1. Introduction
Up until around 1670, the natural philosophy of the Agen-based physician and philosopher Julius Caesar Scaliger (1484–1558)Footnote 1 was a constant point of reference for works in the Aristotelian tradition and for works developing a mechanistic view of nature. On first sight, the presence of aspects of Scaliger's thought in such diverging contexts seems puzzling. Scaliger's commentaries on Theophrastus’ Historia plantarum and De causis plantarum and the Pseudo-Aristotelian De plantis Footnote 2 and his Exotericae exercitationes, a 1,000-page response to Girolamo Cardano's De subtilitate, strike the reader as fragmentary and chaotically organized, deeply imbued in philological reasoning and remarkably disinterested in new observational data. Yet, as seminal studies by Norma Emerton and Christoph Lüthy have brought to light, Scaliger's writings on natural philosophy are interspersed with numerous innovative ideas that proved to be influential in the development of early modern corpuscularian matter theories (see Emerton Reference Emerton1984, 90–102; Lüthy Reference Lüthy2001). In what follows, I will examine one of Scaliger's innovative ideas in natural philosophy – the view that in singular cases the occurrence of new plant species is a genuine possibilityFootnote 3 – and I will discuss a tension that seems to arise between this idea and some of Scaliger's (also quite innovative) ideas in philosophical theology – in particular, his view that the ordained power of God is bound to choose to create the best possible world.Footnote 4
To be sure, Scaliger does not plunge all at once into a modern conception of species, nor does he believe that any species could develop into another species. In fact, he explicitly denies the latter claim (see Scaliger Reference Scaliger1556, fol. 177r-v) and endorses an essentialist conception of species – the view that essences define species membership (see Scaliger Reference Scaliger1556, fol. 339v-340r). Still, his view departs from the doctrine of species fixism – the view that no new species can come into being – that was universally accepted by his contemporaries. Contrary to species fixism, he holds that living beings can come into existence that belong to species that did not exist before. Yet, this claim seems to be in tension with Scaliger's version of the scholastic conception of ordained divine potency. While the tradition going back to Duns Scotus emphasized the central importance of the divine will in constituting the ordained power of God,Footnote 5 Scaliger rejects the view that any law chosen by God could be regarded as an expression of divine goodness; rather, he maintains that only the actual world is the best possible world. Understanding the ordained power of God in this way, however, obviously leads to a pressing problem concerning species mutability: How could the world be the best possible world and yet presently lack some biological species that might develop later? If the world is now as good as it can get, would not new biological species make it less perfect? Or, if they would make the world more perfect than it is now, would this not imply that the world is now less perfect than it might have been? And if the occurrence of new species would imply that the world is less perfect than it might have been, how could their occurrence be understood as an expression of the ordained power of God?
As it turns out, Scaliger's writings on natural philosophy contain scattered but interrelated remarks that will lead to a resolution of this apparent tension. I will proceed in four steps: First, I will establish that Scaliger makes a substantial claim with respect to the possibility of the occurrence of plant species that never existed before. Second, I will spell out the aspects of Scaliger's philosophical theology with which his denial of species fixism seems to be in tension. Third, I will draw an analogy between Scaliger's views concerning species changes involving only previously known species and species changes leading to new species, an analogy that indicates in which sense species change for Scaliger does not involve the occurrence of new essences. And fourth, I will expand the same analogy in order to give a hint at how the development of new species can be understood as an expression of ordained divine potency even if it leads to species that are less perfect than some of the existing species.
2. Scaliger's Claim
It will be useful first to get a clear grip on Scaliger's claim with respect to the possibility of the occurrence of new plant species. Traditionally, the doctrine of species fixism was understood as a straightforward consequence of two assumptions: (1) the assumption that a certain species of living beings is defined by a certain essence common to all individuals belonging to this species, and (2) the assumption that essences are immutable (see Hull Reference Hull1965; Atran Reference Atran1987; Atran Reference Atran1990, 138–142). Species fixism, in Aristotelian natural philosophy, of course was seen as compatible with natural changes that involved the transition of one individual from membership in one species to membership in another species, as in the transformation of elements (for example, from fire to air) or in the transformation of mixtures (for example, from wine to water). It was also seen as being compatible with the assumption of the existence of “spontaneous generation,” for example, the generation of bees from the cadaver of an ox. Such changes involve changes in substantial form (the substantial form of air is not the substantial form of fire, the substantial form of a mixture of a lot of water with a little wine is not the substantial form of a mixture of a lot of wine with a little water, and so on); nevertheless, species fixism holds in such cases because after the change we encounter substantial forms that belong to previously existing species.
Scaliger holds that there are two senses in which one can speak of the possibility of the occurrence of new species. The first sense does not imply an outright denial of species fixism. According to the first sense in which new species can occur, “things that already exist are mixed: such that they will not be inwardly and simply new; for they are made out of those that already exist, as it were, as out of parts: which we see happen in graftings which did not exist before” (EE, fol. 319v).Footnote 6 What is the relevant sense of “mixture” here?Footnote 7 Unfortunately, Scaliger never discusses what is going on in grafting in much detail. However, there is a related case, which he also conceptualizes in terms of “mixture,” namely, the cross-breeding of animals. His account of cross-breeding is firmly placed in the context of his conception of a plurality of substantial forms in each living being. In this respect, he takes up a long tradition from medieval philosophy that is sometimes called “Latin pluralism.” According to the basic insight shared by the members of this tradition, in each living being there is a single dominant substantial form and a large number of subordinate substantial forms that actualize subordinate body parts.Footnote 8 In the following passage, Scaliger explicates in a single breath the nature of the subordination relation and how this relation can be used to account for cases of cross-breeding:
The less noble bodies are made for the sake of the more noble bodies. In the same way, also forms are made for the sake of forms. For example, it is certain that the forms of a horse and an ass mix. Since this is so, all arguments [to the contrary] dissolve. Hence, not only the forms of elements, but also of wine, and of some animals can be mixed in such a way that out of two or more there arises an actual per se unity. (EE, fol. 144v)Footnote 9
This passage indicates that the subordination relation is to be understood as a relation of final causation. Some material objects and some forms are less “noble” than others because they are made for the sake of other material objects and other forms. With respect to the structure of living beings the picture that is suggested by this passage would be the view that bodily organs such as a nose or an eye, as well as their respective forms, are less “noble” than the entire body of the living being and its soul because they are made for the sake of the entire body of the living being and its soul. In this sense, subordinate forms that are all teleologically directed towards the dominant forms can be said to be “mixed” and to form a unity. Such an interpretation is fully consistent with Scaliger's claim that the forms of the most perfect living beings do not “mix” because they are the only ones that are not directed towards any further goal (EE, fol. 145r).
Scaliger does not tell us whether in the case of the generation of a mule a substantial form originating from a horse or a substantial form originating from an ass takes over the role of dominant form. But whatever the dominant form may turn out to be, it seems to proceed from an animal with a dominant form of the same species. And in this sense, a mule should rather be regarded either as a horse or as an ass with a modified teleological structure of subordinate forms rather than as an animal that belongs to a species that did not exist before. Scaliger's account of cross-breeding may also give a hint as to how he wants the relevant kind of “mixture” in the case of grafting to be understood: most plausibly, in grafting the dominant form of one plant becomes subordinate to the dominant form of another plant (even if it might be undecided which form performs which role). If this is what Scaliger has in mind, it also becomes clear why he thinks that the result does not genuinely belong to a species that did not exist before: the dominant form in any case is the dominant form of a plant that existed before grafting took place.
The second sense in which, in Scaliger's view, the possibility of new species can be understood is meant to go beyond the newness that can be achieved by grafting. According to this second sense, new species “are in the potency of an agent . . . For a rose can be produced which did not exist before. But there is always something there, because it is in the potency of the rose bush” (EE, fol. 319v).Footnote 10 Unlike the plants arising from grafting, such a plant belongs to a species that is “simply” and “inwardly” new; but nevertheless such plants are characterized as the result of something that is “already there” in the potency of an existing plant. The example given by Scaliger is certainly bewildering because, from a contemporary perspective, a new variety of rose would not be a plausible candidate for a new species. Nevertheless, even if the example is chosen inconsiderately, what Scaliger has in mind is the question of species membership. This can be gathered from the context in which the rosebush passage occurs – a longer discussion on the question “Whether nature knows animals themselves only with respect to their genus, or also their parts, or also individuals,” considered by Cardano and Scaliger alike (Cardano Reference Cardano1550, fol. 208r-v; EE, fol. 319r).Footnote 11 Cardano gives the following answer:
This is an issue full of doubts: Why are there not more genera of animals, if nature strives to produce everything that it was able to produce; or why has nature contented itself with these genera alone . . . [O]ne or the other horn of this alternative seems necessary to me: either that the forms of individuals are constituted by the number and forms of stars; or that they are perpetually varied through the passage of time, which is indicated by their diversity in different regions . . . and in different times. (Cardano Reference Cardano1550, fol. 208v-209r)Footnote 12
Scaliger's response comes in two parts. The first part complains about the evasive nature of the first horn of Cardano's alternative: “As the number of stars is determinate, nature also has a determinate number, namely, one. Hence, in the same way that we ask whether nature that is one can produce more than it did, we can also ask: Can ten stars, say, produce two species in addition to the ten species that they already produced?” (EE, fol. 319r).Footnote 13 The second part of Scaliger's response takes issue with the second horn of Cardano's alternative: “The other response does not demonstrate a variation of substance but only of accidents. For if a substance that was one became another through place, place would be the giver of forms. Even humans would become different, and probably something other than humans, if placed elsewhere. And the same has to be said to you with respect to time” (ibid.).Footnote 14 Thus, for Scaliger the notion of species membership – for instance, what distinguishes humans from beings of another kind – is closely connected with the notion of substantial form. And Scaliger's point seems to be that a “variation of substance” amounts to the occurrence of a new species.
Such a reading is confirmed by a remarkable passage from his commentary on Theophrastus’ De causis plantarum. There, he mentions that Plinius reports that a (not clearly identified) plant called “silphium” was newly generated through some extraordinary meteorological phenomenon (Scaliger Reference Scaliger1566 [hereafter CA], 16). Scaliger uses the passage from Plinius to conceptualize the possibility of the occurrence of new species in terms of the occurrence of a new substantial form. As he puts it, the question “whether new species, which never before existed, can be generated?” boils down to the question “can a new form arise that shapes matter for its own purposes?” (ibid.).Footnote 15 As he believes, if what is reported is true (and he does not adduce any contrary reasons) “we are forced to confess that a new form can arise” (ibid.).Footnote 16 Thus, Scaliger seems to be committed to the view that, in singular cases, plants can occur that belong to a plant species that did not exist before.
Still, one might wonder why the occurrence of a single individual with a new form should be enough to constitute a new species. Would not the occurrence of several individuals with certain morphological similarities matter as well? The answer seems to lie in the close connection that Scaliger establishes between the notions of form, essence, and species. About a substantial form that shapes matter for its own purpose he writes: “this is essence and what we call species” (CA, 16).Footnote 17 Moreover, he explains that essence is what determines the activities characteristic of individuals belonging to a certain species: “A fly cannot exist unless by means of a fly essence. And the essence determines and constitutes that it nourishes by sucking” (EE, fol. 323v-324r).Footnote 18 Scaliger points out that such a notion of species derives from Themistius’ commentary on De anima (EE, fol. 324r). In fact, Themistius understands the notion of species not as a logical notion derived from some similarity between individuals; rather, in his view “a species loves to be some nature and form. For once human reason is conjoined with matter, a human being arises” (Themistius Reference Barbaro1499, fol. 68v).Footnote 19 The species to which an individual belongs thus is understood as a constitutive principle that this individual can share with other individuals. Such a characterization fits neatly with Scaliger's view of essences. For Scaliger, one could say, essences are principles that determine the goals of those activities without which individuals could not be what they are. And by determining such goals of characteristic activities they define species membership.
This is why, for Scaliger, the number of individuals belonging to a particular species is of no concern. A single rose that instantiates an essence other than the essences of all previously existing plants would make up a species of its own. But this is what one would expect in the framework of an essentialist conception of species. In fact, in Aristotelian and Arabic cosmologies, heavenly spheres and heavenly bodies for a long time were regarded as instances of such one-individual species.Footnote 20 What is new about Scaliger's view is that he applies the concept of a one-individual species to a different realm – the realm of plants – and that he claims that a one-individual species that did not exist before can come into being. Of course, Scaliger never claims that new plant species necessarily comprise only one member. On the contrary, he easily could accommodate the view that the process in which an individual rose belonging to a new species occurs can be repeated in other instances, thereby leading to a species comprising several individuals. In fact, in the passage referred to by Scaliger Plinius’ clearly states that silphium occurred in quantities sufficient to develop a medical use of the plant. Still, with respect to Plinius’ report Scaliger frames his claim in terms of the occurrence of a new substantial form (in the singular). In Scaliger's view, it is essence, not the number of individuals that matters for the individuation of a species.
Scaliger's claim thus seems to be that, in some cases, plants can arise that belong to no previously existing plant species because their substantial form instantiates an essence that was not instantiated by the substantial form of any previously existing plant. To be sure, there are only two passages in which Scaliger makes this claim, and in neither passage does he elaborate on the claim. Nevertheless, it is a claim that deserves attention for two reasons. First, within an essentialist conception of species it denies an assumption widely held to be a consequence of essentialism about species, namely the assumption that the number of existing species cannot become greater. And in this respect Scaliger seems indeed to have been exceptional among his contemporaries. Second, the idea that there is something “in the potency” of a rose bush stands in close thematic connection with Scaliger's scattered but interrelated remarks on the nature of dominant and subordinate forms in living beings. Taking this background into consideration, as I will do in section 4, will make it clear that Scaliger's remarks about the possibility of the occurrence of new plant species are much less ad-hoc than might be evident on first sight.
3. A Problem with Ordained Divine Power
Even if Scaliger's claim concerning the occurrence of new species, for reasons just mentioned, deserves attention, it seems at the same time to be incompatible with Scaliger's own philosophical theology. This is the central problem that the present article addresses. To see the problem more clearly, it will be useful to scrutinize Scaliger's remarks on divine potency in some detail. Scaliger accepts the scholastic distinction between absolute divine potency and ordained divine potency. With respect to the former, he holds that extraordinary divine interventions are possible: “A single being is the first, hence all other beings depend [on it] . . . But every dependent being can be changed by the being on which it depends, if this is a voluntary principle” (EE, fol. 405r).Footnote 21 Existential dependence of natural beings on a first being endowed with will thus implies the possibility of being changed at any time by the will of the first being. Yet, Scaliger does not resort to the absolute power of God in explaining the possibility of new biological species. Rather, he regards changes in species membership as an expression of the order of nature and, hence, of the ordained power of God (see Scaliger Reference Scaliger1556, fol. 177r-v). For Scaliger, what unites the two kinds of divine power is that divine power involves both an aspect of immutability and an aspect of change:
We cannot define providence, but perhaps we may explain it thus: It is the power of God that is always present to itself and prior to everything else. Therefore it is simple and one; and for this reason it is immutable. For if it is prior to everything else, it is not changed by it, but changes it. If it is present to itself and simple, it is not changed by itself from within. (EE, fol. 410r)Footnote 22
Thus, the immutability of divine power is due to the simplicity of the divine essence. At the same time, the immutability of divine power is described as being compatible with changes in the world. What is more, a certain aspect of divine power accounts for changes that take place according to the order of nature: “Nature is the power of God with respect to all orderly motions” (ibid.).Footnote 23 This can be understood as Scaliger's explication of the notion of ordained divine power. But what, in his view, does this power consist in? There are some passages that might lead Scaliger's readers into believing that he defends some version of pantheism. One of them runs as follows: “That nature is nothing but God himself . . . is evident from the fact that all things that do something act by dint of the power of the first agent” (EE, fol. 120v-121r).Footnote 24 And shortly afterwards, Scaliger writes:
That God and nature are the same is evident from De caelo I, 32, where Aristotle says that ‘God and nature do nothing in vain’ . . . In fact, he appointed nature here not as assisting cause, but in order to explain within the infinite potency, which is known under the name of God, the potency that he claimed to be ordained and that we call nature. (EE, fol. 121r)Footnote 25
Here, Scaliger invokes the Scholastic notion of the ordained power of God that was traditionally distinguished from the notion of the absolute power of God. Later, he mentions that Duns Scotus explains the distinction between “absolute” and “ordained” power in juridical terms: A person acts “ordinarily” who acts according to a law. But two cases can be distinguished. Either the person is not able to change the law. In this case, there would be no other way for her to act rightly – every act that contradicts the law would be inordinate. Or the person is able to change the law. The ability of changing the law is “absolute” potency. Scaliger notes that when we follow the lead of Scotus and apply this conception to God, we come to the conclusion that, due to his “absolute” potency, God could change the law such that he, after the change is completed, is able to act rightly according to the new law, again in an “ordained” way (EE, fol. 320r-v).Footnote 26
At this juncture Scaliger departs from Scotus. He notes that, according to Scotus, another “law also would be the right law, if it were decreed by God.” And he concedes that “it is evident: if God makes another law, this law will be the right law in the future.” However, he objects:
[I]n every action there is only one right action: and this is constituted by The Right, that is, what is right in the highest degree, that is, by God himself. Therefore, whatever is right besides this does not belong to God, but to something that is not God. Because to do something less good implies a privation of supreme goodness and supreme power . . . Hence, he could act differently, because in the highest potency a minor potency is comprised, as well. Thus, he could do so out of the immensity of potency. But out of the highest goodness, which is the rule for potency . . . he does not want to be capable of less than to be capable of acting well. (EE, fol. 320v)Footnote 27
Thus, Scaliger's conception of the “ordained” power of God is closely connected with his view that God acts in the best possible way. God could have chosen, by means of his “absolute” power, a different world. Nevertheless, the world that he actually has chosen is the best possible world (ibid.).Footnote 28
This is a substantial difference between Scotus’ and Scaliger's views on the goodness of the laws underlying the natural world: For Scotus any consistent combination of laws chosen by God would, by this very fact, be good and an expression of the divinely chosen order; for Scaliger only one single combination of laws can be the best possible one and, for this reason, is chosen by God. In this sense, there is only a single combination of laws that can be regarded as the expression of the ordained power of God. Any other possible combination of laws would be inordinate because they would realize a world that is less good than the actual world. For Scotus, God could act ordinately in all logically possible ways; for Scaliger, God could act ordinately only in a single possible way that corresponds to divine goodness.
This difference is connected with a no less substantial difference in the importance that Scotus and Scaliger assign to the divine intellect. For Scotus, what matters is that the divine will chooses one consistent combination of laws; the divine intellect is involved in this process, but for Scotus the intellect's role reduces to providing the will with information concerning the coherently thinkable combinations of laws. In this sense, it is not the divine intellect that is a source of the goodness of the chosen combination of laws; rather, the chosen combination of laws is good because it is chosen by the divine will. And because the divine will is free to choose any logically coherent combination of laws, any logically coherent combination of laws chosen by the divine will would be the expression of divine goodness. By contrast, Scaliger describes the role of the divine intellect as follows: “God generates . . . out of himself, in himself, the understanding of himself, in the same way always the same and equal to himself, because he does not understand by means of species but through the presence to himself” (EE, fol. 473r).Footnote 29 For Scaliger, what comes first is the insight of the divine intellect into the divine nature, an insight which includes an insight into the divine goodness and omnipotence. This gives an answer to why, for Scaliger, the divine will chooses the combination of laws that the divine intellect regards as the best: the divine intellect determines the divine will to create the best of all possible combinations of laws because the divine intellect possesses reflective knowledge about divine goodness and omnipotence. In this sense, Scaliger's view of how the divine intellect is constitutive for the ordained power of God is very different from Scotus’.
Interpreting the ordained power of God in the way Scaliger does makes the question of how new biological species can come into being even more pressing than from the perspective of Scotus’ interpretation. For Scotus, the actual world is the best in the sense that adding or subtracting beings in it would make it less good. In this sense, every possible world is a sort of optimum that would become less good by adding or subtracting beings. Scotus’ position seems to imply that there could be other biological species than those that actually exist; but they would have to be part of other possible worlds. For Scotus, relative to laws that flow from other possible acts of the ordained power of God, they could be part of other natural orders; but given that laws that flow from the actual act of the ordained power of God, their occurrence would be inordinate – their occurrence would be possible but it would make the world less good. By contrast, if there is only one possible course of action that the ordained power of God could have taken, thinking of other biological species as part of other natural orders does not help. This is why for Scaliger other possible worlds cannot be understood as alternative outcomes of the ordained power of God. And in fact, Scaliger does not invoke alternative natural orders when he speaks about the possibility of the occurrence of new species of living beings. Rather, he regards this possibility as being inherent in the actual world.
On first sight, such a view seems to face insurmountable obstacles within Scaliger's own conception of divine agency. Consider the following implication of the notion of perfection: “Perfect is that to which nothing can be added. Hence, an entity to which nothing can be added will exist perpetually. Likewise, an entity in which nothing belonging to essence can be changed” (EE, fol. 319v).Footnote 30 Hence, the perfection of the world implies that nothing pertaining to the essence of the world could be changed without making the world thereby less perfect. Creating anything in addition to what the world already contains therefore would be incompatible with the perfection of the world: “Can God create and add there something new? He can. But he does not want to be able to: because he would accuse himself of a less perfect work than what he had put in his previous work” (EE, fol. 320v).Footnote 31 Consequently, it seems that Scaliger would have to regard the occurrence of new species of living beings as a possibility that would go beyond the ordained power of God.
4. Species Change as Relational Change
Does Scaliger's philosophy contain the resources to resolve the tension between his denial of species fixism and his conception of the ordained divine power? I believe that it does. To see this, we will first need to get some grip on his views on changes in species membership involving only previously existing species. Such cases obviously do not pose any problems for Scaliger's theological views; nevertheless, they provide helpful background for understanding his solution for those cases that seem to be in tension with his views on the ordained power of God. Scaliger's scattered remarks give some coherent hints at how his ontology of a plurality of substantial forms in living beings allows for such changes in species membership involving only previously existing species. Moreover, these remarks suggest that the processes underlying the occurrence of new species of living beings are closely analogous to the processes underlying the changes in species membership involving only previously existing species.
Scaliger mentions two examples of transformations between previously existing species that were widely discussed in ancient biological works: the change of darnel into wheat, and the change of water-mint into mint. Of course, from a contemporary perspective, we would interpret such cases as changes from a wild variety to a cultivar. Nevertheless, what Scaliger has in mind in discussing these cases, whether empirically adequate or not, is the issue of a change in species membership. This becomes clear when, with a view to these cases, he is careful to note that change can take place either with respect to substance, or quantity, or quality (CA, 288). He maintains that while changes with respect to quantity and quality do not constitute differences in species, a change in substance does (ibid.). And such a change of the whole species (mutatio totius speciei), in his view, takes place when water-mint changes into mint (ibid.). He describes this change as follows: “When mint changes into water-mint, or vice versa, this happens due to the affinity of forms; and if the species differs also matter differs” (EE, fol. 386v).Footnote 32 Clearly, changes in species membership here are connected to changes of the level of substantial forms. However, what does Scaliger have in mind when he speaks of the “affinity of form”? Commenting on Theophrastus, he analyzes the analogous case of darnel and wheat as follows:
At the same time, he shows the mode in which darnel arises and explains the reason by means of which this can take place. The mode is the following: if the seed is inwardly corrupted, the form of the plant is not abolished but becomes another form. He proves that this can take place when he says that the nature of plants is full of life, and indeed fuller of life than the nature of animals and therefore productive. (CA, 230)Footnote 33
Darnel is a case in which a plant of one species has its origin in the corrupted seed of a plant of a different species. The corrupted seed no longer carries the form of the plant from which it originated. But it is also not altogether different from the form of the plant from which it originated. As I have argued elsewhere, it seems most plausible to understand this passage and those about mint and water-mint in the context of Scaliger's conception of a plurality of substantial forms in living beings. If this is what Scaliger has in mind, what underlies his account of species mutability is the view that domination relations between substantial forms can break down such that a previously subordinate form becomes the substantial form of a new living being.Footnote 34
Scaliger gives an analogous reading to Theophrastus’ account of cases of “spontaneous generation”:
[O]ut of a human being there does not arise a slime, out of which again a human being could arise. From a calf, bees are created, but the nature of bees never returns back into a calf . . . Rather, out of those things that were in the first instance created together, other things follow on those things that decay at the same place. For it is manifest that some kinds of wood . . . have natural rudiments of another species within themselves. If this nature persists and remains intact, it does not so much re-integrate while being in the slime of decayed things; rather, a new generation out of old principles takes place. (Scaliger Reference Scaliger1556, fol. 178r)Footnote 35
Since the “natural rudiments of species” and “old principles” contained in a living being develop into the substantial forms of livings beings belonging to another species, they can most plausibly be understood as subordinate forms dominated by the substantial form of the plant.
Scaliger's claim that in a rose bush “there is always something there” that accounts for the generation of a plant belonging to a new species (EE, fol. 319v) can well be understood against the background of these remarks. Most plausibly, as in other cases of changes of species membership, what is “always there” in the rose bush are some “old principles” or subordinate forms that subsequently become dominant. If this is what Scaliger has in mind, then what is analogous between cases of changes in species membership involving only previously existing species and the occurrence of a new plant species is that in both cases changes in relations of domination and subordination between substantial forms in living beings take place. Can such a process lead to plants that belong to previously non-existing species? Consider that, according to Scaliger, all substantial forms have been created at once in the act of creation.Footnote 36 This seems to imply that, since then, some forms – for example, the forms of parts of organic bodies – have always functioned as subordinate forms. These forms functioned as life-principles of parts of living beings (or other composite substances), but never as life-principles of living beings themselves. Accordingly, the essences instantiated by them functioned as essences of parts of living beings (or other composite substances), but not as essences of living beings themselves. Likewise, these essences defined species of parts of living beings (or other composite substances), but not species of living beings themselves. During all this time, there was no living being that belonged to the species individuated by such an essence. However, assume that once the domination relation between the dominant substantial form and such a subordinate substantial form breaks down, and that during this process a subordinate form becomes the active principle of a living being. In such a case, we are in the presence of a living being whose essence is determined by a subordinate form turned dominant. This essence never before functioned as the essence of any other living being or, equivalently, there never before was a living being that shared the same essence. In such a case, while the substantial form dominating in this living being is old – indeed, as old as the universe – the living being belongs to a species that is new.
In this way, the possibility of the occurrence of new species does not violate the condition that, in the best possible world, no new essences can come into being. This, I believe, is an important part of a solution of the problem of how the view that new species can occur is compatible with Scaliger's conception of the ordained divine potency. Still, it is an incomplete solution. Recall that Scaliger believes that substantial forms that are capable of occurring as subordinate forms are less perfect than dominant substantial forms. So, why should not the death of a more perfect living being and the emergence of a living being dominated by a previously subordinate and, hence, less perfect, form be understood as diminishing the perfection of the universe? In fact, there is an analogous problem for the degeneration of mint into water-mint or of wheat into darnel. And this is why the analogy between species change involving only previously existing species and species change involving also previously non-existing species is helpful also in this case.
5. Species Change and Ordained Divine Power
Let me begin by considering whether Scaliger's claim that nature is the ordained power of God implies that God is an active power immanent in things. This is one of the relevant passages:
[I]f a human being deliberates about actions, it has also this from nature . . .: By its own nature, it is capable of deciding about two contradictory options such that it chooses one of them. From this, we also understand that divine providence is immanent in all things, but not in the same way. For it permits some; others it makes inclined by itself, that is, by means of an influence; others by means of immaterial agents; others by means of material agents, from which the disciplines arise out of the teaching of sciences; others by means of principles that are innate with us. (EE, fol. 410v-411r)Footnote 37
Scaliger indeed seems to be committed to the claim that, in some sense, divine providence is immanent. But it is not evident with respect to all cases mentioned why he believes that divine providence is immanent. It seems rather enigmatic why he believes that divine providence is immanent in the cases in which God does not interfere with the course of events. Other cases involve immanent divine providence in a quite obvious way, namely cases of direct divine intervention and intervention by means of intermediary beings. These cases would fall most plausibly under the heading of “special providence” – something that does not happen according to the ordained course of things. But how should one understand Scaliger with respect to the most interesting class of cases: the agency of natural (material or immaterial) agents?
The relation between God and natural beings is one of the points in which Scaliger markedly departs from Scotus. He attributes to Scotus the following line of reasoning: “Things have essence and existence. Therefore, in creation the things that had essence in the divine mind, that is, in the ideas, undergo change through the addition of existence” (EE, fol. 17r).Footnote 38 Scaliger comments:
This is false. For God would create nothing but an accident, namely, existence itself, which is an accident of essence. That is, he would add nothing to essence that would make something other than essence or more than essence. But this is contrary to the definition of creation. For this was the constitution of substance out of nothing. If existence were a substance that differs from essence, there already were two substances. If it is an accident, God would create an accident. If it is the same as essence, God would create nothing . . . Therefore one has to say: God did not add existence to an essence that was in his mind . . . Rather, he produced new forms that are similar to these essences, and that are not simply univocal but analogous: the ones are only in his will, while he made the other such that they exist in a new contingent manner. (Ibid.)Footnote 39
For Scaliger, the process of creation is not a process in which existence is added to essences that are previously present in the divine mind in such a way that the essences of created things would be identical with the essences in the divine mind. Rather, things have their own essences by means of which they differ from mere accidents. In this sense, natural beings are substances in their own right, and divine immanence cannot be understood as an immanence of divine essence in created beings.
If created beings are substances in their own right, their activities cannot be interpreted as an activity of divine essence. In which way, then, can the activity of created substances be understood as an expression of divine providence? And how could the occurrence of an individual belonging to a less perfect species than the individual from which it originated be understood as being compatible with, and even an expression of, the divine will to create the best possible world? Scaliger connects his views concerning relations between biological species closely with his views on the relation between God and created world:
The first principle was not able to produce something that is entirely similar nor entirely dissimilar to itself. For it was unable to produce something similar because, what comes into being, suffers, and what suffers, suffers from something more potent. And it was unable to produce something dissimilar, because action and agent do not differ in it. Hence, the act, or the product, was necessarily similar in some way and dissimilar in some other way. Therefore, because the principle is one, the world was one and not one . . . Because it is one it is eternal; for it does not have any counterpart or contrary. Because it is not one, it is not eternal; for it is constituted by contrary parts that act on each other destroying each other. Hence, its eternity consists in succession, its unity in continuation. (I now understand eternity as perpetuation, to which the principle imposes an end when it seems fitting to it.) Therefore the world must have two ideas of forms. One is particular, relating to each of the species contained in it, relating to the generation, motion and extension in those entities by means of which it is not one. The other is universal and serves the purpose of conserving unity. (EE, fol. 6r)Footnote 40
In this passage, Scaliger combines a sense in which the world is one with a sense in which the world is not one. The world is not one because it is composed of parts whose causal relations are opposed to the conservation of the parts. In this sense, there is a perpetual change in the parts constituting the world. At the same time, the world as a whole does not stand in causal relations that could be opposed to its conservation to anything external to it. In this sense, the perpetual change in the parts constituting the world is not contrary to the view that the world as a whole does not undergo destruction. Scaliger is also explicit about the distinction between ideas and forms. It seems plausible to understand ideas as essences in the divine mind, while forms that exist in the natural world are the factors that account for the substantiality of created beings. Interestingly, Scaliger claims that ideas relate in a dual way to forms: In one way, ideas relate to forms under the perspective of how species are constituted by natural particulars that undergo processes such as generation and motion. In this way, ideas relate to forms under the perspective of what makes the world a being that is not one. In another way, however, ideas relate to how forms account for the conservation of the unity of the world.
What does Scaliger have in mind? One of his responses to Cardano may give a clue. Cardano argues that species of living beings are not made for the sake of other species, because many individuals belonging to species “live and die for their own sake” (sibi vivant & moriantur) (Cardano Reference Cardano1550, fol. 209r). This is Scaliger's reply:
When you say that not all flies are eaten by the swallow, [this is so because] these individuals miss by chance the end of their species . . . [This is the] proof: That without which something cannot exist in nature is necessary for it or made for the sake of it. Without the fly the swallow cannot live. (EE, fol. 323r)Footnote 41
Here, Scaliger gives clear voice to the idea of a teleological relation between biological species. This teleological relation does not necessarily hold on the level of individuals – of course, not all flies are eaten by the individuals belonging to species that feed on flies – but the teleological relation on the level of species shows itself in the existential dependence of one species on another – the case in which one species could not survive without feeding on members of another species. As it turns out, such relations of existential dependence are, in Scaliger's view, often reciprocal:
[T]hose who think that species are made by God for the sake of variety, not for the sake of a certain end, propose no other end in nature than being idle . . . In order for this fly and this butterfly to be able to dance on holidays, it is burdened with serious duties towards the more noble species . . . For variety is not the goal that nature pursues. Rather, it is a means for the perfection of the universe. For nature itself is in a manifold way one; [a unity] which consists in how the forms are constituted, in their mutual necessity and order. (EE, fol. 323r-v)Footnote 42
Here, Scaliger characterizes the relation between different species in terms of a relation between different substantial forms. In fact, the mutual dependence between substantial forms for him is only one case of a whole group of relations of existential dependence in nature:
Because the creator wants to preserve the world, he joined to the parts of each genus a propensity and efficient power to fulfil mutual duties. In this way, wheat serves as the matter for a mouse, the force of the sun as the form. In this way, form gives to matter that it is this particular something; matter gives to form that it is exists here and now . . . Form gives to the accidents that they exist; the accidents give to form that it acts in this way . . . In this way the forms of species are mostly conserved through their utilities and the utilities through the forms. Such that even the human species is assisted by most of the other species; and the human species assists many of them. (EE, fol. 324r)Footnote 43
For Scaliger, relations of mutual existential dependence between biological species are an instance of a whole group of relations of existential dependence that lie at the heart of his conception of the unity of the world. And such relations of mutual existential dependence between biological species belong to those relations that the creator brought into being in order to preserve the existence of the world. In this way, fulfilling functions towards individuals of other biological species belongs to the activities of substantial forms determined by the ordained power of God: only if substantial forms fulfil such functions can they be said to be part of a natural world ordered in the most perfect way.
Scaliger explicitly connects the issue of species change with the issue of a lawful order of nature when he claims that species change takes place “by means of a decree of nature that strives towards a certain end through certain laws” (Scaliger Reference Scaliger1584, 110–111). The concept of law at stake here is not one that has to do with observable empirical regularities. Rather, it is the concept of law understood as an expression of the ordained power of God:
[N]ature is for all things by itself a principle by means of which they are what they are . . . If all plants are determined by nature, they are also determined by necessity in what they are. Some of them, I say, perpetually, like those that do not undergo change. Some of them not perpetually, like those that undergo change, either by means of the seed that brings forth wheat or after sowing, as we said about mint. Nevertheless, the principle that consists in being mutable is itself immutable. For this reason, nature is the ordained power of God. (Scaliger Reference Scaliger1556, fol. 177r-v)Footnote 44
Both seeds and young plants are determined to develop in a particular way, but their way of being determined is compatible with the view that both seeds and young plants can develop into plants of a species other than the plant from which they originated. For Scaliger, the transition of an individual from one known species to another known species is laid down in the natural powers of things themselves, which are understood as secondary causes created according to the decrees of divine providence. In this way, whether the transition leads from a less perfect being to a more perfect being or from a more perfect being to a less perfect being is irrelevant for the question whether such changes in species can be understood as expressions of the ordained power of God. Even if they, in a particular case, lead to the existence of a less perfect being, what matters from the perspective of divine decrees is the resulting perfection of the universe. And, as we have seen, the perfection of the universe is measured not by the relations of mutual existential dependence between species. God wants what is best for the preservation of the universe as a whole, and if, due to the mutual dependence between species, the occurrence of some individuals belonging to a less perfect species is called for, this is exactly what the laws underlying the best possible world demand. An analogous consideration can be applied to individuals that belong to new species: These new species are not necessarily more perfect than previously existing species. But again, the degree of perfection of a particular species is not what matters. Rather, if the divine will to create the best possible world boils down to permitting those species to develop that are most useful for the preservation of other species, the occurrence of new species is compatible with the ordained divine potency as long as they contribute to the preservation of other species in the best possible way.
6. Conclusion
Thus, the tension between Scaliger's claim that the occurrence of new species of plants is a genuine possibility and his view that God creates the best possible world is only apparent. It can be resolved by paying attention to two elements in Scaliger's thought: The first is his view that what matters for species change is a change in the relation of subordination and domination between substantial forms. As we have seen, he applies such an analysis to cases of species change involving previously known species, and it can consistently be extended to an analysis of cases of species change leading to new species. New species do not require new essences and are therefore compatible with the requirement that to the best possible world no essences can be added. The second element relevant for dissolving the apparent tension is Scaliger's view that what matters for the perfection of the universe is not the sum of the degrees of perfection of single species but rather the capacity of single species to contribute to the preservation of other species. Species changes leading to less perfect species do not diminish the perfection of the universe as long as the occurrence of less perfect species is best for the preservation of other species. Again, this thought can consistently be extended to the occurrence of new species: as long as they contribute to the perfection of the universe as a whole, their occurrence can be understood as being compatible with, and an expression of, the ordained power of God.
