At about page 118, Dennett launches into an extended discussion of how we might determine whether or not it would be fair and accurate to say that someone is "responsible" for something happening, and Dennett mobilizes the equation style of discussing statements, coupled with graphs made at various different scales, to carry his inquiry forward. On page 124, back to just plain words (which I like better), Dennett quotes the philosopher William James:
"If a 'free' act be a sheer novelty that comes not from me, the previous me, but ex nihilo, and simply tacks itself on to me, how can I, the previous I, be responsible?"The inquiry, common to both James and Dennett, is framed in the context of causation. How can I be "responsible" if I don't, myself, cause the event being discussed? Well, while it may not be "etymology," strictly speaking, there is another way of trying to talk about "responsibility," that takes the word itself as the focus.
"Responsibility" is a concept named by a "compound" word, composed of these two predecessor words: "response" and "ability."
"Responsibility" could be seen not in the frame of "causation," but in the frame of an "ability to respond," i.e. in a context in which the whole idea of "responsibility" is understood as being something "attributed," not "caused."
That reading of the word removes the concept of "responsibility" from the "scientific" world in which natural laws of causation are applicable, and places the word in the human world of human judgment, in which we decide if it's fair and reasonable to make someone responsible for an event by attributing responsibility according to the rules we deem just.
'Responsibility" is, in fact, a "courtroom concept," derived from the world where we make the laws.