When we are dealing with items that have precise boundaries and are subject to the control of the owners, we are dealing in the moral area. This gives us a concept where precision can appear. We know absolutely how far our property rights go. They go up to the boundaries of what we own, and thus control. They do not go beyond. So when we find ourselves in an area where the property (moral) rules cannot be invoked, for one reason or another, we fall into the area of manners. Good manners are a substitute for moral boundaries where the latter cannot be determined.
Let us suppose, for example, that a man enjoys eating onions. He purchases them and he eats them. This man wishes to go out with a woman who becomes ill if she has to smell onions. The man has a right to eat the onions. The woman has a right not to smell. How do we get around that dilemma?
The question of the boundary of the onion odor is a problem we have not as yet solved, at least within a moral context. We cannot say that the man has a right to inflict an unpleasant odor on the woman. We cannot say that the lady has a right to prevent the man from eating onions. Thus, we are in an area of manners and not of morals.
If it were possible to precisely show the boundary of the onion smell, we might be able to transfer this question into the property area. In this instance, we are lacking as yet in sufficient technology. The extent of the odor is in part determined by the sensitivity of the woman’s olfactory equipment. In theory, the onion odor may extend for many yards. But at various points in space it will no longer be detected, depending upon who is doing the smelling. Nor must we confuse causation of the odor with its boundary. Obviously, it is the man who eats the onions who releases the odor. But the boundary of that odor cannot be determined with accuracy.
So good manners come in to play. The man, knowing that his friend is offended by this odor, doesn’t eat onions if he knows he is to be with her. In other words, he presumes that she has a property right that is determined by a boundary that doesn’t really exist. He presumes that this boundary comes right up to and includes his person, which it doesn’t.
But suppose the man doesn’t know that he is going to be with the woman and has already devoured the onions. Now she appears. It is good manners for her to bear up under the burden and to ignore the odor if she possibly can. In other words, she presumes that he has a property boundary well beyond the range of his person, which of course is not so.
This is all mannerly behavior is. It is the presumption of the existence of a property boundary that cannot be determined; and the presumption is made in favor of the other party.
When we are dealing with property boundaries, we do not have to presume. We know where the boundaries are. We know precisely where we may go without trespassing and where we may not go. Where boundaries are not discernible for any reason, we act as if there were boundaries in existence, and we give the other party the benefit of the doubt.