Concerning matters of utility, Vico observes that "in themselves," _ex se,_ they are neither good nor bad (_neque turpes neque honestae_) but become so merely through their relation to the moral consciousness ("but their unfairness is baseness, their fairness, honour: _sed earum inaequalitas est turpitudo, acqualitas autem honestas_"). In the empirical science of utility, he defends against Grotius a "prior natural law," _ius naturale prius,_ to which belong self-defence and the procreation and upbringing of children: and this right he connects with the Stoic _ἀδιάφορον._ That it has no moral authority is proved by the fact that the law which follows it in the historical order, the "posterior natural law," _ius naturale posterius,_ defined by Justinian as "that which is established among all men by natural reason and is preserved by all nations alike" (_quod naturalis ratio inter omnes homines constituit et apud omnes gentes per aeque custoditur_), is prior in the order of right, _prius iure,_ overcomes the former when they conflict and sets upon it the seal of immutability. Now, although this first natural law is defined and exemplified in a merely empirical manner, it is surely at bottom nothing but pure law, law not yet moralised.
But it is upon the concept of "certitude" that law as distinct from morality properly, according to Vico, rests. The word certitude is used by him in many senses, neither clearly distinguished nor harmonised nor deduced one from another: though they all as we have seen unite, rather confusedly, in the general idea of the spontaneous as distinguished, from the reflective form of the mind. Certitude in its practical signification implies among other things an opposition to the "truth" of volition, and is, in a word, force as against equity and justice, authority as against reason, mere will as against the moral will. These are distinctions occurring to our own thoughts, rather than stated by Vico, who both distinguishes and fails to distinguish. For instance, he affirms that "certitude proceeds from authority, truth from reason" (_certuni ab auctoritate est, verum a ratione_) and immediately afterwards adds that "it is quite impossible for authority to conflict with reason, for in that case there would be not laws but abortive laws" (_auctoritas cum ratione omnino pugnare non potest, nam ita non leges essent, sed monstra legum_). At any rate, the New Science seems to him, by reason of this treatment of certitude, to contain a philosophy of authority, which, he adds, "is the source of what theological moralists call external justice." That is to say, he connected the concept of certitude with the distinction and terminology of external and internal, already employed by the scholastic morality, which, used about this time by Christianus Thomasius, were destined without any great philosophical merit on his part to give an impetus to the investigation of the philosophical relations between law and morality.