Early in his section on the Law of God in his Institutes of Elenctic Theology, Francis Turretin discusses three views on the question, “Are the precepts of the Decalogue of natural and indispensable right?” He answers, “We affirm.” He briefly describes these three views: the views of Occam, Scotus, and Aquinas. He writes (11.2.10-11):
There are three celebrated opinions: two extreme, asserting the dispensability or indispensability of commands; the third (a middle one) maintaining them to be partly dispensable and partly not.
The first holds that the moral law in its precepts is dispensable; it is founded, namely, on positive right alone, which depends upon the free will of God. This law, therefore, he can change at his pleasure. This opinion is held: (1) by many of the Scholastics (Occam)….These are joined by those of our party who maintain that the moral goodness and wickedness of things flow from no other source than the free will of God; so that things are good and just only because they are commanded, not commanded because they were just antecedently. Thus there is nothing to hinder his commanding the contrary to them if he wishes.
The second the middle opinion maintains that three precepts of the first table are indispensable; that the fourth, however, is partly dispensable; and that all the others of the second table are dispensable (as Scotus and Gabrield [Biel], who therefore take away those precepts from the natural law strictly so called). To them some of our men approach, who maintain that certain moral precepts of the Decalogue which flow absolutely from the nature of God are absolutely indispensable (such as the first, second, third, seventh and ninth), but the others, depending upon the free will of God (as the fourth partly, and the fifth, sixth, eighth and tenth), although immutable and indispensable as to us, still are dispensable as to God (who can for certain reasons command the contrary and yet do nothing repugnant to his own nature).
The third is the opinion of those who hold that the moral law as to all its precepts is simply indispensable because it contains the intrinsic reason of justice and duty; not as proceeding from the law, but as founded on the nature of God and arising from the intrinsic constitution of the thing and the proportion between the object and act, compared with right reason or the rational nature. Thomas Aquinas, with his followers…think thus.
This last is the more common opinion of the [Reformed] orthodox. We also follow it with this limitation however–all precepts are not equally based on the primary right of nature, but some flow absolutely from the nature of God and command such things as God wills most freely indeed but yet necessarily (and so necessarily and immutably that he cannot will the contrary without a contradiction). However, other precepts depend upon the constitution of the nature of things (the free will of God coming in between) so they should not be thought to hold an equal degree of necessity and immutability. Although a dispensability properly so called does not have place in them, still a declaration or interpretation is sometimes given concerning them, the circumstances of the things or person being changed.
Turretin admits that some in the Reformed camp have accepted Occam’s and Scotus’s view, but most Reformed theologians, he says, follow the Thomist view. He follows Thomas as well with a modification that moves toward Scotus but not all the way. He gives reasons for this modified view. In his fourth reason, he uses Thomist language.
The moral law (which is the pattern of God’s image in man) ought to correspond with the eternal and archetypal law in God, since it is its copy and shadow, in which he has manifested his justice and holiness. Hence we cannot conform ourselves to the image of God…except by regulating our lives in accordance with the precepts of this law. So when its observation is enjoined, the voice is frequently heard, “Be ye holy, for I am holy.” Now this law is immutable and perpetual. Therefore the moral law (its ectype) must necessarily also be immutable.
According to Turretin, most Reformed orthodox theologians followed Thomas, not Occam, on the question of divine voluntarism. The position that Calvinists must hold to
Occamist voluntarism is a myth. I suspect, however, that this myth will not die anytime soon, despite the evidence.