Striker's essay ("Origins of the Concept of Natural Law") ends with some puzzling history of philosophy:
[T]he peculiar features of the Stoic theory of nature also prefigure, at least, most of the various other forms that the doctrine of natural law came to assume in the course of its long history. Many of them can be seen as versions of the Stoic doctrine that use just one of the many attributes of nature as conceived by the Stoics. Thus, for example, nature is rational--hence one can claim that the natural law is the law of reason. Nature is also divine--so the Christians could take over the doctrine by supposing that that natural law must be identical with God's commandments. Finally, the contents of Stoic natural law are derived from fundamental tendencies of human nature, and so the natural law could also be represented as a law of human nature--which led to the charge of confusion between descriptive and normative laws raised by the nineteenth-century utilitarians.Is Striker claiming actual influence, or simply a similarity?
At first she seems to claim only a similarity ("prefigures, at least"). But then she speaks about borrowing in the abstract ("one can claim"), and then actual borrowing ("the Christians could take over the doctrine..."), and then borrowing in the abstract once more ("could also be represented as"). It must be confessed, this seems confused. What exactly is the historical influence of the Stoic theory, and the actual dependence of other views upon it?
It's puzzling in particular how the Stoic idea that "nature is divine" could have made it easier for "the Christians" to take over the doctrine--since "the Christians" agreed with "the Jews" that, because nature was created ex nihilo, it is in no sense divine. Or, if Striker means by "nature is divine" merely that the cause of nature is divine, then Christians could presumably have assented to that without any need to borrow from the Stoics. As for whether, apart from Stoic influence, it would have been easy, within a Jewish background, to think of ethical precepts as akin to a Law, although not written, but known 'by nature'--that's easy enough to understand (e.g. o(/tan ga\r e)/qnh ta\ mh\ no/mon e)/xonta fu/sei ta\ tou= no/mou poiw=sen, ou(=toi no/mon mh\ e)/xontej e(autoi=j ei)si\n no/moj: Paul, Rom 2:24).
Likewise, it's unclear why a proponent of natural law would need to suppose that all of nature is rational, or to suppose that it is rational in some distinctive sense attributable to the Stoics (rather than nature's simply being teleological, or under the providence of a rational deity), in order to hold also that, for human beings, the supposed precepts of 'natural law' are also precepts of human practical reason.
In sum: the 'concept of natural law' antedates the Stoics (as we have seen); and nothing distinctively Stoic seems required for the concept. How then are the Stoics its originators?