cast back upon circumstantial evidence, which is never conclusive, or be tempted to make guesses based on past experiences or expected patterns of behavior, which is just speculation, though the speculators always say their judgments are "informed". We must admit "I was not there" and so our attempts to determine who did this are constructions (I deliberately avoid saying REconstructions) of plausible scenarios. For a vast majority of narratives in life, including textual studies, we know beyond doubt who did it. We recognize the hand writing. The change was initialed. For another tranche of actions we can narrow down the possibilities such that, while there can be doubt, there is usually no difference of opinion among those who have studied the case. Nevertheless, doubt remains. And for other actions we know that something happened, but we have no evidence tilting the scales of probability in favor of one actor over another.
When we are reasonably sure of the actor, we have a door opened to us to interpret the act in the light of agency. When we do not know, we must consider the differences that would result depending on who the actor was.