In A Treatise of Human Nature, David Hume observes that agreements can arise from unspoken habits and repetitions of behavior, without explicit promises. He writes, "Two men, who pull the oars, do it by an agreement or convention, tho' they have never given promises to each other." [Book III, Part II, Section ii, for those of my readers who wish to consult the greatest work of philosophy ever written in the English language.]
Susie and I live in a three story condominium building, the first floor of which is occupied by commercial establishments. In all, there are eight apartments, four on each of the second and third floors. We are in one of the third floor condos. Each morning, two different deliverers drop two copies of the NY TIMES and three of the Wall Street Journal near the back door. [This is the first place I have lived in my entire life where the TIMES is delivered, but that is another story entirely]. As I am an early riser, I see all of these papers when I go out for my morning walk. A while ago, I discovered that the young woman at the end of our hallway is the other TIMES subscriber, and I fell into the habit of bringing up her paper, along with mine, when I came back from my walk, and dropping it in front of her door. Then, a bit later, I noticed that the WSJs have mailing labels, which identified which apartments they go to, so I brought them up as well and dropped them off on the second and third floors.
One morning, I did not go out for a walk [my old legs were aching]. When I finally stepped out of my apartment, there was my NY TIMES at my door. With not a word spoken, my neighhbors and I have collectively fallen into an agreement that the first one up will bring up everyone's paper.
Hume traces the origins of the concepts of property, obligation, and right to just such habitual patterns of reciprocal accommodation and cooperation, thereby setting himself against the social contract tradition then dominant in English langiage political theorizing.
To this day, I have not seen the inside of my neighbors' apartments, nor they mine -- very New York of us, quite unSouthern, in fact. And yet, the very first suggestion of an implicit social contract has sprouted.
Now then, what has this to do with Afghanistan or health care reform? Not a thing.