Human beings free will. Although it is certainly marred by concupiscence and circumstances, free will provides the human species with the ability to choose their actions and to make judgments about what ends in life are worthwhile. Perhaps a better word than ‘free will’ might be autonomy. ‘Autonomy’ derives from two Greek roots: ‘αὐτός’—’self’ and ‘νόμος’—’law’. An autonomous agent is therefore one capable of choosing his own laws, his own rules. (I can thank James Caton for making this point to me.) Across our daily lives, we can see choose different rules for themselves and, very frequently, we can infer their behavior from what kind of rules they have chosen.
Human beings are autonomous. They can therefore choose their own rules. For this reason, it is imperative that we choose them wisely and prudently. Casuistry provides a method for human reason, which like human will we must remember is marred by concupiscence and circumstances, to formulate abstract rules that can be applied to particular cases. A principle that should inform all casuistic reasoning is that rules should first be able to decide easy cases before they are applied to harder cases. The reason for this is twofold: 1) Easy cases are those scenarios that define daily life and we should first know what to do in ordinary circumstances before we can think about extraordinary cases; and 2) Moral reasoning needs the principles first decided in the easy cases in order to properly decide the hard ones. A casuistry of easy cases is therefore prior, both in terms of actual life and in terms of the difficulty of reasoning, than a casuistry of hard cases.
The moral rules derived from thinking about hard cases might be adapted to solving those hard cases (though even that much is dubious), but they will not be adapted to giving answers to the more probable issues of human life. Yes, the extraordinary cases may be more visceral and they may therefore enchant the imagination, but the ordinary cases are the problems that populate most of human life. Furthermore, those ordinary cases are more easily decidable. The rules that we formulate from thinking about them are therefore more probable than those that we formulate from thinking about hard cases. Moreover, we often need the rules derived from the former in order to test those derived from the latter. The abuse of casuistry comes from when we neglect the need of disciplining our daily lives with moral rules and instead decide to simply justify our lives with arbitrary rules. When we do not live out our rules in daily life, we are always in danger of fitting our life to a narrative rather than fitting our lives to proper and virtuous rules.
Formulating moral rules based on hard cases first is putting the donkey before the cart. A donkey cannot effectively push a cart, nor can hard cases effectively guide a moral life.