While at a low, practical level, tastes are subjective, what is ultimately beneficial for a man is determined neither by choice nor by accident, but is immutably determined by the nature of creation (the concept of “rightly understood interests” to which some praxeologists refer, that people’s interests are not necessarily what they sincerely desire). What is ultimately desirable in this manner is called “good”.1 However, only rarely can action reach such an ultimate good directly; more often, approach to the ultimate good requires many intermediate steps, which may also be called good by imputation from their object.
Furthermore, causes are attached to effects.2 While many actions (voluntary causations) produce proximate effects that are of no intrinsic desirability, the desirability of their ultimate effects depending on external circumstance, certain actions, even though the specific net state change effected may vary with circumstance, are invariant in the desirability of that change; these actions may be termed absolutely good or bad, depending on the nature of their effects.3
Thus arises a natural law for human behaviour: certain actions are contrary to nature and will always bring harm upon the actor.4 This natural law is not extraneous to creation but an integral part of it, a direct consequence of causality and the existence of universally desirable ends.
This natural law must be differentiated from divine law both in nature and in consequence. Natural law is a property of creation, incapable of change without a change to the created order, with its punishments similarly innate to cause and effect. Divine law, on the other hand, is extraneous to creation, revealed directly by God, and with its punishments accomplished in this world by divine intervention (which need not, of course, be immediate). The two are in consonance, for the creator who commands what he has ordained to be harmful in his creation would be truly perverse (or, from the other perspective, who would arrange creation to punish what he commands). The two need not, however, be coextensive; revealed law may command what is not commanded by natural law, but will not command what is forbidden by it.
The clearest application of the natural law is to individual behaviour; once an action has been determined to be contrary to the natural law, it may be avoided with no need to rederive the harm produced. But natural law seems to have found its greatest influence in legal theory; its application there is murkier. Clearly, a legal system not in consonance with natural law cannot, from the definition of natural law, be beneficial; the same also applies to laws. But consonance with natural law does not (at least directly) imply that laws ought to add to the punishments prescribed by the natural law, for it is in no need of assistance in that respect. Instead, it means that the enforcement of the laws must not involve a violation of the natural law by any party. What this specifically means for government I shall address in a later post.
1 “Good” is predicated of actions, objects, and people in analogous ways; strictly speaking, it refers to a gross state. Attributed to an action, “good” means that the action will result in a better state than the present (but not, it must be noted, necessarily better than all possible states of affairs, for which reason what is good in itself may not be good in a specific instance); attributed to an object, that possession of the use of that object would result in a better state; attributed to a person, that the person does what is good. God is good in both of the latter senses; association with him is desirable and he does what is desirable (the latter being a simple deduction from his omnipotence and omniscience).
2 For the purposes of this discussion, I divide effects into proximate effects, which necessarily and immediately arise without dependence on circumstance not assumed by the action, and ultimate effects, the net state change resulting from the action. Between those extremes is a spectrum of mediate effect.
3 This is a specific case of the general principle of action that certain means are inappropriate to achieve certain effects (such as that price controls are an inappropriate means to achieve the reduction of a shortage); to be termed good or bad, an action must be inappropriate not for one specific ultimate effect, but for all bad or good effects, respectively.
4 Natural law is descriptive, like all other laws, but it describes effects, not behaviour. Many people have commented that it is possible to violate natural laws, albeit with penalty, while it is impossible to violate physical laws; this misstates the point. The actual law is the penalty, not the prohibition.