A simple rule before getting started: In presenting their arguments, philosophers sometimes appear to go off into far distant islands entirely, and then act as if they have shown something about the case at hand. The mystery evaporates if one keeps in mind the following rule of argument:
- If one argument is precisely analogous to another, in all relevant respects, and the second argument is pretty clearly fishy, then so is the first. Likewise, if one argument is precisely analogous to another, in all relevant respects, and the second argument passes swimmingly, then so must the first.
If the argument at hand is murky, while the one in the distant land crystal clear, then appealing to the latter is a powerful way to make a point. Because the relevance for the case at hand seems obvious, details may be left unstated. Of course you may avoid these conclusions by showing just where the analogies break down.
*Full disclosure: I own a fair amount of Diamond Offshore (DO), but do not plan to purchase more in the next 72 hours.