## 1. Introduction



In the introduction to his recently completed translation of *Wars
of the Lord*, Feldman suggests that the significance of Gersonides
lies in his emphasis upon "religious rationalism in
Judaism." According to Feldman, we see a man who "has
taken seriously the fact that he has reason, who believes that this
faculty is God-given, and who attempts to understand God with this
instrument" (*Wars*, p. 52). Gersonides is the
philosopher who attempted to show that philosophy and Torah, that
reason and revelation are co-extensive; he is a philosophical optimist
who believes that reason was fully competent to attain all the
important and essential truths. Thus, according to Feldman, Gersonides
is "a most vigorous and consistent defender of human reason in
religion"(*Wars*, p. 53).



This trust is reflected in Gersonides' introductory remarks to
*Wars*. There, Gersonides upholds the primacy of reason,
attributing to Maimonides the position that "we must believe
what reason has determined to be true. If the literal sense of the
Torah differs from reason, it is necessary to interpret those passages
in accordance with the demands of reason" (*Wars*, p.
98). Gersonides believes that reason and Torah cannot be in
opposition: "if reason causes to affirm doctrines that are
incompatible with the literal sense of Scripture, we are not
prohibited by the Torah to pronounce the truth on these matters, for
reason is not incompatible with the true understanding of the
Torah" (*ibid.*). Thus reason is upheld as a criterion
for achieving truth.


## 2. Biography



Gersonides left few letters and does not talk about himself in his
writings; nor is his life discussed at great length by his
contemporaries. Hence, what is known of his biography is sketchy at
best. Levi ben Gerson was born in 1288 in Provence and may have lived
for a time in Bagnol sur-Ceze. It is probable that his father was
Gershom ben Salomon de Beziers, a notable mentioned in medieval
histories. With the decline of Spanish Judaism in the thirteenth
century, Provence quickly became the cultural center for Jewish
intellectual activity. The popes in Avignon had a lenient policy
toward the Jews, whose creative life flourished, particularly in
philosophy and theology. Jewish philosophers did not have direct
access to the works of Aristotle, but Provencal Jews learned of
Aristotle through the commentaries of Averroes, the twelfth-century
Spanish Muslim philosopher. By the end of the thirteenth century these
commentaries had been translated from Arabic into Hebrew, and
Averroes' thought, as well as that of Aristotle, was being
integrated into the mainstream of Jewish philosophy.



Gersonides may have married a distant cousin; it is not known whether
he had any offspring. Although Gersonides spoke Provencal, his
works are all written in Hebrew, and all of his quotations from
Averroes, Aristotle, and Moses Maimonides are in Hebrew as well. He
may have had a reading knowledge of Latin; he appears to manifest an
awareness of contemporary Scholastic discussions. He might, however,
have learned of such discussions in oral conversations with his
Christian contemporaries. Apart from several trips to Avignon,
Gersonides most likely resided his entire life in Orange. There is
some evidence that he may have followed the traditional occupation of
his family, moneylending. He died on 20 April 1344.



In addition to Averroes and Aristotle, Gersonides was influenced by
Moses Maimonides, his greatest Jewish philosophical predecessor.
Gersonides' works can be seen as an attempt to integrate the
teachings of Aristotle, as mediated through Averroes and Maimonides,
with those of Judaism. In *Milhamot Ha-Shem* he laid down the
general rule that "the Law cannot prevent us from considering to
be true that which our reason urges us to believe." His
adherence to this principle is reflected throughout his work.


## 3. Major Works



In her recent study of Gersonides' science, Glasner notes that
Gersonides "stands out as one of the more creative and daring
figures in the medieval west" (Glasner 2015, p. 13). What
distinguished Gersonides from his predecessors was his reliance upon
and consummate knowledge of mathematics, coupled with his belief in
the accuracy of observations achieved by the use of good instruments.
Because of this rootedness in empirical observation bolstered by
mathematics, Gersonides believed that he had the tools to succeed
where others had failed. Only when he has resolved the problems in
astronomy does Gersonides apply their findings to theological
cosmology. As we shall see, Gersonides' theology and astronomy
are deeply involved with each other.



This realist stance is stated in the context of examining
al-Bitruji's astronomical proposals. Gersonides'
contention is that "no argument can nullify the reality that is
perceived by the senses, for true opinion must follow reality but
reality need not conform to opinion" (Goldstein 1974, p. 24).
That Gersonides clearly considered his own observations to be the
ultimate test of his system is explicit from his attitude towards
Ptolemy. The importance of empirical observation cannot be
underestimated, he claims, and he values his own observations over
those of others. "We did not find among our predecessors from
Ptolemy to the present day observations that are helpful for this
investigation except our own" (*Wars*, V.1.3, p. 27), he
says in describing his method of collecting astronomical data. Often
his observations do not agree with those of Ptolemy, and in those
cases he tells us explicitly that he prefers his own. Gersonides lists
the many inaccuracies he has found trying to follow Ptolemy's
calculations. Having investigated the positions of the planets, for
example, Gersonides encountered "confusion and disorder"
which led him to deny several of Ptolemy's planetary principles
(Goldstein 1988, p. 386). He does warn his colleagues, however, to
dissent from Ptolemy only after great diligence and scrutiny. Both
John Buridan and Gersonides took the first steps in the 14th century
toward a principle of inertia; in the words of Touati, Gersonides was
the first to "have a presentiment of the principle of
inertia" (see Touati 1973, pp. 103, 311). Glasner supports
Touati's contention, claiming that "Gersonides had a
rudimentary, not yet correct, but insightful understanding of the
concept of inertial motion." Gersonides was aware of its
significance and used it in order to lay the basis for a new physics,
an alternative to that of Aristotle. (see Glasner 2015, p 36) He did
not rely on a theory of impetus [as did Buridan], which turned out to
be an advantage.



Gersonides' scientific works comprise mathematics and astronomy.
His *Sefer Ma'aseh Hoshev* (*The Work of a
Counter*, 1321) is concerned with arithmetical operations and uses
of a symbolic notation for numerical variables. Gersonides'
major scientific contributions were in astronomy; his works were known
by his contemporaries and influenced later astronomers. His
astronomical writings are contained primarily in book 5, part 1 of
*Milhamot Ha-Shem*. In 136 chapters Gersonides reviews and
criticizes astronomical theories of the day, compiles astronomical
tables, and describes one of his astronomical inventions. This
instrument, which he called *Megalle 'amuqqot*
(*Revealer of Profundities*) and which was called *Bacullus
Jacobi* (*Jacob's staff*) by his Christian
contemporaries, was used to measure the heights of stars above the
horizon. The astronomical parts of *Milhamot Ha-Shem* were
translated into Latin during Gersonides' lifetime. One of the
craters of the moon, *Rabbi Levi*, is named after him.



Gersonides was well known as a Halakhist, one who deals with the
intricacies of Jewish law. From this respect, his greatest
contribution to Judaica was in the area of biblical commentary. His
commentary on the Book of Job, completed in 1325, proved to be one of
his most popular works and was one of the earliest Hebrew books to be
published (in Ferrara, 1477). The commentary, which complements book 4
of *Milhamot Ha-Shem*, is concerned with the problem of divine
providence. Each of the characters in the Book of Job represents a
different theory of divine providence; Gersonides' own position
is a restatement of Elihu's theory that providence is not
directed to particulars but rather to groups of individuals, or
universals.



Gersonides also wrote a logical treatise, *Sefer Ha-heqesh
Ha-yashar* (*On Valid Syllogisms*, 1319), in which he
examines problems associated with Aristotle's modal logic as
developed in the Prior Analytics. This treatise was translated into
Latin at an early date, although Gersonides' name was not
attached to it.



Gersonides' major philosophical work, *Milhamot Ha-Shem*,
was completed in 1329; it had been twelve years in the making. In 1317
Gersonides began an essay on the problem of creation. This problem,
which has vexed Jewish philosophers since Philo Judaeus, had recently
received elaborate treatment by Maimonides. Gersonides was
dissatisfied with Maimonides' discussion and proposed to reopen
the issue. This project was soon laid aside, however, for he felt that
it could not be adequately discussed without proper grounding in the
issues of time, motion, and the infinite. By 1325 his manuscript had
developed to include discussion not only of creation but also of
immortality, divination, and prophecy. By 1328 it included a chapter
on providence as well. Books 5 and 6 were completed, by
Gersonides' own dating, by 1329.



As Isaac Husik has pointed out, Gersonides "has no use for
rhetorical flourishes and figures of speech ... the effect upon
the reader is monotonous and wearisome." His style has been
compared to that of Thomas Aquinas and even of Aristotle in its use of
a precise, technical vocabulary which eschews examples. In
contradistinction to Maimonides, who introduced allegory, metaphor,
and imprecise language into his work to convey the ambiguity of the
subject matter, Gersonides saw it as his function to elucidate the
issues as clearly as possible. Gersonides is the first Jewish
philosopher to use this analytic, scholastic method.


## 4. Major Themes in *Milhamot Ha-shem*



In the introduction to *Milhamot*, Gersonides specifies six
questions which he hopes to examine: Is the rational soul immortal?
What is the nature of prophecy? Does God know particulars? Does divine
providence extend to individuals? What is the nature of astronomical
bodies? Is the universe eternal or created? Each question occupies a
separate book. Gersonides attempts to reconcile traditional Jewish
beliefs with what he feels are the strongest points in
Aristotle's philosophy. Although a synthesis of these systems is
his ultimate goal, philosophy often wins out at the expense of
theology.



Gersonides' attitude toward previous astronomers, coupled with
his faith in human reason, are reflected in his discussion of
creation. Maimonides went to great lengths to maintain that the topic
of creation is beyond rational demonstration. Gersonides, on the other
hand, devotes many chapters in *Milhamot* VI to proving that
the Platonic theory of creation out of an eternal formless matter is
rationally demonstrable. The question of whether the universe was
created or had existed from eternity had been treated by Maimonides in
an ambiguous manner; scholars still disagree over whether Maimonides
ultimately upheld an Aristotelian, Platonic, or scriptural doctrine of
creation. Gersonides' position is unambiguously Platonic.
Gersonides argues that the world was created outside of time by a
freely willing agent. He must then decide whether the world was
engendered *ex nihilo* or out of a preexistent matter. Arguing
that *ex nihilo* creation is incompatible with physical
reality, he adopts a model drawn from Plato's *Timaeus*.
Gersonides interprets the opening of Genesis to refer to two types of
matter. *Geshem* is the primordial matter out of which the
universe was created; not capable of motion or rest, it was
characterized by negation and was inert and chaotic. This matter is
identified with the primeval waters described in Genesis.
*Homer* is prime matter, in the Aristotelian sense of a
substratum always aligned with form. It contains within itself the
potentiality to receive forms but is not an ontologically independent
entity. Gersonides compares this matter to darkness: just as darkness
is the absence of light, this matter represents the absence of form or
shape. As noted by Glasner (2015) and Freudenthal (1987), this notion
of a body that does not preserve its shape offered several important
advantages. First, the space between the spheres, which is subject to
continuous change, is filled by the body that does not preserve its
shape, and so transmission can be explained by contact. Second, in the
context of his theory of creation, this amorphous body is a remnant of
the pre-existent entity (thou va-vohu) from which God shaped the
world. On this basis Gersonides argues that the world was created out
of an eternally preexistent matter.



Gersonides' cosmology forms the backdrop of the other books of
*Milhamot*. His predecessor Maimonides had claimed that no
valid inference can be drawn from the nature of the sublunar sphere to
that of the superlunar sphere. Gersonides, however, rejects the
metaphysical bite to the distinction, and argues that inasmuch as both
spheres contain material elements, what we know about creation is
based on astronomy, and astronomy is fundamentally no different a
human science than physics. Astronomy can only be pursued as a science
by "one who is both a mathematician and a natural philosopher,
for he can be aided by both of these sciences and take from them
whatever is needed to perfect his work" (*Wars*, V.1.1,
p. 23). Gersonides sees the ultimate function of astronomy to
understand God. Astronomy, he tells us, is instructive not only by
virtue of its exalted subject matter, but also because of its utility
in the other sciences. By studying the orbs and stars, we are led
ineluctably to a fuller knowledge and appreciation of God. Astronomy
thus functions as the underpinning of the rest of the work.



Gersonides' discussion of immortality of the soul in book 1 must
be understood against the backdrop of a notoriously difficult passage
in Aristotle's *On the Soul*, book 3, chapter 5
(430a22-25). In this passage Aristotle seems to postulate the
existence of an active intellect which is separable from the passive
intellect and which is primarily responsible for the intellectual
activities of the human soul. But what is the relation between the
active and passive intellects, and which, if either, is immortal?
Gersonides states and rejects three positions that elucidate a version
of the unity of intellect. The import of Gersonides' critique of
his predecessors can be reduced to three main issues. From a
theological perspective, it is clear that the doctrine of unity of
intellect threatens the notion of personal immortality. For if all
humans share the same intellect, then upon physical death, all that
remains of the person is an unindividualized intellect.
Epistemologically, the doctrine is unable to account for how it is
that two (or more) knowers can entertain contrary items of knowledge;
or, more stringently, how one person can be mistaken about something
another person knows. And from a metaphysical perspective, the main
problem is how to individuate this separate intellect when it is
manifested in many individuals: for if it is individuated materially
on the basis that individual bodies differ, then the substance is no
longer incorporeal or separate. As Feldman has pointed out, on this
theory an incorporeal substance is either a unique member of a species
or is not a member of a species at all (*Wars*, I.4, p.
79).



Gersonides avoids these untoward consequences by adopting the position
of Alexander of Aphrodisias. Gersonides agrees with Alexander of
Aphrodisias that immortality consists in the intellectual perfection
of the material intellect. He disagrees with Alexander, however, over
the precise nature of this intellectual attainment. For Alexander
(according to Gersonides) had claimed that immortality is achieved
when the intellect acquires knowledge of the Agent Intellect (hence
the term "acquired intellect" is introduced). Immortality
is thus understood by Alexander to be a form of conjunction between
the Agent and acquired intellects. "They [the followers of
Alexander] maintain that the material intellect is capable of
immortality and subsistence when it reaches that level of perfection
where the objects of knowledge that it apprehends are themselves
intellects, in particular the Agent Intellect...[material
intellect] is immortal when it is united with the Agent
Intellect" (*Wars*, I.8, p. 170).



Gersonides rejects this notion of conjunction, however, and replaces
it with a model of immortality according to which it is the content of
knowledge of the acquired intellect that matters. When the content of
the acquired intellect mirrors the rational ordering of the Agent
Intellect, immortality is achieved. What is the content of this
knowledge? The Agent Intellect must possess complete knowledge of the
sublunary world; that is, it "contains a conception of the
rational order obtaining in all individuals" (*Wars*,
I.4, p. 136). The anti-Platonic tenor of this position is emphasized
when Gersonides describes in more detail what it is that the Agent
Intellect knows. For according to Gersonides, the knowledge of the
Agent Intellect must be grounded in the domain of particulars. Thus
Gersonides' position avoids the epistemological difficulties
apparent in a realist ontology. Inasmuch as the material intellect
reflects the knowledge inherent in the Agent Intellect, and inasmuch
as this knowledge is grounded in particulars, it follows that humans
can have knowledge of particulars; in this acquisition of knowledge
lies immortality.



Books 2 to 4 focus on the relation between God and the world. The
general problem is whether God's knowledge is limited to
necessary states of affairs or extends to the domain of contingency as
well. If the former, then God could not be said to have knowledge of
humans, and so divine providence would not be efficacious. But if God
does know contingents--in particular, future contingent
events--then it would appear that human freedom is curtailed by
God's prior knowledge of human actions. The problem of the
apparent conflict between divine omniscience and human freedom was
discussed by many medieval philosophers. Gersonides does not follow
the majority opinion on this issue: rather than claim that God does
know particulars and that this knowledge somehow does not affect human
freedom, Gersonides argues that God knows particulars only in a
certain sense. In an apparent attempt to mediate between the view of
Aristotle, who said that God does not know particulars, and that of
Maimonides, who said that he does, Gersonides holds that God knows
particulars only insofar as they are ordered. That is, God knows that
certain states of affairs are particular, but he does not know in what
their particularity consists. God knows individual persons, for
example, only through knowing the species humanity.



Whereas Maimonides claimed that God's knowledge does not render
the objects of his knowledge necessary, Gersonides maintains that
divine knowledge precludes contingency. To retain the domain of
contingency, he adopts the one option open to him: namely, that God
does not have prior knowledge of future contingents. According to
Gersonides, God knows that certain states of affairs may or may not be
actualized. But insofar as they are contingent states, he does not
know which of the alternatives will be the case. For if God did know
future contingents prior to their actualization, there could be no
contingency in the world.



In book 2, in an attempt to explain how prophecies are possible in a
system which denies the possibility of knowledge of future
contingents, Gersonides claims that the prophet does not receive
knowledge of particular future events; rather his knowledge is of a
general form, and he must instantiate this knowledge with particular
facts. What distinguishes prophets from ordinary persons is that the
former are more attuned to receive these universal messages and are in
a position to apply them to particular circumstances.



A further dilemma surrounds the doctrine of divine providence. If God
does not have knowledge of future contingents, how can he be said to
bestow providence on his creatures? This problem is discussed by
Gersonides both in his commentary on Job and in book 4 of
*Milhamot*. In both texts he argues that providence is general
in nature; it primarily appertains to species and only incidentally to
particulars of the species. God, for example, does not know the
particular individual Levi ben Gerson and does not bestow particular
providence on him. Rather, inasmuch as Levi ben Gerson is a member of
the species humanity and the species philosopher, he is in a position
to receive the providential care accorded to those groups.



For Gersonides, the issues of prophecy, omniscience and providence are
developed against the backdrop of astrological determinism. Like many
thinkers of the late Middle Ages, Gersonides had to confront two
opposing sets of traditions: on the one hand, attacks by religious
authorities (e.g. Augustine's attack in *City of God*;
Maimonides' letters) on the grounds that astrology compromised
human free will; on the other hand, the wide scale acceptance of
astrology from the 12th century on. In the 12th and
13th centuries, most Jewish and Christian philosophers
supported natural astrology, the view that the celestial bodies affect
sublunar life and existence to some extent at least. That the sun and
moon both affect natural cycles and events on earth is unequivocal and
represents a classic paradigm of natural astrology. The calculations
of natural astrology overlapped those of astronomy, and could be
utilized for practical purposes such as fixing the calendar. According
to astrologers, each planet and sign of the zodiac has its own
character, power and attributes. Inasmuch as the characters of the
planets and the signs of the zodiac are opposed to each other, they
are engaged in a perpetual power struggle. Thus the position of the
planets and their interrelation with the signs of the zodiac, regulate
the fate of both individuals and nations. Astrological predictions
could apply, then to both individuals as well as to the history of
Israel and its place in universal history.



An attack upon astrology as a whole belonged to a much larger
conflict, that between the roles of reason and faith. Thus, astrology
should not be situated within the context of magic or the occult, but
rather should be construed as a robust contender to science. Based on
a precise scientific astronomy, astrology was a science accepted from
the second to the seventeenth centuries. On the scientific level it
prevailed almost uncontested until and including Newton.


## 5. Gersonides' Astrological Determinism



Even a summary reading of Gersonides' major philosophical work
evinces an explicit "belief in" astrology. Gersonides
develops his astral determinism in two contexts: in book II of
*Wars* he interweaves astrological motifs into his discussion
of divine providence and prophecy, while in Book V astrology occupies
a central role in the context of his cosmological speculations. His
major concern is the extent to which the stars and planets exerted an
influence over human events in general, or more particularly, over
those actions that entail human choice. Judicial astrology was based
on the assumption that the entire world of nature was governed and
directed by the movement of the heavens and the celestial bodies, and
that man, as an animal naturally generated and living in the world of
nature, was also naturally under their rule.



Langermann emphasizes the teleological nature of astrology for
Gersonides, its chief merit being its ability to provide
"teleological explanations for the wide variety of stellar
motions that are observed to take place" (*Wars*, Vol
III, p. 506). This teleology is reflected in V.2 ch 7-9 where,
after listing 27 problems raised by the heavenly bodies, Gersonides
suggests that only astrological considerations can furnish
satisfactory replies; it is astrology alone that can explain the
connection between the two realms. It is worth noting that on this
point, Gersonides disagrees with Maimonides over the ultimate purpose
of the celestial bodies. For Maimonides it is not possible that a
greater entity, the heavens, would exist for the sake of the sublunar
universe. Gersonides disagrees, maintaining that it is not
inappropriate that the more noble exist for the less noble. The stars,
he argues, exist for the sake of things in the sublunar world
(*Wars*, V.2.3, p. 194). More explicitly, the heavenly bodies
are designed for the benefit of sublunar existence, and they guarantee
the perpetuation of life on earth.



This teleology is spelled out in *Milhamot* II, in which
Gersonides is concerned to explain how divine knowledge operates, and
to what extent divine foreknowledge of future contingents affects
human choice. His major thesis is that divine knowledge is predicated
to a great extent upon knowledge of the heavenly bodies, which bodies
are in turn "systematically directed toward his [man's]
preservation and guidance so that all his activities and thoughts are
ordered by them" (*Wars*, II.2, p. 33). In support of
this teleological cosmology, Gersonides presents an extensive argument
to the effect that the celestial bodies have a purpose. On the basis
of this argument Gersonides concludes that from the perspective of the
teleological structure of the universe, we can understand why the
heavenly bodies behave the way they do. This teleology is reflected by
a "law, order and rightness" in the universe, implying the
existence of an intellect that orders the nature of things: "you
see that the domain of the spheres provides, in the best way possible,
for the sub-lunar world" (*Wars*, V.2.5, p. 137).



As we have seen, the existence of a connection between celestial and
terrestrial events was admitted by most everybody, but not everybody
agreed on the nature of this connection. Gersonides as well must
account for the type of relation obtaining between celestial and
terrestrial events. Having articulated the ordering power of the
astral bodies, Gersonides describes in *Milhamot* V.3 the
separate intellects and the spheres that they move. The main
characteristic of the astral bodies is their luminosity
(*nitzutz*). This luminosity affects their actions and effects
(*Wars*, V.2.3, p. 137). Gersonides is very much aware of the
problem of accounting for how the astral bodies can affect actions at
a distance. The sun, for example, functions as a paradigm for action
at a distance. Once we understand, Gersonides claims, how the activity
of heating reaches earth from the sun, we can understand how the
particular activities of the other stars reach the sublunar realm as
well. By explaining the efficient cause as the light or radiation of
the stars, Gersonides can account for weak or strong effects. As
Langermann has pointed out, Gersonides' account furnishes the
basis for the introduction of astrological causation into natural
philosophy.



In *Milhamot* V.2.8 Gersonides lays out six astrological
principles that affect his general cosmological scheme. These can be
summarized as follows. First, each astral body exercises a different
influence specific to it. Second, astral influence depends upon its
position in the zodiac (*galgal hamazalot*). Third, the longer
a star stays in one place in the zodiac, the greater its effect
because of the strength of its luminosity. Fourth, astral influence is
dependent upon its inclination to the north or to the south; its
effect will be strongest when it is in the middle, as evidenced by the
sun, whose heat is strongest when it is at the Tropic of Cancer as
opposed to being at the Tropic of Capricorn. Fifth, the greater the
radiation or luminosity of a star, the stronger its influence. And
finally, the closer to earth a star is, the stronger will be its
influence (*Wars*, V.2.8, p. 207-8). These principles
function as the underpinnings of his general astronomy as well.



In light of the original problems posed by astrology above, let me
propose that the most important piece of Levi's astrology is
what Langermann calls the variety of the heavens (*ribbui
hayahasim*). Gersonides must be able to account for individual
variety in the sublunar realm. Inasmuch as stellar radiation is the
means by which stellar influences are conveyed, the wide variety of
mixtures of stellar radiation guarantees a sufficient variety of
"influences" on terrestrial processes. The movers emanate
from God who is construed as the "First Separate
Intellect" (*Wars*, V.3.8, p. 272). They are ordered in a
rational system that governs the sublunar domain. If there were no one
first intellect, Gersonides argues, the rational order we see in the
heavens would be the result of chance, which is unacceptable. The
agent intellect thus functions as the link between these celestial
bodies and human affairs. The kinds of information it transmits are of
an astronomical type, as evidenced in the following example: "it
[the agent intellect] knows how many revolutions of the sun, or of the
diurnal sphere, or of any other sphere [have transpired] from the time
at which someone, who falls under a particular pattern, had a
particular level of good or ill fortune..." (*Wars*,
II.6, p. 64). The agent intellect serves as the repository of
information communicated by the heavenly bodies. The patterns revealed
in this communication between agent intellect and diviner (astrologer,
prophet) are from the heavenly bodies which themselves are endowed
with intellects and so "apprehend the pattern that derives from
them." Each mover apprehends the order deriving from the
heavenly body it moves, and not patterns that emanate from other
heavenly bodies. As a result, the imaginative faculty receives the
"pattern inherent in the intellects of the heavenly bodies from
the influence deriving from them." This influence derives from
the position of the heavenly bodies "by the ascendent degree or
the dominant planet [in a particular zodiacal position]"
(*Wars*, II.6, p. 64). However, inasmuch as the heavenly bodies
do not jointly cooperate with one another (*lo yishtatfu*) in
this process, it is possible for the communication to be
misconstrued.



Of course, as we all know, astrologers often err in their predictions.
Astrological errors can be due to several factors. In general,
Gersonides claims, we know very little of the order of the heavenly
bodies. "In general, it is impossible for man to know the
[complete] truth of the order of the sublunar world. This is nicely
illustrated in astrology, where frequently false predictions are made.
All the more so is it impossible for man to know the general order of
the sublunar world by means of its causes so that his knowledge would
be perfect" (*Wars*, I.12, p. 219). In some cases, the
information is not transmitted clearly. Why is it that certain
communications are received more clearly than others? A
constitutionally perfect imaginative faculty receives information from
both dominant and weak heavenly bodies. By 'weak',
Gersonides means that certain celestial bodies are too weak both to
bring about events on earth as well as to transmit information about
these events. Hence he concludes that information about the future
emanates "from the dominant body in the particular proper face
(*panim*) in which it has dominance but not from any of the
attending planets (*ha-meshartim*)" (*Wars*, II.7,
pp. 69-70). But to constitutionally imperfect imaginative
faculties, the information received is only from the dominant heavenly
bodies. Hence the overall quality of the information received will
differ in the two cases. More specifically, because of the difficulty
of obtaining the necessary positions of these bodies by observation,
astrologers are often unable to verify their data. Furthermore, since
the zodiacal position of a heavenly body at any given time is only
repeated once in many thousands of years, astrologers have no access
to the repeatability of those events that would be required to verify
their knowledge. Furthermore, humans simply do not have sufficient
knowledge about the heavenly bodies.



The final cause for error has to do with human free will: as we have
seen above, our intellect and choice "have the power to move us
contrary to that which is determined by the heavenly bodies"
(*Wars*, II.2, p. 34). Although he admits that on occasion
human choice is able to contravene the celestial bodies, nevertheless
this intervention is rare, and true contingency is a rare state of
affairs indeed in Gersonides' ontology. Gersonides presents an
argument to show that human choice guided by reason can subvert the
celestial bodies despite their general ordering of our lives. The
heavenly bodies can order human affairs either by virtue of their
difference of position in the heavens, or from the difference of the
bodies among themselves. Astral bodies, however, will affect different
individuals in different ways; they can also affect an individual
differently at different times; and finally, two or more bodies can
affect a single individual, resulting in multiple influences that can
have contrary effects, echoing the scholastic phrase,
"*sapiens dominabitur astris* [the wise man will be ruled
by the stars]". Gersonides notes that humans can contravene
these effects: God has provided humans with "the intellectual
capacity (*sekhel ba'al takhlit*) that enables us both to
act contrary to what has been ordered by the heavenly bodies and to
correct, as far as possible, the [astrally ordained] misfortunes that
befall us" (*Wars*, II.2, p. 35). Nevertheless, he
assures us that whatever happens by chance is "determined and
ordered according to this type of determinateness and order"
(*Wars*, II.2, p. 34). Outdoing even Plato's hierarchical
structuring in *Republic* IV, Gersonides argues that the
ultimate perfection and ordering of society is due to astrological
influence.



The commensurability of the motion of heavenly bodies raises an
additional concern, having to do with the uniqueness of individual
beings and the doctrine of eternal return. Gersonides' immediate
13th century predecessors Shem-Tov ibn Falaquera and Judah
ben Solomon ha-Cohen discussed this issue against the backdrop of
Aristotle's *Gen. Animalia*. In *Gen. Animalia*,
Aristotle had established a connection between the life spans and
gestations periods of animals and the revolutions of the sun and moon
(*Gen. Anim.*, IV.10, 777b17-778a10). Thus the
revolutions of the sun measure not only time but also produce the
alternating periods of growth and decay. Eschatological predictions
are thus tied to the cyclicity of the heavenly bodies. Gersonides did
not [to our knowledge] indulge in eschatological and millennial
predictions. In fact, Gersonides wrote only one astrological text that
has survived, a prognostication based on the conjunction of Saturn and
Jupiter to take place in March 1345. Gersonides himself died in 1344,
a year before the event in question. As Goldstein has demonstrated,
this conjunction was predicted already by Ibn Ezra, and repeated by
Abraham Bar Hiyya in his *Megillat ha-Megalleh* where the
conjunction was associated with a date of messianic significance that
would supposedly take effect in 1358 (Goldstein 1990, p. 3). The
conjunction was codified by Levi ben Abraham ben Hayyim in his
encyclopedia *Livyat Hen*, indicating an awareness in the
Jewish community of the messianic significance of this conjunction.
According to North, Ibn Ezra was the earliest scholar to record one of
the seven methods for the setting up of the astrological houses;
Gersonides then computed the astrological houses for the
prognostication of 1345 according to Ibn Ezra's method. (See
North 1986, p. 25.) Goldstein suggests that as the date 1345
approached, the Papal court might have become interested as well in
the conjunction. We do know that Gersonides' text was translated
into Latin with the aid of his brother shortly after Gersonides'
death in 1344.



In his prognostication, Gersonides predicts that there will be
"extraordinary evil with many wars, visions and miraculous
signs;" "Diseases and death, and the evil will endure for
a long time;" "the absence of good, pleasure and happiness
for most of the inhabited world;" "the spilling of much
blood and increasing enmity, jealousy, strife, famine, various
diseases, drought and dearth" (Goldstein 1990). The Black
Death, which arrived in Europe in 1347, was thus provided with
numerous astrological credentials. The official statement of the
medical faculty of the University of Paris, presented to the king in
1348, reported on the conjunction of Saturn and Jupiter in the house
of Aquarius on 20 March 1345, which was seen to spread "death
and disaster". It is not hard to see how the conjunction of 1345
came to be associated with the Black Death.


## 6. Ethical Views



Gersonides is not known for his ethical views; as we have seen, most
of his philosophical writings engage matters in the natural sciences.
In his biblical commentaries, however, Gersonides focuses on a number
of ethical issues. To take one example, Gersonides' commentary
on *Songs of Songs* is imbued with an extended discussion of
human felicity. In this work, he claims that because of their inherent
weakness and epistemological imperfections, most human beings are
incapable of achieving felicity: "only very few individuals can
acquire even a large measure of it." (Gersonides, *Songs of
Songs*, 6) For these masses, the Torah and its commandments
function as the best guide to moral perfection. But if immortality is
predicated on intellectual knowledge, and if philosophers such as
Maimonides and Gersonides have argued that many individuals are
psycho-physically incapable of embarking on such a rigorous and
philosophical course of study, does it follow that not all humans can
achieve intellectual perfection: is the road the same, and open, to
all? And is there only one road to ultimate felicity, or are there
many routes?



Horwitz claims that this theme is apparent in Gersonides'
biblical commentaries: "a central role of Ralbag's biblical
commentaries is the desire to help his readers attain eternal
intellectual felicity through knowledge of the truth." (Horwitz 2006,
p. 124) Nowhere is this emphasis seen more clearly than in
Gersonides' commentary to *Song of Songs*. Ostensibly the
*Song of Songs* describes the love affair and desires of a
shepherd for a maiden. Generations of commentators saw in the work an
allegory of the relation between God and the people Israel.
Gersonides, however, provides a philosophical reading of the work that
incorporates two sets of subsidiary dialogues, first between the human
material intellect and the Active Intellect, and second between the
faculties of the soul and the material intellect. Gersonides spells
out the import of these discussions in his introduction to the work.
He first lays down the premise that "man's ultimate felicity
resides in cognizing and knowing God to the extent that is possible
for him." (*Song of Songs*, 5) Such knowledge is achieved
through observation of the state of existing things in the natural
universe, that is, through the beings that God has created and caused.
Knowledge of God, therefore, is predicated on knowledge of the natural
order.



Gersonides then unpacks the various levels of enlightenment that he
finds in *Song of Songs*, moving from mathematics, to physics,
astronomy and finally metaphysics. In this way, Gersonides emphasizes
the natural sciences, in particular physics, as a propadeutic to
metaphysics. Gersonides is clear that the science of physics builds
upon moral knowledge derived from Scripture: "this science is
impossible for one who is not strongly settled on the true views from
the perspective of Torah and speculation." (Gersonides *Song of
Songs*, 11). Gersonides then unpacks the various allegories and
symbolic representations in the work, all of which point to the goal
of ultimate felicity as the union with God via the Active
Intellect.


## 7. Conclusion



Gersonides' philosophical ideas went against the grain of
traditional Jewish thought; he also challenged scholastic thought.
Glasner suggests that unlike his Christian peers who studied and
taught at a university, Gersonides' academic profile as rooted
in applied mathematics and astronomy allowed him to leave metaphysics
behind. He offered a serious critique of Aristotle's theory of
motion, thus freeing himself as well from "the grip of
Aristotelian physics, and even laid down a basis for an alternative
understanding of motion" (Glasner 2015, p. 106). Gersonides
reflects the following characteristics: first, his writings
demonstrate a fundamental interplay and harmony between astrological
and theological beliefs. It is clear that the appeal of astrology lay
in the fact that it offered useful information, while it looked and
operated like a science. Even the critics of astrology had to agree
that the heavens exerted a real influence upon terrestrial events. The
complexity of the rules of astrology and internal disagreement among
its followers served to increase the respect accorded to the science.
Failures did not cause the astrologer to lose faith, just as failures
among modern physicists do not lead to loss of faith in science.
Gersonides believed that life on earth had a meaning, and that
terrestrial events had an order. Astrology was a means of ascertaining
that meaning. Gersonides' views on prophecy, providence,
free-will and evil reflected ingredients of this philosophical
determinism. Whereas his commentaries occupied a central place in
Jewish theology, his philosophical work was rejected. Jewish
philosophers such as Hasdai Crescas and Isaac Abrabanel felt obliged
to subject his works to lengthy criticism. Only in recent years has
Gersonides received his rightful place in the history of philosophy.
As scholars have rediscovered his thought and have made his corpus
available to a modern audience, Gersonides is once again appreciated
as an insightful, ruthlessly consistent philosopher.