This is an argument concocted for analysis for my Reasoning class.

Because sometimes ordinary people do inexcusable things, we are really far from perfect. Some things ordinary people do are (at best) only excusable on grounds of weakness of will. Why, sometimes people allot themselves the fuller bag of tasty fries, and at least in some of those circumstances those people know full well they ought not do that. And it is pretty clear that that is inexcusable unless it were due to weakness of will. But it turns out, and here is the catch, ordinary people do not suffer from weakness of the will. For we never act contrary to that which we want, all things considered, to do. To see this, you must understand, first that what we think or believe alone is not sufficient to put us into action, but requires for impetus some sort of desire and the desire operative in all practical action is that current desire which is in us the strongest. Now, surely, one’s all-things-considered desire is stronger than any constituent desire you have, since what you want, all things considered, must be a desire that has already taken account the relative strengths of all your other desires, and hence must reflect already that constituent desire which you desire most strongly. Hence, we do do genuinely inexcusable things and so are far from perfect.