Bacon (c. 1220–1292) and his System of Laws of : Classification, Hierarchy and Significance

Yael Kedar Tel Hai College

Giora Hon University of Haifa

Bacon discussed three different types of laws of nature: (1) particular laws governing one element or (such as the of the gravity of water); (2) the laws of the of species; and, (3) the universal law of nature. Each set of laws has its own explanatory : (1) the particular laws account for the unique features of individuals and species; (2) the laws of multiplication explain the common features of matter and how individuals affect one another physically; and (3) the law of universal nature regulates these interactions and keep them in balance. Bacon’s laws share common fea- tures with early modern conception of laws. For example, they can be restated as if/then sentences and cover events; some support counterfactuals; and all are endowed with and free from -time limitations. When considered together, they form a system, ordered in hierarchical relations. The different levels of laws cover three aspects of Aristotelian : formal, efficient, and final. The law of universal nature is a metaphysical , necessary for upholding the very idea of a nature governed by laws. This indicates that Bacon conceived of nature as orderly and predictable; he presented a conception of a lawful nature and showed an understanding of what it takes to be lawful to a degree that had not been seen before.

1. Introduction The idea that nature is governed by laws and that the goal of is to discover and formulate these laws, rose to prominence during the Scientific

This research was supported by the Israel Science Foundation (grant no. 1622/13): “ (c.1220–1292) and the Making of the Concept of Law of Nature.”

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Revolution of the seventeenth century. It was manifestly held by the most significant actors of that revolution such as Galileo, Descartes, Kepler, Boyle, and Newton. But this idea was not new. In , it made an appear- ance in the , and it is likely to have emerged already in Antiquity (Ruby 1986; Lehoux 2012; Kedar and Hon 2017).1 In this paper we pay close attention to the concept of law of nature in the writings of Roger Bacon, the outspoken Franciscan who promoted ex- perimental science. We will be using Bacon as a test case to show that long before the scholars were working toward the idea of law of nature. Some historians of science hold that even if the concept of law of nature can be found prior to Descartes, its content was significantly different from the seventeenth-century concept (for example, Henry (2004, 2009)). We do not question this claim. Rather, our goal is to find, de- scribe, and characterize any usage which Bacon made of the term lex in connection with natural processes in the physical world. Typically, the term lex would refer to a description of regularities in nature, play an explanatory role, and be linked to mathematical concepts.2 Upon reading Bacon’s corpus, one cannot but notice the pronounced and broad use of the term lex in several contexts. We examine the various kinds of laws which Bacon introduced, describe their applications in the contexts they are found, and interpret their meanings. We classify the laws, identify the relations among them and the hierarchy they form. Fi- nally, we ask, what did Bacon mean when he appealed to this concept and whether this meaning is like the early modern one? To be sure, Bacon’s appeal to the concept of law of nature was noted in several earlier studies, such as Crombie’s (1959, 1996), Schramm’s (1981) and Ruby’s(1986). However, none of these studies offer a comprehensive description, nor an analysis of the specific laws which Bacon prescribed. Crombie provided a few quotations referring to Bacon’s optical laws and claimed that they demonstrate a shift in , but he did not investigate them any further; Schramm commented only on the law of universal nature; and Ruby ad- dressed the origins of the concept of law of nature in Bacon’s optical works and analyzed the relations between the terms regula and lex in his thought. She referred to Schramm’s treatment of the law of universal nature, but

1. Ruby argues that the modern concept of law of nature appeared in three different processes at different times in different fields all prior to the time of Copernicus. Lehoux maintains that a concept of law of nature, similar to the early modern one, can be found in premodern sources such as . Kedar and Hon claim that and Roger Bacon facilitated a coherent conception of both “” and “laws.” 2. Expressions including the phrase “,” which in most cases appear in moral and political contexts, do not fall under this category.

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dismissed this law as resulting from a different motivation and as irrelevant to Bacon’s set of optical laws. Lindberg (1968), Smith (2015), and a few other scholars discussed Bacon’s treatment of the optical phenomena of reflection and , but have not paid attention to his use of the term lex in these contexts. Above all, Bacon’s laws of particular natures have not yet been investigated, nor is there a study of the linkage between the various kinds of laws which sets them into a hierarchical system of signif- icance. With this paper we seek to address this lacuna. We begin with a classification of the various laws of nature invoked in Bacon’s writings and we set them in their order of generality. We suggest three categories, namely, (1) laws of particular natures, (2) laws of the multiplication of species, and (3) the law of universal nature. In the section we examine the relations between the various laws and determine whether they constitute a coherent system. In the third section we address the meaning of the phrase “laws of nature” in the way Bacon used it, and suggest insights as to its historical significance. This last section builds on the comprehensive study by Weinert (1995) in which he maps various types of laws of nature and provides criteria for distinguishing laws of nature from accidental regularities. Weinert sums up effectively most of the literature on this subject prior to 1995 which makes his mapping most helpful. Bacon developed the concept of law of nature in De multiplicatione spe- cierum and De speculis comburentibus from the late or the early , the and Opus tertium from 1267–1268, and the Communia nat- uralium and Communia mathematica from the late 1260s and early 1270s (Easton 1952). These texts are assumed to comprise the most mature expressions of many of Bacon’s . All of them belong to the period after Bacon’s supposedly crucial encounter with the writings of Robert Grosseteste (c. 1168–1253) and various sources. Despite Ruby’s claim (1986) that Bacon appeared to have discarded the universal law in the Opus majus and considered it foolish, we show that Bacon addressed the law of universal nature several times in the Communia naturalium and used it to explain not only the impossibility of , but other phenomena as well. It is therefore an inseparable part of the scheme of laws which he constructed. In sum, the thrust of our paper is that Bacon did not intro- duce the concept of lex in isolation; rather, it was part of a hierarchical lawful scheme with a novel explanatory power projecting a new image of nature—a nomological image.

2. Laws of Nature: A Classification We list the three types of laws which we have found in Bacon’s writings. We set the three types in an order of generality, that is, from the particular to the general. We begin with particular laws governing only one element

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or phenomenon (§ 2.1); we then move on to laws governing a larger set of natural elements (§ 2.2); and, finally, we address the one law that encom- passes nature as a whole, namely, the universal law of nature (§ 2.3).

2.1. Laws of Particular Natures The laws of particular natures apply to either one element, one species, or an individual. It is defined as “a reigning power of the species with its individuals … that is, the power reigning the species and the power reigning the individual” (Bacon CN 1.2.3, p. 93).3 (1) The law of the gravity of water According to “the law of the gravity of water” (legem gravitatis aquae), water always runs to the lower place so that their surface is always equally distant from the center of the (Bacon OM 4.4.11, p. 158). The lower the position of the water is, the more they will contract (Bacon OM 4.4.11, p. 159). The water’s surface must form a sphere around the center of the world: If lines be drawn everywhere to the surface of the water from the centre of the earth … and if one of those lines will be shorter than the others, the water will run to the end of that line until equality is established. Therefore all lines drawn in every direction from the centre of the world to the surface of the water are necessarily equal…. Therefore the surface of the water containing the earth ought to be concave, and not of any other kind of concavity than that of the sphere, since in that figure alone, all the diameters are equal. (Bacon OM 4.4.10, p. 156)4 Bacon explained here the tendency of water to run to lower places and the phenomena of communicating vessels in geometrical terms. In the geo- centric model of the universe, which Bacon held, the sphere of water sur- rounds the earth; therefore the surface of the body of water must form a sphere. But this is not all; in a way reminiscent of the much later Stevin’s law, the law of the gravity of water is applicable to the compression of water as well. Bacon demonstrated this part with the of the

3. “Natura particularis est virtus regitiva speciei cum suis individuis et ideo hec est duplex, scilicet, virtus regitiva speciei et virtus regitiva individui.” 4. “Ducantur lineae undique ad superficiem aquae a centro terrae … si una illarum esset brevior altera, aqua curreret ad extrimitatem illius donec aequaretur. Ergo omnes lineas ductas undique a centro mundi ad superficiem aquae aequari necesse est…. Ergo oportet, quod superficies aquae continens terram sit concave, et non cujuscunque concavitatis, sed sphaericae, quoniam in sola illa figura omnes diametric sunt aequales.”

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two cups. Let one cup be placed at a higher place, such as a balcony, and another cup in a lower place, such as a cellar, both cups completely filled with water. Now, according to the law of gravity “[water will] form itself into a smaller and larger sphere with respect to the center of the earth” (Bacon OM 4.4.11, p. 159).5 The water’s surface of the higher cup will be a portion of a sphere more distant from the center of the earth and therefore larger than the surface of the water in the lower cup. The di- ameter associated with each cup will then cut an equal chord (assuming the cups are equal) of each sphere; however, the proportions between the chords and the spheres will be different: the chord of the higher cup will form a smaller part relative to the larger sphere, while the chord of the lower cup will be relatively larger. As a consequence, the water’ssurface of the two cups will differ: the smaller sphere of the lower cup will result in higher surface, while the higher cup’s surface will be lower. Given this situation, Bacon inferred, the lower cup can contain more water than the higher one, since the same amount of water will require less space or, in other words, the water in the lower cup will contract: “more water can be poured into a cup in a low place than the same cup in a higher place” (Bacon OM 4.4.11. p. 158).6 Now, why does water act in this manner? Bacon did not provide us with the standard Aristotelian response that this is the water’s “nature”; rather, he attributed the water’sbehaviour to the “power of geometry” (geometriae potestatem), that is, to the geomet- rical proportions between the cups’ diameters, their distance from the center of earth and the geometrical properties of the sphere (Bacon OM 4.4.11. p. 159). (2) The laws of the stars The astrological “law” governing the influence of the planets over terres- trial elements at the time of ascension was part of the astrological developed by Muslim thinkers such as Abu-Mashar (787–886), whom Bacon had read and cited. In the fourth part of Bacon’s Opus majus,there is an extensive section which discusses the science of ; in this text one finds many phrases such as the “law of ” (legem Mercurialem, Bacon OM 4.4.16, pp. 257 and 261), “law of Venus” (lege venerea,Bacon OM 4.4.16, p. 262), or the “law of the Moon” (lex lunae,BaconOM 4.4.16, pp. 257, 261 and 262). It appears as though Bacon ascribed each planet aunique“law” of its own. This is not, however, the law of the planet’s

5. “Aquae secundum legem suae gravitatis figurantis se secundum sphaeram minorem et majorem respectu centri mundi.” 6. “Potest plus infundi de aqua in scyphum, quando est inferius, quam quando est superius.”

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. The “law of the Moon”, for example, means “ and deceit” (nigromantiam et mendacium,BaconOM 4.4.16, p. 262); and the “law of Mercury” refers to “the depth of knowledge contained in profound books” ( profunditatis scientiae in libris profundis, Bacon OM 4.4.16, p. 257), as well as oratory and interpretation. The virgin birth of Jesus is “in full accord with the law of Mercury, because Mercury was created in the sign Virgo and enjoys the virtues or fortitudes associated with this sign” (Bacon OM 4.4.16, p. 257). These astrological laws are linked with the moral and religious laws of various faiths and nations, such as the “law of the Saracens” or of the Chaldeans (Bacon OM 4.4.16, p. 256), and their meaning is clearly not in accord with the laws which describe regularities in nature. The so-called laws of the stars denote, rather, the mystical and eschatological aspects of the unfolding of history. Moreover, these “laws” are not universal and change over time. The rise and fall of and empires are explained by the revolutions of the planets and their locations in one astrological sign or another. Each planet rules a different region or empire. The “law of the Moon,” for example, will be the last law; it overrides all laws, and even- tually will corrupt itself. This is “the law of the ” (lex Antichristi), because it will appear at the end of the world, and will bring in “the law of corruption” (legem corruptionis, Bacon OM 4.4.16, p. 262). The planets are signs, providing hints as to what God arranged from either through nature or through will and, yet, at the same time influence the elements by way of excitation. To be sure, the account of excitation of the elements may be related to regulations and the order of nature, but evidently the use of “law” in the astrological context is only partially re- lated to natural processes since the law of the Antichrist does not concern the physical makeup of nature. Still, however partial, what we witness is a law of a particular nature.

2.2. The Laws of the Multiplication of Species The theory of the multiplication of species is central to Bacon’s of nature. He devoted much effort to the description of its principles and their applications to various phenomena in , , semiotics, per- ception, and psychology. To put it concisely, the theory states that every “active nature” issues constantly in all directions species, a stream of simil- itudes of itself. A species resembles its agent, that is, its source, “in nature, definition, specific essence, and operation” (Bacon DMS 1.1, p. 7), and makes its recipients actually like its agent. The activity of producing spe- cies is uniform: “the agent brings about the same [effect] in whatever it acts on” because “it acts by nature and therefore acts in one way” (Bacon

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CN 1.1.2.2, p. 22).7 Neither species nor their agents can exert will or deliberation; they cannot designate different species to different recipients. Therefore, there is always only one kind of species which is being pro- duced. The species thus produced is defined as corporeal, material, and natural: “a species of corporeal and material things will always have mate- rial and corporeal existence” (Bacon Perspectiva 1.6.4, p. 89). Being corpo- real and physical, the of species is temporal and finite (Bacon DMS 4.3, p. 223).8 Bacon considered the multiplication of species predictable and conform- ing to laws: “Wonderful, therefore, is the power of this multiplication, since all things hidden and revealed happen in accordance with its laws” (Bacon OM 4.4.3, p. 142).9 When he explained why an object must stand opposite to the eye in order to be seen, he stated that, the four qualities, as we indicated above in [our analysis of] the laws of multiplication (legibus multiplicationum), can complete their species just as the four elements do, owing to the necessities [of the process] of generation (Bacon Perspectiva 1.8.2, pp. 114–15). Bacon indeed hinted at a more general set of laws; he called it the “common laws of nature” or “the laws of material things,” under which the laws of multiplication fall. For example, he described five kinds of multiplication: simple, refracted, reflected, accidental, and in animated medium. When he reached the fifth kind, he stated that it is different from the others, “for it does not follow the common laws of nature, but claims for itself a special privilege” (Bacon OM 4.4.2, p. 117).10 This kind of mul- tiplication does not proceed in straight lines, but in a tortuous path. In arguing in favor of the mixing of species in the medium, Bacon declared that “species must obey the laws of material and corporeal things” (leges rerum materialium et corporalium, Bacon Perspectiva 1.6.4, pp. 86–7). It is

7. “Quod idem facit agens in quodcunque agat, ut ignis sive agat in lignum sive in tactum, quia agit per naturam et ideo agit uno modo. Quod vero agit per racionem et voluntatem potest agere multis modis et diversos facere effectus, ut deus, et angelus, et homo in rebus que fiunt a voluntate, set hec est accio naturalis pura et ideo non potest fieri nisi uno modo….” See also Bacon DMS 1.1, p. 19: “An agent naturally produces the same first effect (that is, species) in whatever it acts upon, because for its part it acts uniformly; for only an agent that possesses and acts by deliberation can, for its part, act dif- formly. But a natural agent possesses neither will nor the ability to deliberate, and therefore it acts uniformly … since nature and natural mode have the same mode [of action].” 8. For an elaborated discussion concerning species as produced in time, see Bacon Per- spectiva 1.9.3, pp. 135–45. 9. “Mira ergo potestas est hujus multiplicationis cum omnia fiant secundum leges ejus et occulta et manifesta.” 10. “Nam non tenet leges communes naturae, sed sibi vndicat privilegium special.”

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not quite clear whether the laws of corporeal things are simply the laws of the multiplication of species, or are they more general laws? But since Bacon held that the multiplication of species is at the core of natural causality, it is reasonable to assume an identity between the laws of corpo- real forms and those of species, given that one of Bacon’sdefinitions of species was “corporeal form” ( forma corporalis,BaconPerspectiva 1.9.4, pp. 140–41). Now, what are the specific laws that fall under the category, “laws of material things”? We have found seven distinct such laws concerning the species’ activity. (1) The law of preservation of force. A species travelling in a single medium proceeds in its course unless impeded: “the nature of the advancing force seeks its continuity and direction unless it is im- peded” (Bacon OM 4.3.1, p. 121).11 (2) The law of inverse proportion between force and distance. Bacon declared that every causal connection in nature is made by the force of an agent. He assumed that the agent’s force is quan- tifiable: one can receive more or less of it. The force is strongest when united and concentrated on a straight line and diminishes with distance. The length of a ray and its force are inversely pro- portional: the shorter is the ray, the stronger is its force, regardless of the unique qualities of the force: “nature works … more effec- tively in a straight line, than in curved, because it is shorter” (Bacon OM 4.3.1, p. 120).12 The for this is that equal is better than unequal, and a united force produces stronger action. In a straight line equality, uniformity, and unity are greater (Bacon OM 4.3.1, p. 120). In accordance with this principle, “a species is continuously weakened in the mundane bodies in which it is mul- tiplied,” a feature which, Bacon clarified, “falls under the law of species” (sub ratione species, Bacon DMS 4.1, pp. 206–09).13 (3) The first law of the perpendicular. It follows from law (2) that the amount of force depends upon the angle of incidence: when perpendicular, the line of force is the shortest and therefore the strongest. An oblique angle extends the line, and therefore weakens the force: “The perpendicular … is shorter; therefore,

11. “Appetit natura virtutis incedentis in continuum et directum nisi impediatur.” 12. “Natura ergo … fortius super lineam rectam quam super curvam, quia brevior est.” 13. This is in fact an early form of Fermat’s principle (1662), stating that the path taken between two points by a ray of is the path that can be traversed in the least time.

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the force coming along it will act more strongly” (Bacon OM 4.3.1, pp. 120–21).14 (4) The second law of the perpendicular. Lines passing close to the perpendicular, gather strength from this proximity: “Just as the perpendicular course is strongest, so every course close to the per- pendicular is stronger than any course more remote from the per- pendicular” (Bacon DMS 2.3, pp. 114–15). (5) The law of uniform action.15 According to this law, a ray must proceed in the direction which will most nearly preserve the same strength in the second medium as in the first: when a species passes from a subtler into a coarser substance, it maintains its ease of traversal in the second substance, so that its passage through the two substances is, in so far as possible, proportional and uniform. (DMS 2.3, pp. 114–15) This explains why a ray passing from a dense to rare medium bends away from the perpendicular (based on law 4), and a ray passing from rare to dense medium bends towards the perpendicular. (6) The law of reflection. According to this law, “the angle of incidence and reflection of a species are always equal” (Bacon OM 4.2.2, p. 114).16 Bacon did not discover this law; it is due to Euclid (fl. 300 BC).17 Bacon appealed to this law to explain the production of heat from light rays. When rays fall at oblique angles, an infinite number of rays intersect “according to the law of incidence and reflection at oblique angles” (ex lege incidentiae et reflexionis ad angulos obliquos)andheatis produced. The rays intersect since an infinite number of oblique rays issue from each point of the various agents, and then a corresponding infinite number of rays reflect in other directions due to the law of reflection. Therefore at every point on earth an infinite number of rays intersect, making the air warmer (Bacon OM 4.3.1, p. 122).18 (7) The law of refraction. This law states that the angle between the ray and the perpendicular is smaller in the denser medium than in the rarer. All transparent substances offer resistance to the multi- plication of species, and since perpendicular species are stronger,

14. “Ergo perpendicularis … est brevior; quare virtus veniens super eam operabitur fortius.” See also Bacon OM 4.3.1, p. 120. 15. This law was noted by Lindberg 1968, p. 32. 16. “Anguli incidentiae et reflectionis semper sunt aequales.” 17. For the Euclidean of the law of reflection, see Smith 2015, pp. 56–9. 18. An instance of “laws of refraction” in the plural form appears also in Bacon OM 4.2.2, p. 130.

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they are slowed down but not deflected from their original course, hence refraction does not occur (Bacon DMS 2.3, pp. 112–13). But an oblique species is impeded more strongly by the medium and according to law (4) deflects toward the perpendicular (Bacon DMS 2.3, pp. 114–15). Bacon stressed that this refraction occurs according to the law that governs passage from the subtler to the denser substance (secundum legem incessus a subtiliori in densius), by bending towards the perpendicular, so that the refracted species falls between the direct path and the perpendicular … drawn from the point of refraction (Bacon DSM 2.4, pp. 126–27). The law of refraction explains the difference in the apparent position of a star at different times. When the star is on the meridian line near the zenith of the observer, its rays fall perpendicularly and therefore do not refract. Thus the star is seen in its true position. But when the star rises its rays fall at oblique angles. The rays are refracted between the celestial sphere and the sphere of fire because these two media differ in , and vision sees by broken lines and errs in regard to the position of the star. Bacon did not attempt to provide a more exact measure for the angle of refraction, and used the rather vague phrasing of “more” or “less.” Such an attempt was made by Grosseteste who stated in De iride that a ray passing from a less dense to a denser medium will be bent towards the normal so that its path in the second medium is at an angle equal to half the angle of incidence (Grosseteste, De iride). Note that of the seven laws, Bacon explicitly referred only to (6) and (7) as lex. The rest either appear in a list which Bacon titled “canons or rules” (canones seu regulae, Bacon OM 4.3.1, p. 120), or—to our understanding— fall under the category of the general title “laws of multiplication,”“laws of species,” or “laws of corporeal things.”19 With this set of laws at hand Bacon arrived at a series of inequalities that can be applied in the calculation of force: a refracted line transmits more force than reflected line, because refraction is in the direction of the straight path, while reflection advances in the opposite direction (law 1) (Bacon OM 4.3.1, p. 121);20 however, refraction between different me- diums weakens the force more than reflection in a single medium because “the double medium impedes more than the single” (Bacon OM 4.3.1,

19. Ruby (1986) argues that Bacon used lex for the more fundamental principle of mul- tiplication, and regula or the Greek equivalent, canon, for variants under specific conditions. 20. “Reflexio multum debilitate speciem et virtutem, et magis quam fractio.”

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p. 122);21 but refraction in a second, denser body, weakens the force less than refraction in a rarer body, since according to the law of refraction (7) the line (ray) is deflected toward the perpendicular thus gathering more force (Bacon OM 4.3.1, p. 122); reflection at right angle weakens the force more than reflection at oblique angle, because reflection is in an opposite direction to the “natural effort of the species itself” (law 1), while in oblique angles the direction is not entirely opposite (Bacon OM 4.3.1, p. 122). Conversely, because in reflection at right angles there is a doubling of force at the same place, the combined action is still stronger; however, since the number of reflected oblique rays is much greater than the number of per- pendicular rays, their combined force is stronger “according to the law of incidence and reflection at oblique angles” (ex lege incidentiae et reflexionis ad angulos obliquos, Bacon OM 4.3.1, p. 122). Once he laid down these “canons or rules” (aliqui canones seu regulae), Bacon made a straightforward nomological declaration: By these principles and the like given by means of geometry, a man can verify every action of nature, because every truth in regard to the action of an agent in a medium, or on generable matter, or on celestial [matter], and on the whole machine of the world, originates mediately or immediately from the principles just stated, and from certain similar ones. (Bacon OM 4.4.1, p. 127)22 As in the case of the law of the gravity of water, the principles underlying the laws of multiplication are geometrical, namely, the relevant parameters are the length of the lines and the magnitudes of the angles. Bacon declared here that the laws of multiplication are universal, and apply wherever matter exists. Moreover, he stated that the list he produced is not exhaustive; more laws can be discovered, deriving from those already formulated or from others, similar, laws.

2.3. The Law of Universal Nature Bacon defined the universal nature as a “reigning power of the universe” (virtus regitiva universi, Bacon CN 1.2.3, p. 92), responsible for the conti- nuity, consistency, and regulation of natural bodies. He often referred to it as a “law.”23 While by virtue of their particular nature bodies move to

21. “Oportet quod duplex medium magis impediat quam unum.” 22. “His principiis et hujusmodi datis per vias geometriae, potest homo verificare omnem actionem naturae, quia omnis veritas circa operationem agentis in medium, vel in materiam generabilem, vel in coelestia, et in totam mundi machinam, sumit ortum mediate vel immediate ex jam dictis, et quibusdam similibus.” 23. It may be the case that Bacon conflated—at least as far the universal law of nature is concerned—the law itself with the actual, physical force. Logically, these two categories ought to be distinctly differentiated.

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their natural place (heavy bodies down and light bodies up), in certain circumstances they are forced to obey the higher law of universal nature, when its requirements override tendencies of their particular natures. Ac- cording to Grant (1973), the doctrine of “universal nature” was formulated in order to explain the Aristotelian maxim that “nature abhors vacuum.” This natural principle assumes thatmatternecessarilyrushesintofill places or that were in danger of becoming void. While in the ordi- nary course of events, bodies behave in accordance with their particular natures, matter also possesses, or is influenced by, a universal nature (natura universalis) which submits to a higher law. The most essential characteristic of the universal nature of matter was its inexorable tendency to preserve and maintain material continuity (Grant 1973). We have found four different instances in which Bacon appealed to the law of universal nature in explaining natural phenomena. (1) The clepsydra. A vessel with small holes at the bottom is sub- merged in water until the air is completely replaced by the incom- ing water, the opening at the top is covered by one’s thumb. Upon lifting the vessel from the water, the water remains in the clepsy- dra despite the expectation that it should flow downwards through the holes at the bottom of the vessel. The water in the clepsydra remained suspended, Bacon argued, because the universal nature works to prevent the formation of a vacuum so that the order and continuity of matter be preserved. “The water are detained above by the law of universal nature (ex lege nature universalis), in order that the continuity of natural bodies will be made, to be followed secondarily by the exclusion of vacuum” (Bacon CN 1.3.2.6, p. 224).24 Grant interprets Bacon’s argument thus: in pre- venting a vacuum, nature must choose between two undesired op- tions. Either nature compels the water to remain at rest suspended in the clepsydra, or, should it permit the water to descend, nature would make the clepsydra collapse and join its interior surfaces. The latter alternative, however, is more disruptive to nature than the former, since the collapse of the vessel would follow an apparent momentary formation of a vacuum in the vessel and thus produce two unnatural events, namely, the momentary formation of a vacuum

24. “Dicendum est quod detinetur superius aqua ex lege nature universalis, ut fiat conti- nuacio corporum naturalium, ad quam sequitur secundario, exclusion vacui.” See also p. 220: “Dicendum est quod ex lege nature universalis contrahentur latera vasis, et sequentur situm rei condensate; ut salvetur continuacio rerum naturalium, et sic per consequens excludatur vacu- um.” According to Grant this theory was formulated, probably for the first time, by Bacon and/or by the anonymous author of the Summa philosophiae, falsely ascribed to Grosseteste.

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and the collapse of the vessel. Bacon made explicit what was fre- quently only implied in the medieval theory of a universal nature: material continuity is always preserved in the least disruptive pos- sible manner (Grant 1973). (2) The generation of the elements. It is evident that the parts of each element are generable and corruptible, that is, they can be transformed by natural processes into another element. The law of universal nature ensures, however, that one element would not take over another element and transform it completely, so that none of its original parts remain: by the law of universal nature (ex lege nature universalis), it cannot be generated completely, for such generation cannot happen, except by the destruction of a large part of another element which is necessary for the world. (Bacon CN 1.4.2.1, pp. 269–70)25 The law of universal nature regulates the balance among the elements and makes sure that all four of them continue to exist. (3) The species of noble agents. Bacon set the principle that the agent’s degree of nobility determines the strength of its virtue; nobler agents, therefore, have stronger virtues, and are better able to com- plete their species.26 Since the heavens are nobler than terrestrial bodies, they are more active, and able to transform the elements through their species and render them celestial. But that would destroy all terrestrial corporeal natures and consequently the order of the universe as well: Therefore, although by the law of particular nature (ex lege nature particularis) there is aptitude on the part of … active celestial substances … through which there could be complete effects … nevertheless by divine ordination and a universal law of nature (ex lege nature universalis) … the power is withheld. (Bacon DMS 1.6, pp. 84–5). This is a most revealing passage; it appeals to a particular law as well as to the universal law. We see here explicitly how two different kinds of law—operating on different levels—work coherently in tandem to complement one another. The law of universal nature is responsible for the general equilibrium among the elements, as well as for overseeing

25. “Set ex lege nature universalis est quod non possit totum generari, nam non posset tantum generari nisi ex alio elemento destrueretur magna pars que est necessaria mundo.” 26. A species is complete when it renders its recipient similar to the agent from which it was issued.

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the balance between terrestrial elements and celestial matter. This feature makes it indeed worthy of the appellation “universal,” since it applies to all sorts of matter throughout the entire universe. (4) Death. Universal nature does not permit brute animals to be im- mortal, because corporeal nature determines a place for them, and if they would be immortal, the place in the world would not suffice, nor will the food, and men will not be able to survive (Bacon CN 1.2.3.1, pp. 92–3). All the same, the death of individual persons (with respect to the present life) is “necessary according to the law of uni- versal nature … although the particular nature of this or that individ- ual is not directed towards corruption, but towards life and health” (Bacon DMS 1.6, pp. 86–7).27 The particular nature of each individ- ual strives toward its health and survival, but the law of universal nature overrides this effort. It does so for the greater good of both men and animals, and of nature as a balanced and moderated system. We can now appreciate that the law of universal nature is not only about the abhorrence of vacuum, as Grant suggested. Rather, the application of the law of universal nature and its governance uphold for all elemental and celestial matter, animate and inanimate beings. It administers , generation and corruption, life and death. If one wishes to speculate about the sources of Bacon’s idea of the universal law of nature, we may point to several candidates. Bacon’s inspiration for this law could have come from , who remarked in the Rhetoric: By the two kinds of laws I mean particular law and universal law. Particular law is that which each community lays down and applies to its own members: this is partly written and partly unwritten. Universal law is the law of Nature. For there really is, as everyone to some extent divines, a natural justice and injustice that is binding on all men, even on those who have no association or covenant with each other. (Aristotle Rhetoric I.13, 1373b4-8) To be sure, Aristotle’s universal law is a moral law; indeed, the quote is not from his corpus of . Schramm (1981) traces the concept of universal law to ’s Sufficientia. Ruby (1986) argues for yet another source; in her view, the phrase could not have come from Avicenna, but per- haps from Gundisalvis’s twelfth century of that text. She also claims that the phrase “law of universal nature” cannot be the source of the “laws of nature” in Bacon’soptics.

27. “Necessaria est ex lege nature universali … licet natura particularis istius vel illius non intendat corruptionem, sed vitam et salute.”

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While the concept of “universal nature” as opposed to the particular na- tures has several precedents in the history of philosophy, Bacon was appar- ently the first to turn that concept into a “law.” Bacon himself declared that the source of the concept was Avicenna’s 6 (Bacon CN 1.1.2.2, p. 21),28 yet on another occasion he noted that the source was : And this can be understood in two ways, or that the active quality is given to water or air by the agent accidentally… or, even though they have those [active qualities] from creation, yet they … are not active nor are they made to be active as long as they remain pure…. For their active potency is restrained by a stronger virtue, that is, by the virtue of universal nature, which intends the prosperity of the spheres of the elements and of those living in them, according to Averroes 2 De anima. (Bacon CN 1.4.2.1, p. 273)29 Bacon discussed here two options: either the elements are inherently passive, or inherently active. He rejected the first option (which is not consistent with his theory of the multiplication of species), but then he had to explain why the elements do not always act in accordance with their nature. Following Averroes, Bacon suggested that the universal nature is a power or force which, in some cases, restrains the ability of the elements to display the activity characteristic of their nature. Bacon moved on immediately to his favored example of the clepsydra, in which the water’s nature is restrained by the stronger force of the universal law: And it is similar concerning water contained in a vase perforated at the bottom, which do not fall down when the [upper] opening is blocked. For its active and moving power of quantity is restrained by the law of universal nature, which does not allow vacuum. (Bacon CN 1.4.2.1, p. 273)30

28. “Et ex ordinacione divina et ex lege nature universalis, que intendit salutem tocius mundi, quam Avicenna sexto Methaphisice vocat naturam diffusam in substanciam celorum et omnes partes universi, que est natura in qua conveniunt omnia.” 29. “Et potest hoc duobus modis intelligi, vel quod data sit aque agenti vel aeri qualitas activa accidentaliter … aut licet habeant eas ex creacione, tamen non agunt nee nata sunt agere dum remanent in sua puritate…. Nam ligatur eorum potencia activa per forciorem virtutem, scilicet, virtutem nature universalis, que intendit salute sperarum elementarium et | habitancium in eis, secundum Averrois 2 De Anima.” 30. “Et est simile de aqua contenta in vase perforato in fundo, que non descendit quando orificium obstruitur. Nam potencia sue quantitatis activa et motiva ligatur ex lege nature uni- versalis que vacuum non patitur…. Set stelle excitant qualitatem aque activam, et intendunt earn et augmentant, et tune quia exit naturam propriam, agit in terram locatam a se et in aerem…. Nee hoc est per naturam loci … set in quantum transcendent hanc naturam.”

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Two things are noteworthy here: first, the explicit allusion to Averroes as the source of the idea of universal nature; secondly, the reference to the uni- versal nature as a virtue. Bacon considered both the universal nature and spe- cies virtues and, once again, a calculus of virtues or forces is at the foreground; the stronger virtue overpowers the weaker one. The comparison of forces features in almost all the laws of the multiplication of species; such a com- parison is apparent here too. Grant (1973) raises the question whether the universal nature is consid- ered an intrinsic property of matter, or a separately existing agent acting on bodies from without? He tends towards the second option, namely, that it was conceived as an independent entity acting on bodies externally. We submit that the repeated reference to the universal nature as a power or virtue which withholds and restrains the natural tendencies of active agents can determine this issue: while particular natures are intrinsic to matter, the law of universal nature is an expression of a separate, external force acting from without. But where does this force come from? Bacon answered that the universal nature is “diffused by the heavenly substances through all the bodies of the world” (Bacon CN 1.2.3.1, p. 92).31 This idea is reminiscent of astrological beliefs; hence Thorndike’s assertion that be- fore Newton’s universal law of gravitation, there was a different generally recognized universal law, which was astrological (Thorndike 1955). However, in spite of the fact that the universal law of nature is not in- herent to the elements, Bacon considered the law corporeal: the universal law is “a corporeal nature, designated to the second genus, which is a body” (Bacon CN 1.2.3.1, p. 92).32 Once universal nature is defined as corporeal, it follows that it is also finite, namely, operates in time: “and the universal nature is a finite power, it therefore operates in time and not in an instant” (Bacon CN 1.3.2.6, p. 221).33 However, it is one thing to say that the species are corporeal, and quite another to say that the laws regulating their conduct are corporeal as well.

3. The Interrelatedness of Laws of Nature: A Hierarchy In his introduction to the volume on the philosophical, scientific and his- torical dimensions of the concept of law of nature, Weinert states that “laws should not be regarded in isolation. Because of the fundamental interrelatedness of the physical world, laws, too, are interrelated” (1995,

31. “Diffusa in substancias celorum per omnia corpora mundi, et est in quo omnia cor- pora convenient.” 32. “Natura universalis est natura corporalis que per secundum genus, quod est corpus, designature.” 33. “Et natura universalis est virtutis finite, ergo operatur in tempore et non in instant.”

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p. 21). In this vein we examine whether Bacon’s three kinds of laws of nature are indeed interrelated and, if positive, in what ways? On the face of it, there appears to be a tension between the particular and the universal in how Bacon developed his scheme of laws of nature. Bacon introduced a plurality of laws in an increasing level of generality. The par- ticular laws of water and the stars are in many ways a part of the Aristotelian . Particular nature characterizes each of the four elements; the law of the gravity of water is one example of this. However, the law is not simply of an Aristotelian nature; it has the additional feature of geomet- rical substantiation, with the geometrical properties turned into causes. As- trological lawfulness is particular in the sense that each star has its own unique “law.” These “laws” are not on a par with the Aristotelian “natures”; they signify occult and moral symbolic states, with no bearings on natural philosophy. The laws of multiplication of species are more general, applied to the four elements, to celestial matter, and to the way by which the var- ious stars influence earth. Bacon did not state clearly the relation between the laws of species and those of particular nature. It would appear that as far as the activity of species is concerned, all agents act the same; their partic- ular nature is irrelevant. No clash between a particular law and a law of species is recorded. However, both rely on the power of geometry and geo- metrical properties are considered to be their cause. The most general law is the law of universal nature, which, as indicated, can overcome the tendencies of the laws of particular natures: the law pre- vents the water from falling down when the threat of vacuum is imminent; and it hinders the particular tendency of animate beings to preserve their existence forever. It can also restrain the laws of multiplication of species: it does not allow the species of celestial bodies to turn elemental matter into celestial matter. What seemed to be a tension among the different catego- ries of laws is thereby resolved. Each set of laws has its own well-defined function: the particular laws are meant to account for the unique features of a certain group of beings, while the laws of multiplication account for the common features of mat- ter. Put differently, the laws of particular natures regulate the conduct of individuals and species; the laws of the multiplication of species regulate how individuals affect one another physically. Finally, the law of universal nature regulates those interactions and brings them back to balance when necessary. It is a sort of mechanism of control and supervision which makes sure the system keeps working and all of its components play their parts well; hence the expression machina mundi.34

34. For this expression, see Hon and Goldstein 2008, pp. 122, 158, 159 fn. 6.

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The common feature of the laws of multiplication and the law of universal nature is that their subject matter is force. Bacon seems to hold that most physical phenomena can be reduced and explained by appealing solely to the concept of force. He stated the principle, which is apparently absent from Alhacen (c. 965–1040)—his principal inspiration for the laws of optics— that nature acts more strongly in a straight than in a curved (reflected or re- fracted) line (Lindberg 1968). This claim can be understood as a universal statement about forces in general, and not about optics alone. It is indicative that Bacon defined the law of universal nature as a “virtue,” namely, a force. This enabled him to add it to his calculus of forces or species (which he also defined as “virtues”). No wonder that he described the universal law as cor- poreal; otherwise, how could it interact with the corporeal species? All these are forces, and the universal law governs the strongest of the forces. It overpowers both the laws of particular natures (as shown in the case of the clepsydra) and the laws of multiplication (as shown in the case of the species of celestial nature). It emerges then that this system of laws displays a hierarchy of laws which is organized according to degree of generality: from the particular and the specific, to the most general and thus the most powerful. The ordering principle is then the intensity of the governed force. Another way to consider the interrelatedness of the laws is to order them on a different principle: each type of law expresses a different cate- gory of cause. The laws of particular nature account for the formal causality of natural change. In the case of water, the law of the particular nature of water answers the question of what it is to be water, to be humid and to flow down towards the center of earth. The form determines the typical activities we observe in the world. The form of water characterizes water only, and its corresponding law provides the of its behaviour in different circumstances, given its unique definition and characteristics. The species in Bacon’s philosophy of nature are identified with a physical force responsible for all efficient causality in the universe. In the Communia naturalium Bacon declared: I hold that two things drive to the production of things, that is, the efficient cause and matter. Now it ought to be proceeded about the efficient cause as much as required, because Metaphysics has to fully certify concerning the influence of the agent upon the patient, that which all operations in sense and intellect and the matter of the world are made by influences of this kind, namely, the aforementioned [entities] which are called species. (Bacon CN 1.1.2.1, p. 16)35

35. “Habito quod duo exigantur ad rerum produccionem, scilicet, efficiens et materia, nunc procedendum est circa efficiens quantum hie requiritur, quia Metaphisica habet cer- tificare ad plenum de influencia agencium in paciencia, eo quod omnis operacio in sensum

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In Bacon’s philosophy of nature the influence of the agent upon the patient is made through species. This influence drives the patient to action; it is therefore exactly what Aristotle would have called “efficient causality.” Accordingly, Bacon added in the De multiplicatione, “all judges that through species [all] other effects are produced” (Bacon DSM 1.1, p. 7). The laws regulating the species’ activity are therefore the laws of efficient causality. In contrast to the laws of particular natures, the species’ causal power originates not in the specific qualities they govern, but in their inherent activity and their participation in the flow of force. This is the reason why general laws can be formulated concerning their governance of a variety of phenomena. We turn now to the most general law. The law of universal nature ex- presses nature’s final cause: just as the final cause of each being taken sep- arately is its prosperity and well-being, so nature’s final cause is the general prosperity of creation, achieved through the maintenance of order, conti- nuity, and equilibrium among the various constituents of nature. This is exactly the function of the law of universal nature. Two different yet complementary ordering principles hold Bacon’s sys- tem of laws together. It is an expression of a well-designed hierarchy. The classification reflects a move: (1) from the particulars to the most general, and this move covers all causes, and (2) from the formal through the effi- cient and to the final. It is striking that the same hierarchy of laws can capture two different ordering principles. It is a mark of Bacon’sextra- ordinary to successfully a system of laws based on degree of generality with an embedded complete set of causes.

4. The Significance of Bacon’s System of Laws of Nature Does Bacon’s conception of law of nature and the associated terminology indicate a significant change from the dominant Aristotelian conceptuali- zation of nature? When Bacon added the term “law” to the old idea of “universal nature,” how did it affect the understanding of what a “universal nature” is? When he attached “law” to the old principles of reflection and refraction, what, if at all, was achieved? Are these laws something like “regularities we have observed,” or prescriptions that nature must obey? Are they qualitative or quantitative? And what exactly do these laws ex- plain? In seeking answers to these questions, we build on Weinert’s (1995) study, from which we draw five of the six criteria listed below. The sixth is an addition of our own: (1) if/then formulation; (2) counterfactuals; (3) in- dependence of space-time; (4) explanatory power; (5) systemacity; and (6)

et intellectum et materiam mundi fit per hujusmodi influencias, scilicet, predictas que vocantur species.”

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quantitative aspect. Weinert formulated these criteria in order to distin- guish laws of nature from accidental regularities; we will use them, however, as a vehicle to characterize Bacon’slaws. Weinert’s (1995) first criterion is that laws can be expressed as if/then statements: if certain physical conditions are satisfied, then certain events follow. In addition, a law of nature must not simply sum up the occur- rences of , but cover non-existing future situations as well. Bacon’s laws comply with both requirements. Consider the law of refraction; it can be rephrased as follows: if an oblique ray passes from a rare medium to a denser one, it will deflect towards the perpendicular. Bacon himself performed an if/then exercise regarding the consequences of the law of reflection: It is possible to assemble an infinite number of rays by reflection … so that strong combustion will be made…. If, therefore, a concave spherical be placed against the sun, an infinite number of rays will meet at one point by means of reflection. And therefore it is necessary that fire be ignited when a concave mirror is placed against the sun…. (Bacon OM 4.2.2, p. 115)36 From the if/then exercise, it is clear that the law of gravity of water and the laws of species cover future events, not only past ones, and this is true for the law of universal nature as well, which predicts that natural continuity will be preserved in the future too. According to Weinert, true laws support counterfactual situations: in case of a deviation from the law, it can be stated how the physical world would change. With some caution, this may be true of Bacon’s laws as well. Consider for example the following quote concerning the law of refraction: All doubt is resolved by the law of refraction (legem fractionis). For three things are required for refraction, namely, that the second body would have a surface distinct from the first, and that it be of a different rarity … and that the rays would fall at oblique angles. But if one of these conditions is lacking, refraction is not possible. (Bacon OM 4.4.2, p. 132)37

36. “Possunt autem congregari radii infiniti per reflexionem … ut fiant combustions validate…. Si ergo speculum concavum sphaericum ad solem ponatur, concurrunt radii infiniti in punctum unum per reflexionem. Et ideo oportet, ut speculo concavo ad solem posito ignis accendatur.” 37. “Et tota dubitatio solvitur per legem fractionis. Nam tria requiruntur ad hoc ut sit fractio, scilicet ut corpus habeat superficiem distinctam a primo, et quod sit alterius raritatis … et quod radii cadant ad angulos obliquos. Quod si aliquid istorum deficiat, non est fractio possibillis.”

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These are the necessary requirements for the phenomenon of refraction to take place, and if these requirements were to be revoked, then so would refraction. The law of universal nature does not stand up to this criterion, since no inversion of facts would change or annul it. This law would last as long as the material world lasts, regardless of its composition and structure. Weinert’s next criterion is that laws must have some explanatory power (although in most cases explanations of phenomena are obtained from laws in conjunction with a theory). It would appear that all the laws dis- cussed in this paper have an explanatory role. The law of the gravity of water explains the phenomena of the communicating vessels, and why water contract as they get close to the center of earth; the laws of multi- plication of species explain action at a distance, the formation of heat, the tide (Kedar 2016), mirror images, and various other optical phenomena; and, finally, the law of universal nature explains why water remains in the clepsydra. Law statements, Weinert continues, should make no reference to spe- cific space-time coordinates. This is the condition of universality which requires that law statements abstract from particular boundary conditions to capture the structure of the physical system. All of Bacon’s laws comply with this requirement: the law of gravity of water is limited in space, since it refers only to water in relation to earth; however, according to the con- temporaneous , earth was the center of the universe, and thus the law applies to water wherever they are around the universe; they will always be drawn to its center. Our difficulty here is the sheer fact that the universe has a center, namely, that space is not homogenous. The laws of multiplica- tion of species, however, truly lack space-time limitations. Species are issued wherever and whenever matter exists, whether elemental or celestial, at the center of the universe or at its edge. Finally, the universality of the law of universal nature needs no substantiation with respect to this criterion. The last of Weinert’s criteria to be discussed here is that of systemacity; a statement would count as a law if it were embedded in a network of statements which are interrelated to each other. The relation is inferential, and one of the most important inferential relations is that of derivability. Systemacity as derivability can be found in the relations among the laws of multiplication of species. As shown above, the first law of the perpendic- ular (3) derives from the law of inverse proportion (2); the law of uniform action derives in part from the second law of the perpendicular (4); the law of refraction derives from the law of uniform action (5) and from the first law of the perpendicular (3), which explains why perpendicular rays do not refract. The laws of multiplication of species, as well as the law of the grav- ity of water, do not derive from the law of universal nature and not from

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each other. But that does not mean they do not form a system. As we have shown, there are relations of subordination and order among these laws, in which one overpowers the others. In this sense, Bacon’s laws are all part of one system; indeed, this is one of the conspicuous traits of Bacon’s concep- tion of nature. Some of his laws were of course not his own (reflection and refraction were discussed by Euclid, Ptolemy (c. 100–170 AD), Alhacen and Grosseteste); Bacon, however, entitled them “laws” and included them within one system along with other laws. He found a common denomina- tor between refraction and the gravity of water: both were laws that govern nature. We see that with the appellation “law,” Bacon endowed the princi- ples of reflection and refraction with a non–temporal application, and thus rendered them true of future situations as well. In this way, he stressed their necessary and universal aspects. The title “law” calls for a network, a system; had this title been given only to the universal nature or to reflection, it would not have been a significant move. However, calling “law” the uni- versal nature, the multiplication of species, as well as the particular natures, and setting these laws in relations of derivation and subordination, do create a system. This is a significant move on the part of Bacon. The last criterion we need to examine in order to fully characterize Bacon’s laws is whether these laws were quantitative. Note that even mod- ern laws of nature need not necessarily be quantitative; Newton’s first and third laws of motion, for instance, were not quantitative. Among Bacon’s laws, the law of universal nature and the law of preservation of force were clearly qualitative. But even the laws that do appear quantitative, as they compare angles and amounts of force, are not truly so. As Lindberg (1968) notes, Bacon made no pretense of having engaged in actual measurements. Lindberg touches here one of the most distinctive features of Bacon’s laws: he made no attempt to formulate them quantitatively. Except for the law of reflection, which states equality, Bacon’s laws cannot be translated into mathematical formulas. “More” or “less,”“smaller than” or “larger than” cannot be used for actual calculations since it does not provide equalities, constants, units, or definite numbers whatsoever. The laws are quantitative in the sense that they compare amounts of force, and state geometrical properties as causes for physical events, but they are not mathematical. Although Bacon claimed that by using his laws one can predict how nature behaves, there is no way in fact to calculate on the basis of the law of the gravity of water the measure of the water’s contraction in the lower cup relative to the water in the higher cup, or to state—based on the law of refraction—the angle by which a ray deflects upon entering a denser body. The intriguing point is that although the laws had no practical imple- mentation, Bacon did not think they were speculative. In the Communia

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mathematica, he explained the difference between astrology and astron- omy. His explanation reveals an important aspect of his conception of lawfulness: But astrology is composed from the name “astrum” which is a “star,” and the name “logos” which is a “word” or “ratio” or “sermo” because it is a talk about the stars; is indeed said to be the law of the stars and “nomos” is “law,” hence because law universally reads in practice, as in moral philosophy law is itself practical, so similarly astronomy is practical astrology (Bacon CM, p. 39).38 The search for laws belongs, according to Bacon, to the practical part of science as opposed to its speculative part. While astrology according to Bacon is a science dealing with theories, astronomy derives laws from these theories. The attribution of laws to the practical is reinforced a few pages later: And from this it is clear, that the speculative of these sciences ought to be called astrology, for the Greek “nomos” is the “lex,” and therefore astronomy is a science of the laws of the stars; and the Greek “logos” is “sermo,” due to which astrology is a discourse about the stars. But “law” predominates over discourse, because law is included under discourse, it is not dealt with except by discourse, and moral law is the practical part of political science, as is clear from the end of Aristotle’s book of Ethics, similarly, the law of the stars will be echoed in practice. Whence it comes down to particulars much more than the universal discourse concerning the stars, and therefore astronomy, much more than astrology is allotted a practical nature. (Bacon CM, p. 50)39 Astronomy is a practical science because it formulates laws; laws come down to particulars: they are “echoed in practice.” These pronouncements are not a mere lexicographical exercise; indeed, they raise an immediate

38. “Sed Astrologia componitur ex hoc nomine ‘astrum’ quod est ‘stella’ et hoc nomine ‘logos’ quod est ‘verbum’ vel ‘ratio’ vel ‘sermo’ quia est sermo de stellis; Astronomia vero dicitur lex stellarum et ‘nomos’ est ‘lex’, unde quia lex universaliter sonat in practicam, ut in Moralis Philosophia lex est ipse practica, ita similiter Astronomia est practica Astrologie.” 39. “Et ex his patet quod speculative hujus scientie debet nominari Astrologia, et ejus practica Astronomia, nam ‘nomos’ Grece est ‘lex’ Latine, et ideo Astronomia est Scientia de legibus astrorum; et ‘logos’ Grece est ‘sermo’ propter quod Astrologia est sermo de astris. Lex autem habundat super semonem, quia lex infra sermonem includitur, non enim trac- tatur nisi per sermonem, et lex moralis est de practica parte civilis scientie, ut patet ex libro Ethicorum Aristotelis in fine, similiterque, lex astrorum in practicam resonabit. Unde ad particularia magis descendit quam sermo universalis de astris et ideo Astronomia magis quam Astrologia naturam practice sortietur.”

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puzzle, namely, why would Bacon consider laws to be practical? Bacon provided a partial answer: astronomy deals with particulars and is therefore much more practical than a science which is a “universal discourse concern- ing the stars,” that is, astrology. Bacon committed then the laws of nature to the practical part of sci- ence. This position reveals an interesting aspect of Bacon’s understanding of laws of nature. Lehoux (2012) draws a distinction between two closely related senses of “law of nature”: (1) laws portray nature as always behaving in certain ways, and (2) laws offer mathematical formula for calculating what should be expected from nature, that is, to solve unknowns in natural systems. Evidently, Bacon conceived his laws within the framework of the second category, that is, prediction, for he formulated the laws in the prac- tical domain of science. In Bacon’s view, laws are not theoretical constructs, but the highway to improving human’s life. He declared on several occa- sions that it is important to know the laws in order to perform works for the enhancement of human lives. He considered optics, the very science of the laws of the multiplication of species, as practical, and wherever he stated an optical law a list of several applications would follow. Bacon argued that knowledge of optics, particularly of the rules of reflection and refraction of light, can help Christendom defend itself against its enemies. For example, shaping a mirror so that one group of soldiers will appear from a certain angle as multiplied, would terrify the enemy (Bacon Perspectiva 3.3.3, pp. 330–33). Bacon’s laws are presumed to translate the general discourse about nature into well-defined rules and practices. This might have been Bacon’s goal. However, he did not succeed in achieving this goal, and it seems that Bacon’s system of laws be classified better under Lehoux’s first category, that is, that of laws of nature which tell us how nature generally behaves.

5. Conclusion We presented in this paper an unusual scene in the , a thinker from the thirteenth century who explicitly used the phrase “laws of nature” (also of “material things,”“material forms,” and of “multiplica- tion”) in the genitive form; who invoked this expression consistently with respect to a variety of phenomena and on many levels; who did not only state in general that such laws exist, but actually formulated a few of them and indicated their possible applications. If this is not enough, the laws he formulated share many features in common with the early modern concept of law of nature. For example, many of Bacon’s laws can be restated as if/ then sentences and all of them cover future events, some support counter- factuals, and they are all endowed with explanatory power and free from space-time limitations.

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Weinert argues that all genuine laws bestow epistemological priority on physical systems over individuals. Indeed, Bacon’s laws, considered together, do form a system, in which some laws derive from others and some are ordered in relations of subordination. The laws of particular natures account for some of nature’s regularities; they explain them as detached from other factors. The laws that bind nature together are those of the multiplication of species; and at the top of the hierarchy of laws, there is the overriding law, namely, the law of universal nature which preserves nature’s well-being. A manifold of phenomena is accounted for with this system. The system unites nature and keeps it in balance. The scheme of different levels of laws covers three aspects of Aristotelian causality: formal, efficient, and final.40 A complete explanation, Aristotle maintained, requires that all three be accounted for. It is thus only together that these laws can provide a sufficient explanation for natural events. Bacon declared, however, that the search for laws had not been completed, and more laws can be derived from the ones already discovered. Therein he stated that the scientific effort is an ongoing project, and that its goal, among other things, is to discover and formulate laws of nature. In Bacon’s eyes, the search for laws is not a theoretical endeavor for it has a definite practical goal—to enhance human life. Of all the laws Bacon prescribed, the unique and most surprising to the modern mind, is the law of universal nature: it is prescriptive, has no quan- titative aspects, no counterfactuals, it is vague and general, and does not specify any connection between variables. This is certainly not a law in any modern sense. Yet it plays a crucial function in Bacon’s system of laws of nature. What is then the function of this law in Bacon’s view of the make- up of nature? The law of universal nature governs the continuity of matter and controls its order and the equilibrium among its parts. In fact, the law ensures that nature will continue to run its course unfailingly; that nature’s inner constitution and basic mechanisms will remain the same. Hence, the law of universal nature guarantees that the future will be no different from the past. In conclusion, we propose that Bacon’s law of universal nature is akin to the principle of uniformity of nature of (1711–1776), which must be true if one wants to argue that causal connections hold for future events and not only sum up past experiences. Without the principle of uniformity of nature, a conception of laws of nature is impossible, since an essential element of the concept of law requires that the law covers

40. An interesting question can be thus formulated, namely, can the material cause, responsible for individuation, be recast into a law?

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future occurrences. Thus, the law of universal nature becomes a meta- physical axiom, which is necessary for upholding the very notion of a na- ture governed by laws. The law of universal nature indicates that Bacon sought a conception of an orderly and predictable nature. He presented his readers with a conception of a lawful nature and offered a profound insight of what it takes for nature to be lawful.

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