I want to clarify my motive in posting the Witsius quote. I was not trying to argue that Witsius is the same as Kline, or that Witsius decides the question of what the WCF means.
My opening sentences were: “The great 17th century Reformed theologian, Herman Witsius, believed in the doctrine that now goes by the infelicitous name ‘republication.’ He taught that there was a repetition of the Adamic covenant of works in the Mosaic economy ....”
Some may take “republication” as a reference to one particular formulation of republication, namely, Kline’s. But I do not have such a narrow definition. For me, “republication” (or “repetition” to use Witsius’s term) is a broader category that includes Turretin, Witsius, Owen, Petto, Hodge, and many others ... as well as Kline. I distinguish between a doctrine and the way a doctrine is formulated. We all hold to the doctrine of the Trinity, but there are a variety of ways of formulating that doctrine, some more scriptural than others.
So here. Covenant theology is deeply indebted to Paul’s teaching that the Mosaic law contains a works principle (Lev 18:5; Deut 27:26). But there are a variety of ways in which covenant theologians have historically tried to formulate the concept of the works principle in the Mosaic economy. For example, Turretin borrows a page from Aristotle and comes up with the substance vs. accidents formulation: the Mosaic covenant is, as to its substance, an administration of the covenant of grace, but the repetition of the works principle is present in the accidental features, or external economy, of that covenant (see his Institutes of Elenctic Theology, Twelfth Topic, Seventh Question).
Then there is the “subservient covenant” view of Bolton and others. I take Witsius to be either in this camp, or at least similar to it, because he does not see the Mosaic covenant as nothing but a covenant of works, nor as nothing but a covenant of grace, although it presupposes both the covenant of works and the covenant of grace (The Economy of the Covenants, vol. 2, pp. 184-6, in the English translation by Crookshank, printed in 1822), and because he says that the repetition of the Adamic covenant of works is “subservient to the covenant of grace.”
Kline would formulate the works principle differently from all of the above, using his concept of the two layers, with the typological intrusion of the works principle at the top layer.
These are different formulations, but they are genetically similar views, as distinct from those who deny the works principle in the Mosaic economy altogether. Witsius is widely regarded as a reliable, orthodox Reformed theologian. He is not a fringe character. My point in quoting Witsius, then, is to make the point that the republication doctrine (as it is called today) is a major and recognized position in the historical development of covenant theology. Therefore it should not be viewed as heretical or dangerous or as hostile to the Reformed system of doctrine.