Communication Ethics book part for Observation Two: The ``Sender'' is Always On Top. (This is an automatically generated summary to avoid having huge posts on this page. Click through to read this post.)
in Communication Ethics
The way I'm drawing these diagrams, the sender is always on top. Why is that? Because of the dynamism of messages, as demonstrated by annotation and composition and all of that other stuff we see in the real world, it is obvious that no matter what concrete parts go into making up the message, the person who has the final say has full control over the message; they choose whether to bring two things together, or mask something out, or replace this with that, or what have you. That entity has the power, and therefore the responsibility, of being the sender.
The complementary statement is also true, effectively by definition. The entity that has the final power to change the message is the one that belongs on top, as near the receiver as possible. Of all the entities who may be involved in a given message, that is that one, the only one that makes sense to represent as interacting with the receiver.
This is why earlier when I modelled this essay as a real published book, it is the publisher who is the sender. Intuitively, it may seem like the author is the sender, but it is not the author who has final authority over what is in the book. It is the publisher, who has contracted with the author for the rights to use the book in the publisher's complete message, which will include the text of the book itself, but also additional content, such as a cover and advertisements in the back. If the publisher decides to simply not print pages 26 and 27, then the author can not truly stop them. Thus, it only makes sense to call the publisher the sender; they enjoy privileges that no other entity does, or even can. Being a sender is a meaningful privilege and responsibility.
In summation, an entity is the sender of exactly that content which they can change and nobody else can override that change. Any other definition of sender will result in situations where the putative "sender" is responsible for something they can't change, or situations where the sender can change things they are not responsible for, both ethically repugnant.