A few weeks ago, Doug Wilson and Peter Leithart engaged in a debate of sorts on their blogs on the subject of regeneration, which morphed somehow into a debate on natures and substances. Without trying to delve into all the (often elusive) details of what they were up to, Leithart was particularly concerned with maintaining a strong emphasis on the mediation of God's actions through creation, which meant, for him at least, that we needed to be wary of doctrines of "natures" and "substances" which reify creatures over against God. Instead, as he argued in "Do Things Have Natures?", we need to insist that God is always dynamically at work in and through his creatures, which means that if God is a historical God, one who unfolds his will in a drama of creation, fall, and new creation, then "natures" are not fixed quantities, but potentially take on new properties as God uses and transforms them in this drama. One way of looking at this issue is to ask, "What are miracles?" For if God is always dynamically at work in his creation, and doing new things in it, then the miraculous is only relative.
Once put this way, the question seems to largely turn on the doctrine of providence, particularly the sub-headings usually called "preservation" and "concurrence." Preservation, essentially, insists that the Christian God is not a deist God; his creation is always dependent upon his sustaining power, which preserves it in being. Concurrence insists that the Christian God is not a pantheist God; he is always and everywhere at work in his creatures, and yet they have a created integrity of their own which allows them to have a certain fixed identity in vis-a-vis God. In his Reformed Dogmatics, Herman Bavinck offers a wonderfully lucid and balanced treatment of these issues, and a little walk through his text may prove instructive for resolving these thorny issues.
Bavinck first affirms that we must not blur together creation and providence (which is precisely what is at stake, it seems, in asking whether God changes the natures he has created), but at the same time must hold them together very carefully, never attributing "independence" to the created order (which was Leithart's overarching concern):
"The two are so fundamentally distinct that they can be contrasted as labor and rest. At the same time they are so intimately related and bound up with each other that preservation itself can be called 'creating' (Ps. 104:30; 148:5; Isa. 45:7; Amos 4:13). Preservation itself, after all, is also a divine work, , no less great and glorious than creation. . . . Although distinct from his being, it has no independent existence; independence is tantamount to nonexistence. The whole world with everything that is and occurs in it is subject to divine government. . . . Scripture knows no independent creatures; this would be an oxymoron" (RD II:592)
The two dangers, here, he says, are deism and pantheism, as just mentioned. Leithart is certainly leaning heavily against the former danger, and one consequence of this is to tend to blur the distinction between miracle and God's "ordinary" action in creation. Bavinck says that in pantheism, means that "there is no room for miracle, the self-activity of secondary causes, personality, freedom . . ." and over against it, "it was the task of Christian theology to maintain the distinction between creation and preservation, the self-activity of secondary causes, the freedom of personality . . ." (599) If we emphasize so much the immanence of God in creation, if we make everything a "miracle" because it is the direct work of God, then we also thereby make nothing a miracle, because the natural order has no self-activity.
Bavinck defines the relationship of preservation and concurrence: "Preservation tells us that nothing exists, not only no substance, but also no power, no activity, no idea, unless it exists totally from, through, and to God. Concurrence makes known to us the same preservation as an activity such that, far from suspending the existence of creatures, it affirms and maintains it" (605). Both emphases must be maintained. On the one hand,
"God is never idle. He never stands by passively looking on. With divine potency he is always active in both nature and grace. Providence, therefore, is a positive act, not a giving permission to exist but a causing to exist and working from moment to moment. If it consisted merely in a posture of non destruction, it would not be God who upheld things, but things would exist in and by themselves, using power granted at the creation. And this is an absurd notion. A creature is, by definition, of itself a completely dependent being: that which does not exist of itself cannot for a moment exist by itself either." (605)
This side of the question is heavily emphasized in Leithart's post.
On the other hand,
"Creation and providence are not identical. If providence meant a creating anew every moment, creatures would also have to be produced out of nothing every moment. In that case, the continuity, connectedness, and 'order of causes' would be totally lost, and there would be no development or history. All created beings would then exist in appearance only and be devoid of all independence, freedom, and responsibility." (607)
Now, his discussion of concurrence is where things get very interesting. Bavinck argues that we cannot attempt to speak of development within natures, unless we can talk about existent natures in the first place. A determinate creation must precede providence. Otherwise all is mere flux:
"Now providence serves to take the world from its beginning and to lead it to its final goal; it goes into effect immediately after the creation and brings to development all that was given in that creation. Creation, conversely, was aimed at providence; creation conferred on creatures the kind of existence that can be brought to development in and by providence. For the world was not created in a state of pure potency, as chaos or as a nebulous cloud, but as an ordered cosmos, and human beings were placed in it not as helpless toddlers but as an adult man and an adult woman. Development could only proceed from such a ready-made world, and that is how creation presented it to providence. . . . Every creature received a nature of its own, and with that nature san existence, a life, and a law of its own. Just as the moral law was increated in the heart of Adam as the rule for his life, so all creatures carried in their own nature the principles and laws for their own development." (609)
It is at this point he brings up miracles, and although making the point that we should not think of miracles as divine interventions in creation, since God is never not working in creation, wants to avoid pushing this line of argument too far:
"For that reason a miracle is not a violation of natural law nor an intervention in the natural order. From God's side it is an act that does not more immediately and directly have God as its cause than any ordinary event, and in the counsel of God and the plan of the world it occupies as much an equally well-ordered and harmonious place as any natural phenomenon. In miracles God only puts into effect a special force that, like any other force, operates in accordance with its own nature and therefore also has an outcome of its own.
"But at the creation God built his laws into things, fashioning an order by which the things themselves are interconnected. God is not dependent on causes, but things do depend on one another. That interconnectedness is of many kinds. Although in general it can be called 'causal,' the word 'causal' in this sense must by no means be equated with 'mechanical,' as materialism would have us do. A mechanical connection is only one mode in which a number of things in the world relate to each other. Just as creatures received a nature of their own in the creation and differ among themselves, so there is also difference in the laws in conformity with which they function and in the relation in which they stand to each other.
"These laws and relations differ in every sphere. . . . It is the providence of God that, interlocking with creation, maintains and brings to full development all these distinct natures, forces, and ordinances. In providence God respects and develops—and does not nullify the things he called into being in creation. It does not pertain to divine providence to corrupt the nature of things but to preserve [that nature]. . . . Thus, therefore, God preserves and governs all creatures according to their nature, the angels in one way, humans in another, and the latter again in a away that differs from animals and plants. But insofar as God in his providence maintains things in their mutual relatedness and makes creatures subserve each other's existence and life, that providence can be called mediate." (610-11)
So yes, things do have natures, determinate ordered causal relations which God has appointed at creation and continues to uphold at every moment. These natures may unfold in time as seeds do into trees, as God brings them to full development, but in this process, he does not have to remake what he has once made; his providence does not become a form of continuous creation.