## 1. Life and works



Robert Kilwardby was an Englishman born either in Leicestershire or in
Yorkshire, probably, in 1215. He started his university studies in
Paris around 1231, becoming a Master of Arts around 1237. He taught
there until 1245, when he moved back to England, at which time he
entered into the Dominican Order. This marked the beginning of a
rather successful ecclesiastic career. At Oxford (from ca. 1254
onwards), he studied and taught theology until 1261, when he was
elected Prior Provincial of the English Dominicans. In 1269 he
participated in the Dominican General Chapter in Paris where he,
together with Thomas Aquinas (and other members), was responsible for
analyzing the process of Bartholomew of Tours (MOPH I, 155). During
this period he was also involved in a polemic about the nature of
poverty with the Franciscans, after sending a letter on this topic to
the novices of his Dominican Order. Kilwardby's letter is now lost, so
our knowledge of this dispute comes from a response by the Franciscan
John Pecham, who rebuts Kilwardby's claims, while citing extensively
from the Dominican's text. Pecham's hostility towards Kilwardby would
continue later on, when he accuses Kilwardby of stealing
documents--the register and the records of the See and objects
from the See of Canterbury--after Kilwardby's departure from the
See of Canterbury. Kilwardby was nominated Archbishop of Canterbury in
1272. Two of his acts as Archbishop were the coronation of Edward I,
at Westminster Abbey, on the 19th of August 1274 and the issuing of
the Prohibitions of Oxford on the 18th of March 1277 (see Silva
2012).



Kilwardby's participation in this last event is at the same time the
source of his fame and disgrace. The episode itself consisted in the
issuing of a list of 30 denounced articles focusing on the subjects of
grammar (4), logic (10), and natural philosophy (16). Despite
constituting a major episode of academic censorship in the medieval
period, there are two formal points which should not be overlooked:
first, the prohibitory rather than condemnatory nature of the
list--Kilwardby was explicit that these articles were to be
prohibited for being primarily philosophical mistakes and only
secondarily against Christian dogma. Anyone found guilty of defending
and disseminating these mistakes was, if a Master, to be removed from
his teaching position, and if not yet a Master, never to become one
and to be expelled from the university. Second, this list was not the
result of the Archbishop's visit to the University of Oxford and a
subsequent ill-will towards it, but rather it expressed the consensus
of all the regent and non-regent Masters of the University, if the
official documents are to be believed.



The proximity to the the Condemnations of Paris, issued just eleven
days earlier, gave rise to substantial speculation about the relation
between these two episodes of censorship. However, no proof of
connection between them has been presented, nor does it seem that
Kilwardby was acting under Papal orders. The direct targets of these
propositions are still to be identified. Nevertheless, already in
Kilwardby's time, some of the propositions *in naturalibus*
were interpreted as aimed at the teaching of Thomas Aquinas, namely
those propositions related to his doctrine of the unicity of
substantial form. The first reaction came in a letter written by Peter
of Conflans, a disciple of Aquinas, to which Kilwardby replies in a
detailed manner. (Peter's letter has not survived but passages are
quoted by Kilwardby.) Kilwardby's answer constitutes the clearest
expression of his theory of the plurality of substantial forms in
human beings and perhaps the first explicit defense of such a theory.
A more institutional reaction took place when the General Chapter of
the Order, to which both Aquinas and Kilwardby belonged, met in Milan
(1278) and decided to send a commission in order to investigate and
punish those who blackened the writings of Thomas Aquinas scandalizing
the order (*in scandalum ordinis*). The results of this
commission are unknown. The next Chapter, held in Paris, repeated the
recommendation and urged the praise of Thomas' works. Meanwhile, Pope
Nicholas III appointed Kilwardby to the post of Cardinal of Porto and
S. Rufina in 1278, which allowed him to move from England to Italy.
This nomination can be understood either as an attempt to protect
Kilwardby from his own Order or as a way of stopping Kilwardby's
actions against Thomas and Thomism. The Oxford Prohibitions were later
interpreted as a campaign against Thomism (Callus 1955), but this
interpretation has been challenged (Wilshire 1964). A conciliatory
approach could be that in the Prohibitions Kilwardby was criticizing a
presumed interpretation of Aristotle that made Aristotle's doctrine
incompatible with his own reading of Augustine. Kilwardby died in
1279, soon after his arrival at the Papal court in Viterbo, where he
lies buried. (For more bibliographical details, see
Sommer-Seckendorff, 1937; see also Silva 2011; and Silva 2020.)



Two final remarks about Kilwardby's life and thought. First, although
he came to be known as a polemicist, the leitmotif of his work was to
harmonize/reconcile Aristotle and Augustine--a certain
understanding of Aristotle with a certain understanding of Augustine,
that is. Second, his life's work seems to move against the mainstream
of the century he lived in. Most authors had adopted the new
Aristotelian philosophy that new translations of known works and
especially recently discovered ones (to the Latin West, that is) just
made available. Many an author, challenged by these texts, changed
their philosophical alliances from traditional Augustinian thought to
a more modern and progressive Aristotelianism, "spiced up"
by its Arabic commentators. Kilwardby, however, started his career by
being a faithful Aristotelian, as his commentaries (mostly on logic)
on the works of the Greek philosopher testify. It is only after he had
been for some time a Master of Arts at the University of Paris that
his philosophical views changed to become more and more influenced by
Augustine. If one were to define Kilwardby's philosophical
commitments, it would be more correct to say that he was originally an
Aristotelian and converted to Augustinianism without ever ceasing to
be an interpreter of Aristotle. Once we keep in mind that he remained
an Aristotelian throughout his career--of an eclectic type, it
must be said--his thought becomes easier to understand because we
are not drawing him against an anti-Aristotelian background that
doesn't fit the theoretical framework he developed during his academic
career.



A complete list of works by Kilwardby includes texts on logic,
grammar, theology, and natural philosophy. These texts vary greatly in
terms of the influence they exerted on later thought, with the logical
commentaries occupying a place of relevance. Kilwardby's works are
spread over three main periods: the Parisian period between 1237 and
1245; the middle period, around 1245-1250; and the Oxonian
period from 1250 to 1279.



In the Parisian period Kilwardby wrote mainly logical commentaries,
among which should be counted those included in the *Course on the
Logica Vetus* (Lewry 1978): on the *Isagoge*,
*Praedicamenta*, *Perihermeneias*, *Liber Sex
Principiorum*, and *Liber divisionum Boethii*. The edition
of the whole course was started by the late Patrick Osmund Lewry and
is currently being completed by Alessandro Conti (University of
L'Aquila,
 Italy).[1]
 The commentary on the *Isagoge* has been the object of a
comparative study by David Piche (2002), and the commentary on
the *Categories* is available on-line in a provisory edition by
Alessandro Conti. Kilwardby also wrote commentaries on Aristotle's
*Prior* and *Posterior Analytics* (the former published
under the name of Giles of Rome), as well as the commentaries *In
librum topycorum* (partialy edited by Weijers, 1995; the
attribution of this work still remains uncertain), *De Sophistici
Elenchi*, *In Priscianus Minor*, and *Notulae libri
Prisciani De accentibus* (ed. Lewry, 1988). The commentary on the
*Prior Analytics* was recently edited and translated by Paul
Thom and John Scott--having received careful examination in Thom
2007--and the *Commentary on the Posterior Analytics* has
received a provisory critical edition in an unpublished PhD
dissertation by Debora Cannone (2003-2004) and more recently
examined in Thom 2019. The commentary on the *Priscianus Minor*
remains unedited, but has been examined by Irene Rosier (1994),
who transcribes the most relevant passages. Kilwardby is also the
author of a *Commentary on the Old and New Ethics*; the edition
of this commentary, which was started by Lewry and continued by
Anthony Celano (Stonehill College), is now
 forthcoming.[2]



From the same period, and previously thought to be Kilwardby's but now
generally regarded as unauthentic, are the *In* *Priscianus
Maior* and the *Sophismata grammaticalia*. Also the
authorship of *In Donati artem maiorem III* (ed.
Schmucker, 1984) and *Sophismata logicalia* is now highly
 disputable.[3]
 The commentaries on the *Physics* and on the
*Metaphysics* that were identified by Gal (1953) are now
securely attributed to Geoffrey of Aspall (Macrae 1968).



In the period around 1245-1250, when he was moving from Paris to
Oxford, Kilwardby wrote the encyclopaedic treatise *De ortu
scientiarum* (ed. Judy, 1976), a treatise on the nature of time
(*De tempore*), and a work on perception entitled *De
spiritu fantastico* (both works were edited by Lewry, 1987).



During the Oxford period (after 1250) Kilwardby wrote an array of
disparate works: *De natura relationis*, *Quaestiones in
quattuor libros Sententiarum*, *De 43 questionibus*, and
*Epistola ad Petrum de Confleto*. All these works have been
edited, even if not all in a critical edition. From the same period
are also some minor theological works such as *De confessione*,
*De necessitate Incarnationis*, *De conscientia et de
synderesi*, the *Tabulae super originalia patrum*, the
*Arbor consanguinitatis et affinitatis*, and some
sermons--the *Sermo in capite ieiunii* and the *Sermo
in dominica in Passione*. The two sermons have been edited, as
well as the work on the necessity of the Incarnation. Worth mentioning
is a letter expressing some criticism over Franciscan poverty
(*Epistola ad novitios de excellentia Ordine Praedicatorum*),
which survives in John Pecham's answer (*Tractatus contra fratrem
Robertum Kilwardby*), edited in Pecham's *Tractatus tres de
paupertate*.



Early lists of works, such as the *Stams Catalogue*, attribute
to Kilwardby the *De unitate formarum*, *De physica*,
and *De metaphysica*, whereas Nicholas Trivet mentions the
treatise *De universali*. This latter work is possibly a
reference to a passage in Kilwardby's *Notule Libri
Posteriorum*--"Hec est pars in qua Aristotiles
determinat de uniuersali" (Cannone 2002, 132)--which might
have circulated isolated from the rest of the work. In the same way,
the work *De unitate formarum* clearly is the last (7th)
article of Kilwardby's answer to a letter sent to him by Peter of
Conflans, and it is found alone in some manuscripts.



Recent years have exhibited an increased interest in Kilwardby's
thought and this has been accompanied by substantial editorial work,
even if much remains to be done. The texts from the middle and later
periods are almost all edited. With the edition of his commentaries on
the *Prior* and *Posterior Analytics*, as well as on the
*Ethics*, only the commentaries of the old logic and the
grammatical works remain unpublished. Recent work by
Mora-Marquez, Thom, Hansen, Conti, Silva and Thornqvist to
name just a few (see Bibliography), has focused on logical aspects of
Kilwardby's thought in relation to some of his philosophical
interlocutors, such as John Pagus, Nicholas of Paris, and Albert the
Great. In this article I will focus on a cursory presentation of
Kilwardby's main philosophical doctrines. A fuller account of these,
with exception to 5.2.4, 6, and 7, can be found in Silva 2007, 2008,
2009, 2010, 2011, 2012, 2013, and 2020.


## 2. The Theory of the soul and the plurality of substantial forms



A human being is a composite of two substances, the body and the soul
(DOS 316). The soul is the act and form of the whole (*totius*)
human body (NLPor 8, P 38vb), and it is present wholly in every part
of the body (*in qualibet parte corporis tota*). To be present
wholly in every part does not require simplicity, as absence of
composition, but spirituality (that is, immateriality) (E 6,
47-48).



According to Kilwardby, the human soul is a composite of three forms
(*potentiae*): vegetative, sensitive, and intellective. The
vegetative and sensitive are qualified as the principles of life
because through them the being performs the operations of life. Like
most of his contemporaries, Kilwardby claims a double origin for the
parts of the human soul: the vegetative and sensitive result from
natural generation, that is, they are educed from the active
potentiality of matter, whereas the intellective soul is created
directly by God. It is created as the perfection of the human body and
as a *hoc aliquid* (E 5; QLIIS 138, 370), that is, an
individual in the genus of substance. The intellective soul is a
spiritual substance of the rational kind, but is not a person because
it is part of another thing--a human being (QLIII1S 8, 36). The
soul constitutes a person only when united with the body in an actual
existing human being (QLIII1S 10, 52). A human being is constituted by
the rational soul and the body (E 7, 51).



This difference in genesis explains the different nature of the
intellective form with respect to the other forms: whereas the
vegetative and the sensitive forms are defined as acts of the body,
the intellective form is the actuality of no part of the body and so
is the act of the sensitive body in the sense of being its perfection:
it is the completion of the process of development, by making it a
full member of the human species. The relation of the intellective
form to the body is that of the sailor to the ship (*sicut nauta
navi*), but this union is accidental only from the point of view
of its operations--such as in understanding, where the
intellective soul does not need bodily organs (DOS 56)--but not
from the point of view of the essence of the intellective soul (DOS
53).



An essential feature of the intellective soul is its natural desire
and inclination (*appetitus et inclinatio naturalis*) to be
united to a body capable of sensation (as it "hates" being
separated from it; DOS 358). The intellective soul can exist without
the body, but it is not created to exist without it, as it has, on the
contrary, a natural inclination to be united with it. It is this
'unibility' that differentiates it from the angelic
intellective soul (in the same way as the human body is differentiated
from the bodies of other animals; QLIIS 7, 26). In Kilwardby's own
words, "the [human] soul is born to move and to perfect the
body, and in this way it differs from an angel" (see also QLIIS
6; in this he follows Bonaventure). The intellective soul is the
specific (completive) difference in both, but it differs in species:
whereas the human intellective soul is created to be united with a
body, the angelic intellective soul is non-united with a body (QLIIS
6, 23-24; 7, 26). This unibility (*unibilitas*) or
aptitude to be united with the body is not an accidental feature but
something essential to the human intellective soul (QLIIS 7, 27).



The utmost justification for this unibility is the intellective soul's
natural capacity to know everything--an application of the
Aristotelian principle that human beings desire to know everything.
The rational soul is born (*nata est*) to know things in a
twofold manner. The intellect can turn itself to the eternal, superior
reasons, but can also turn its attention both to the images of
sensible things received through the senses and abstracted from the
phantasms (DSF 25; QLIII2S 24, 84). In so far as knowledge of material
things depends on the use of the senses, the intellective soul can
only fulfill its perfection by means of its union with the body (QLIIS
8, 32).



Once infused by God, the intellective form connects the previous forms
inherent in the body of the embryo (vegetative and sensitive) and
constitutes with them a human rational soul, "in much the same
way as a quadrangle, which in fact contains two triangles would become
a pentagon, if a triangle were added to one of its sides" (D43Q
34, 37; see also E 5, 42). The addition of the new triangle to the
existing quadrangle--composite of two triangles--does not
cause the corruption of the existing figures, but rather complements
and completes them. In the case of the soul, it means that the
vegetative and sensitive *potentiae* continue to be responsible
for their operations after the infusion of the completive intellective
*potentia*. The result is the thesis of a pluarlity of forms in
the human soul.



Kilwardby's theory of the soul is formulated around the central
conceptions of unity and composition, rather than those of unicity and
simplicity. According to Kilwardby, "all composite things have
unity, even though they do not have simplicity" (E 6, 47),
meaning that complexity is not incompatible with unity, only with
simplicity. What is required in addition is only a principle strong
enough to justify the unity. He thinks to have found it in what we
could call 'the principle of ordination': a substance can be composite
and nevertheless one when the essentially different parts are ordered
to each other (*ad invicem*), from the less to the more
complete. A human being has "one form which is not simple
(*simplex*) but a composite of many [*potentiae*] having
a natural order to each other" (E 7,
 53).[4] These forms are organized in a hierarchical structure so that
there is one which is the perfection of the whole composite. In the
case of human beings, that last completive form is the intellective
soul.



Before continuing the examination of Kilwardby's theory of the human
soul, some terminological remarks are in order: Kilwardby uses the
term *potentiae* mostly to refer to the vegetative, sensitive,
and intellective souls. There are some exceptions, where he uses
*formae* and even *formae substantiales*, but the rule
is *potentiae*. For the most part, I leave the term
'potentia' un-translated because the options are
problematic: 'power' should be used to translate
'virtus' in the sense of 'faculty' (for
example, memory is a power of the soul); 'potency' should
be avoided in order not to confuse it with potentiality, as in active
potency; 'soul' is misleading because most (if not all)
pluralists claimed that there is only one soul in any individual human
being--the disagreement between them and unitarians is about
whether there is one or many *potentiae* in a individual human
soul rather than whether there is one or many souls in a individual
human being; 'form' is a too general term--however,
for the sake of simplicity I sometimes shall use it, namely in the
context of the debate over unicity versus the plurality of substantial
forms as that is the traditional designation of the debate. I
thoroughly use the term 'unicity' to refer to the view
according to which the soul is simple, being only one form. Unity is
often used in scholarship, but I find it problematic because
pluralists--such as Kilwardby--also argue for the unity of
the soul, as said above, only disagreeing about its simple (versus
composite) nature. Finally, I use 'intellective' soul/form
(*potentia intellectiva*) to refer to the specifically human
part of the soul; the rational soul (*anima rationalis*) refers
to the whole human soul--which includes the vegetative and
sensitive forms. Kilwardby adopts this distinction for the most part,
but there are passages--especially in E 5 and QLIIS 8--where
he uses rational (*rationalis*) and intellective
(*intellectiva*) interchangeably.



One of the most important passages in which Kilwardby carefully
discusses the human soul is E 5. Here he presents what he takes to be
the three more important theories of the human soul, its substantial
nature, and its *potentiae*. I focus on the first of these
theories, which is the one he most vehemently criticizes, and on the
third, which is his own. They can be displayed in the following
way:



(1) According to the first theory, the human rational soul is a
substance that is simple in its essence, in other words it has no
parts. It is the same essence that vegetates, senses, and understands.
The problem Kilwardby identifies in this theory is that the
vegetative, sensitive and intellective *potentiae* are found in
different kinds of beings: the vegetative is found without the others
in plants, the sensitive without the intellective in non-rational
animals, and the intellective without the other two in spiritual
beings. But, if that is the case, how do they come to be one and a
same simple essence in humans? The only way to sustain such a thesis
would be to argue that these *potentiae* are equivocally said
of humans and other beings; but that is manifestly false: if the
objects and operations of the powers are the same, the powers and the
*potentiae* in which they are rooted must also be the same. For
example, in both humans and other living things the operations of the
vegetative part of the soul are to take nourishment, generate, and
grow. Therefore, the vegetative *potentiae* is the same in all
living things and the sensitive is the same in all animals (E 5,
35-6). The problem is that if all three parts of the soul
constitute one and the same simple essence, then



(I)
plants would be endowed with an intellective part of the
 soul.[5]


If that were the case, they would have intellective souls without
having appropriated bodies; so



(P)
a perfection exists without that which it is supposed to perfect
by existing.


That is, for Kilwardby, manifestly false. A further problem with this
simplicity of the essence concerns the coming into being of the soul.
If the three *potentiae*--vegetative, sensitive, and
intellective--constitute a simple essence, then they must come
into being either



(*x*)
all in the same way, that is, (*x*') by creation or
(*x*'') generation; or
(*y*)
each in different ways, that is, by creation in human beings and
by generation in plants and animals.


Kilwardby simply rejects (*y*) because it asserts the existence
of a naturally generated intellective soul in plants and animals.



> 
> 
> If (*x*'), then the souls of plants and animals are
> created out of nothing, which means they cannot be corrupted.
> 
> 
> 
> If (*x*''), then the human soul is *ex traduce*
> (hereditary), whence corruptible.
> 
> 
> 



Both lead to absurd consequences and must therefore be dismissed.
Instead, Kilwardby argues for the double origin of the
*potentiae* of the soul, which implies that they must be
essentially distinct.



(2) According to this theory, the human soul is constituted by three
substantial forms (*tribus formis substancialibus*) which
differ essentially from one another; of these, two (vegetative and
sensitive) are the result of the work of nature (*opus
nature*)--by means of the potencies of elements and the
original principles with which the matter of transmutable things is
naturally endowed--and the intellective form is the result of
divine creation. The three forms are present at the same time in the
human embryo only after the intellective soul has been created and
infused into the developing being, not before--and this is due to
the need for an appropriate level of material organization that
disposes the being to receive the intellective soul as its perfection
(E 5, 44).



These forms make together one human soul, which is the form of the
human body. Each of these forms can be considered either in respect to
the body they vivify and in this sense (as essential determinations)
none of them is the form of the others, or as constituting part of a
soul that is the animating principle of a certain kind of life, the
human life, and in this sense the intellective part is the form that
complements the others (QLIII2S 63, 268). In the actual constitution
of all natural things that comprise one natural whole, there are
several dispositions that prepare for and are perfected by the last
form, which completes the thing (QLIII2S 63, 269). In the case of
human beings, the intellective form is the 'completion of human
life' (D43Q 34), that is, that which makes that particular life
to be a specifically human life. This is the theory Kilwardby takes to
be in agreement with philosophical reason and Christian faith and the
one to which he adheres.



Kilwardby is clear in showing that his criticism is aimed at the
conception of the soul as a simple form, as he clearly advocates a
view of the human being as composite of a plurality of essentially
different forms. This view is not incompatible with their making one
soul, which is the form of a living thing. In the same way as the body
is a unity even though it is constituted by a plurality of
parts--foot, hand, blood, bone--each having its own
form--the human soul also is constituted by a plurality of parts
and nevertheless is a unity. The parts of the body make one body by
aggregation.



The human (rational) soul is, according to both Aristotle and
Augustine (as Kilwardby claims), a substance composed of three
essentially different parts--the vegetative, sensitive, and
intellective--just as a definition having three differentiae is
composed (E 5, 43). The unity of the soul is grounded in a hierarchy
of forms, where some are incomplete and dispositional, while one is
completive and perfective.



Each of these three forms has powers through which it performs the
operations that are proper to it. Powers are defined by their actions,
which in turn are defined by their objects. The powers of the
soul--for example, memory or intellect--are active
potentialities; once activated by an external agent they bring about
their own actualities by way of their operations--for example,
understanding in the case of the intellect. This conception of powers
means that a human being performs different kinds of operations via
different forms: a human being understands by means of a power
belonging to the intellective form, not to the sensitive or vegetative
forms (E 5, 43). Essentially different operations are rooted in powers
belonging to essentially different forms; for example, perceiving
requires bodily organs and understanding does not (QLIIS 8, 29; E 7,
51). As the result, human beings must be composite of essentially
different forms.



Despite being composite in substance and powers, the soul is simple in
existence in that it is not divisible and exists wholly in every part
of the body (*tota in qualibet parte corporis*) (E 6,
46-48). There is, however, one type of unity mentioned in the
beginning of this entry that needs to be addressed: the unity of being
or substantial unity, the unity formed by the body and the soul, which
is properly a human being.



Kilwardby subscribes to the principle according to which two actual
things cannot make one thing in actuality. But this principle, he
claims, does not apply to the body and soul because neither the
intellective soul nor the sensitive body--that is, the body
informed by the sensitive form--are one complete being. The
sensitive body is not perfect and needs to be completed by the
intellective form, and the intellective form is created to be the
perfection of the sensitive body (E 5, 41).



Kilwardby has such a desire to substantiate this unity that he finds
himself in an extremely difficult position when considering what
happens to the soul and the whole of its *potentiae* at the
death of the body. He sees no particular problem in arguing for the
immortality of the intellective part of the soul, but he hesitates in
what happens to the vegetative and sensitive forms in such a way that
he ends up giving two opposite accounts, one aligned with Aristotle,
the other with Augustine. On the one hand, according to the former,
the vegetative and sensitive forms, operating only through the body,
cannot remain after death; as they were naturally generated, they were
created by God to be re-united with the resurrected body and the
immortal intellective soul at the end of time. On the other hand,
according to Augustine, the bond which unites all the
*potentiae* of the soul is so strong that it cannot be broken
with the separation from the body; the whole soul remains in the
disembodied state, and the soul is able in this state to perform acts
of imagination--not by receiving images of sense objects from
sense experience but from the power of memory. He indicates no clear
preference for either account although the Augustinian would seem more
in tune with his general theory of the soul.



Finally, it is obvious from his account in E 5 that Kilwardby is
opposing contemporary theories of the soul of the time. In his letter
to Kilwardby, soon after the Prohibitions, Peter of Conflans inquires
about whether he is critical of the theory of the unity of forms
(*positio de unitate formarum*) associated with the name of
Thomas Aquinas. In the only place Kilwardby explicitly addresses the
so-called theory of the unity of forms he describes it as holding that
there is only one form that when it supervenes the existing composite
corrupts all the existing forms and it performs by itself all the
actions.



First, according to Kilwardby, such a theory claims that there is one
last form which is the perfection of the composite; second, that all
the other forms informing matter would be corrupted by this perfective
form, hence, only one form would remain in the whole composite; third,
that one and the same form is responsible for all the operations the
being performs. Kilwardby argues against this theory--which
resembles but is not to be identified with any of the theories
presented in E 5--with an array of objections, of which the most
relevant are:


1. to have a perfection corrupting rather than perfecting that which
it is supposed to perfect makes not only useless the work of nature in
producing those forms, but it also leaves unaccounted for how the
parts of the body remain the same if everything is corrupted down to
prime
 matter[6];
2. if the human composite is constituted only by prime matter
(*materia nuda*) and the last form (intellective), then how can
we account for transubstantiation, incarnation, and resurrection?
3. if the same (intellective) form performs all the operations, it
means that the intellective soul operates both through bodily organs
(as in digesting and perceiving) and without bodily organs (as in
understanding). Moreover, this constitutes, according to Kilwardby, a
violation of the Aristotelian principle according to which the
diversity of objects implies a diversity of powers which implies a
diversity of forms.



Kilwardby concludes that such a position is incomprehensible and leads
to major philosophical and theological difficulties; it should
therefore be avoided.



## 3. Matter and seminal reasons



In a clear adoption of what is called universal hylemorphism,
Kilwardby claims that everything that subsists on its own, apart from
God, has two compositing principles, a *quod est* (matter) and
a *quo est* (form) (DOS 256; 265; 268; QLIS 35, 90; QLIS 60,
171; QLIIS 14, 51-2).



Three main issues arise from Kilwardby's treatment of matter:



> 
> 
> (i)
> the unity of matter,
> (ii)
> the three kinds of matter, and
> (iii)
> matter in spiritual substances.
> 
> 



In (i) the discussion about the unity of matter arises from the
questions of whether spiritual beings have matter and whether this
matter is in some way common to the matter of corporeal beings
(univocally, i.e., whether it is matter in the same sense) (QLIIS
14-16; DOS, chapters 29-31). According to its editor,
Albert Judy, DOS 31 is probably the result of a public disputation on
the topic by Kilwardby or one that he attended and is here reporting.
What is clear in any case is the relation between the views presented
in this chapter and those of some of Kilwardby's contemporaries, such
as Roger Bacon, Albert the Great, and Bonaventure (see also Donati
2013). The nature of matter is of particular significance due to the
role it played in the Prohibitions, with a number of articles being
about the nature of privation, prime matter, body, and active
potencies in matter (Silva 2020, chapter 2).



Kilwardby starts by distinguishing two ways of considering prime
matter (*materia omnino prima*):



> 
> 
> (#)
> According to its being (*secundum esse*), that is,
> considered in its existence together (*concreta*) with form,
> matter is considered with respect to actual existing beings
> (*actualiter exsistentibus*). In this case matter is one or
> many according to the form(s) it receives: a plurality of individuals
> is the result of a plurality of forms informing matter (because form
> is the form of a concrete individual thing). As such there is not one
> matter in all things, but one or many according to the number of
> individuals. In the same way as there are no two individuals that are
> one and the same, matter cannot be one in all things. It can, however,
> be one within all (*in omnibus*) the individuals and species as
> one genus, that is, insofar as it is conjoined (*concreta*)
> with the most general form (*forma generalissima*), in the
> category of substance (DOS 277). In this sense, matter is one and the
> same in all things, corporeal and spiritual alike. Kilwardby
> explicitly identifies this view as being that of Averroes.
> (##)
> According to its essence (*secundum essentiam*), that is,
> considered *in se* and *per se*, abstracted from any
> form (DOS 272), there are two possible views:
> according to the first, matter has an essential unity (*unitas
> essentiae*), being potential with respect to any form whatsoever.
> Form is the principle of distinction and diversity; thus, prime matter
> considered on its own, prior to the reception of any form, is simple
> and one because it lacks the distinction that arises from being united
> with form. The problem with this view, for Kilwardby, is that the
> reception of the specific forms requires the existence in matter of a
> certain formal disposition (which begs the question). One and the same
> matter cannot be indifferently receptive of both corporeal and
> spiritual forms.
> According to the second view, there is a diversity of essence:
> matter is not one and the same in all things but diverse in different
> things. This diversity of essence remains even when all the forms that
> constitute any individual of one the kinds of being--spiritual,
> corporeal, and natural--are (in thought) removed. According to
> this theory, the essence of the prime matter, which constitutes any
> individual, has different grades of purity. Prime matter has
> substantially different parts, sharing an essence that is one by
> analogy.
> 
> 



Whereas in DOS Kilwardby remains neutral to any of these views, in
QLIIS 15 he seems to align himself with the view that the essential
unity of matter is analogical, not numerically one. In E 2, however,
Kilwardby approaches the question in slightly different terms, which
can be explained by the fact that his motivation is different: whereas
in DOS and QLIIS he intends to justify the distinction between
corporeal and spiritual things, in E he wants to understand matter as
that which underlies change. From that point of view, there are three
kinds of prime matter:



> 
> 
> (APM)
> absolute, pure, or naked prime matter (see also DNR 23,
> 51-52),
> (BPM)
> bodily prime matter, and
> (PPM)
> natural or physical prime matter.
> 
> 



APM has no form whatsoever and underlies (*substat*) all forms
it receives: first the general forms, then the special forms. Even
then, Kilwardby claims, matter is not nothing *simpliciter*,
that is, lacking being but rather nothing actual (*sed non ideo
dicitur simpliciter nihil, sed nihil actuale*: QLIS 79, 254).
Naked prime matter receives first the form of the most general genus,
substance, and through this form prime matter is divided into
numerically distinct things (only form distinguishes; QLIIS 16, 60;
DOS 208; 406). This is the matter common to spiritual and corporeal
things.



Then, substance receives the form of corporeity, by means of which it
becomes a body with dimensions and magnitude (DOS 246)--that is,
matter gets extended and occupies space (DOS 340; NSLP 8, 55). This
matter is BPM and is common to both celestial and terrestrial bodies.
Regarding BPM, it is necessary that there be one matter that is the
substrate of substantial change in the case of terrestrial bodies; or
circular motion in the case of celestial bodies. This matter is the
corporeal substance, that is, substance plus the form of corporeity
(DOS 244-245). When something looses a substantial form, it is
not annihilated but remains at least with dimensions and the form of
corporeity (E 1, 21), as when a dead body is reduced to its state of
being a mere aggregate of its components indicating its composition
(*cimbolum sue mixcionis*) (E 5, 40; DOS 244). Finally, matter
receives the specific differences of bodies and the passive and active
qualities (DOS 248). This is PPM, the matter common to all simple and
mixed bodies in the sublunary sphere, that is, those that are
generable and corruptible.



Matter and form are the constitutive principles of a thing, but there
are three principles of change: matter, form, and privation. According
to Kilwardby, privation 'is not pure nothing' or even pure
absence of form but the state of 'actively' lacking that
something imperfect has with respect to fulfillment (E 3,
31)--and only in this way can privation be understood as a
principle of change. Privation is the state of a potentiality that
does not have the perfection that is owed to it (E 3, 30). In that
sense, privation is associated with active
 potency.[7]



Kilwardby argues that PPM is naturally endowed/pregnant
(*gravida*) with active potencies that, once set in motion by
the action of an external agent, co-operate in change and become fully
 actual.[8]
 An active potency "is called potency because it is ordained to
actuality and active because it is something of a form" (E 3,
30). Matter strives for form and the action of striving entails the
existence already of something of form, which is the active potency.
Potentiality is therefore taken not as mere receptivity of form but as
an active appetite for (full) actuality. An active potency is a form
in an incomplete state because it was born to make itself actual
(*nata est facere se in
 actu*).[9]



The existence of matter endowed with forms in an inchoate state is
necessary, according to Kilwardby, in order to distinguish generation
from creation as well as to assure that generation is a natural (and
not violent) change--since an active potency is an internal
principle of motion. Another of the applications of the notion of
active potency is to explain elemental change. Every part of PPM that
is informed by the form of a body has the forms of all four elements
in potency. At any given time, only one of these forms can be actual.
The elements transmute into one another in virtue of their active and
passive qualities (DOS 249). With this account, Kilwardby addresses
the question of the presence of the four elements' forms existing
within mixed bodies differently from other authors of his time. He
takes his notion of potency, being a form in an inchoate state of
actuality, as sufficient to avoid the problem of the simultaneous,
fully actual presence of contraries in one and the same subject.



The third application of the notion of active potency is to explain
human generation. Kilwardby appeals to a (then) well-known concept,
especially in the Augustinian milieu, of seminal reasons (see Karger
2002; Donati 2002). Seminal reasons are a philosophical concept used
by Augustine in order to explain the theological problem of two
apparently incompatible accounts of creation: one according to which
everything was created in an instant, the other that there were
successive moments of creation (described in the six days narrative of
the *Genesis*). Kilwardby interprets this concept as meaning
that everything was *created* immediately but not everything
was *made* immediately (QLIIS 61, 174): in Creation, God
created corporeal matter out of which He produced the first light as
well as the first individuals of the different species (D43Q 1, 11;
QLIIS 85, 240). When He created the first individuals, He inserted in
them these seminal reasons (QLIIS 63, 179; D43Q 15, 21; 26, 29; QLIIS
61, 176), which are the cause, through the generative power, of the
continuous generation of individuals, therefore explaining the
propagation of species throughout time without the need of divine
intervention (E 4, 32; E 1, 22; 5, 39-40; D43Q 26, 31).



In the process of the generation of a human being, the father
transmits to the descendent matter--endowed with seminal reasons,
which contribute to the preservation and continuity of the
species--and the corporeal spirit. These are present in the
semen, as the first principle of life and the power of the principle
of life. The principle of life is that which first receives the action
of the soul, the one in which the soul is realized; the power of the
principle of life is that which acting as an efficient cause brings
the active potency in matter to actuality. In the same way as a plant
germinates from a seed, the vegetative and sensitive souls (the
principle of life) exist in an inchoate state in the semen separated
from the father, and they are educed from this matter by the action of
the corporeal spirit (the power of the principle of life--D43Q
34, 37; QLIIS 85, 239).



Making use of the medical and philosophical knowledge available to
him, Kilwardby argues that the semen cannot be just a superfluity of
digested food because in that case the offspring would resemble the
father's aliment and not the father (E 4, 30). In addition to the role
played by the father in the generation of the new being, the mother
contributes to the offspring with matter that is used to protect and
feed the embryo (some matter of the semen has the same purpose) and
the local warmth that constitutes the proper environment to the
development of the new life.



Before concluding this section on matter, it is worth returning to
point (iii) above, where it was clained that matter is a metaphysical
constituent of things and is necessary for explaining change,
receptivity of accidents, and individuation. Therefore, all created
things must have matter and form in their constitution, as befits the
position of universal hylemorphism. But, whereas things that are
subjected to generation and corruption are made out of natural or
physical matter (*materia physica*)--matter in the proper
sense (*proprie*)--spiritual things also have matter, but
in the common sense (*communiter*) of metaphysical matter
(*materia metaphysica*). This matter is the subject of the
spiritual form (DOS 265; QLIIS 82) and is defined as potential being
(QLIIS 14). Matter in this sense explains individuation (DOS
266-269) as well as change (other than substantial change) that
takes place in spiritual substances (DOS 320). (For Kilwardby's view
in the context of Thirteenth Century debates on matter, see Donati
2013)


## 4. Individuation



Among the issues Kilwardby has changed his mind about during his
career is the principle of individuation: whearas in his Parisian
period he assigns to matter the role of the cause of individuation
(NSLP 7, 39), in the mature works of his Oxford and Canterbury stay,
he claims that the principle of individuation is matter *and*
form.



A main tenet in Kilwardby's ontology is that every thing that exists
outside the soul either exists in an individual or is itself an
individual (QLIIS 17, 64). As all substances are composites of matter
and form, matter and form are the two possible causes of
individuation. It cannot be matter on its own because matter receives
its determinations from form. It could be form, but in this case it
would be either accidental or substantial form. He promptly dismisses
the first possibility, since accidents can only inhere in an already
constituted primary substance, that is, they follow the constitution
of an individual substance rather than explain the constitution of
that substance as an individual. This is not to say, he points out,
that there are individuals without accidents: a sublunary,
corporeal individual is always temporally and spatially located,
even though one can think of an individual without reference to this
particular place and time (QLIIS 17, 68).



His final answer is that both matter and form are principles of
individuation: matter as the passive cause (*causa receptiva*;
he also calls it the *causa sine qua non*), form as the active
cause (QLIIS 17, 64). Individuation is achieved when the last species
(the *species specialissima*) completes the individual (QLIIS
17, 67). Form, arriving at matter, designates matter and designating
matter, designates itself. The designative action (*signatio*)
of form on matter is the cause of an actual existing being (QLIS
71).



The distinctive property of the individual as such is precisely this
actual existence (*actualis exsistentia*: QLIIS 17, 65; QLIII1S
9, 39). Kilwardby rejects the view that individuals have an essence in
addition to the form of the species: there are no individual forms,
only individuated forms. Otherwise, he argues, the essence of the
individual would be distinct from the essence of the universal, and
each individual would be made of two essences (Lewry 1978, 246). The
individual has only matter in addition to the
 species.[10]
 What Kilwardby means is that the individuated form of the species is
accidental to the species because a particular instantiation is
irrelevant to the species--even if it is essential to the
individual as such--as there would be no individual without a
form of the species (QLIIS 17, 65). This idea is the basis of
Kilwardby's moderate realism of universals and his doctrine of the
plurality of substantial forms: universal forms--genera and
species--exist in individual things as their constituents, but as
such (that is, as forms existing in individual things) they are not
universal forms but individuated and individuating forms. As universal
forms, they exist in the intellect only, by abstraction from the
individuals that instantiate them. There is in the world outside the
mind no universal human being aside from individual human beings.


## 5. Theory of Knowledge


### 5.1. Active sense perception



Kilwardby's lengthiest discussion on sense perception is found in the
work *De spiritu fantastico*. Here, Kilwardby argues that for
an act of perception to occur, certain requirements need to be met:
there needs to be an object, a sense organ, and a medium between them;
the object must issue/generate a likeness (image or species) of itself
by means of which it can be known (since nothing in the world can be
known except by generating a species of itself). The likeness must be
able to change the medium and then the sense organ. Both the medium
and the sense organ, in different ways, must be appropriate to the
likeness, that is, must be receptive of it. In the case of sight, for
instance, the medium must be transparent, and there must be light (E
5, 42).



The change in medium is different from that in the sense organ, and
different species seem to move (in) the medium in different ways.
Kilwardby connects this with the materiality and even the different
degrees of materiality of the species: the species of smell and
hearing move with the airwaves, whereas the species of color do
 not.[11]
 With respect to sight--the prototypical sense discussed in
medieval theories of perception--the object, according to the
rules of optics, must stand opposite the perceiver's eyes, and the
species move along a straight line. There are two objects of sight:
light and color; but whereas color (and by means of it the colored
thing) is that which is perceived, light is that which makes this
perception possible (QLIII2S 5, 18). Light is not perceived as such;
only the mind (not the sensory soul) is able to distinguish light from
color, by reflection (QLIII2S 26, 190).



In DSF 103, Kilwardby provides a careful synthesis of the process of
perception, which can be described in terms of the two
motions--outwards and inwards:



> 
> 
> For there are two things in sensing, namely, the more attentive action
> of the soul in the body which is acted upon, and the perception of
> this action. (trans. Broadie)
> 
> 
> 



The acted-upon refers to the affection (*passio*) of the sense
organs by the sensible object, more precisely, the impressing of the
likeness of the object (the sensible species) in the sense organ. This
affection is a certain kind of alteration through which a disposition
is perfected--in other words, the potentiality of the sense organ
to receive a certain quality is actualized (DSF 61-62).



The attentive action is the *sensory* soul's assimilating
itself to the species received in the sense organ, and by means of
this assimilation makes in and from itself (DSF 126) an image or
likeness of the sensible species (DSF 166; 121; 185). It is by means
of this assimilative action that the image of the sensible object
comes into being in the sensory soul. The sensory soul (not the
intellective, DSF 140) forms the image as if by natural instinct
(*instinctu naturali*), that is, it has a natural capacity to
do it (DSF 128).



Finally, the perception of the soul's action is "to sense in
itself the image which it has formed in itself" (or, "the
turning of the eye <of the *soul*> upon itself, in and by
means of which the image is sensed" (DSF 125), that is, the
perception of the object. In other words, the sensory soul turns its
eye upon itself and sees the sensible object through the image made by
itself. It does not distinguish the image in the sense organ from the
image in itself (DSF 104), and neither image is that which is
perceived. The object of perception is the external thing (DSF
110-11) and not the image by which the thing is known (*quo
res cognoscitur*) (QLIS 89, 280).



According to Kilwardby, the soul is the active element in the process
in that perception is possible due to the soul's intentional state
with respect to the affection of the organ. The reason the soul
permanently attends to the body and its affections is that it is
proper for the soul, as the form of the body, to take care of the
well-being and preservation of the body (DSF 100-101; Silva
2008). The soul avoids all affections that can injure and damage the
body and its organs, which are the soul's instruments for acquiring
information about the external world. The soul's control over the body
is exercised through the mediation of the corporeal sensitive spirit,
made of fine
 matter.[12]



When human beings sleep, the sense organs continue to be impressed by
the species from sense objects; however, this impression, without the
attention of the soul, does not give rise to any act of perception
(DSF 203; Silva 2010), and it is arguable whether on these occasions
the image in the soul is actually made.



The theory raises the question about the correspondence between the
image made by the soul in imitating one received in the sense organs
rather than by taking in the species of the external thing. Kilwardby
dismisses that hypothetical objection by claiming that the sensory
soul is from the outset endowed with such a capacity and by restating
that the image does correspond to the external object.



The process includes a physically based account--the generation
of the species (which have different degrees of materiality), its
propagation through the medium, and its affection of sense
organs--and a spiritual/immaterial account that explains what
follows from the affection of the sense organ by the species.
According to this second account, the soul reacts to this affection
and makes the image of the object. It is this image that remains in
memory, available for acts of imagination.



Kilwardby insists at great length on denying any efficient causality
to the object, that is, he refuses to take perceptual acts as being
caused by the external object or its species. The object is the
necessary occasion and the *causa sine qua non* (otherwise
there would be nothing to be perceived) but not the sufficient cause
of perception (DSF 103; 123). The efficient cause per se of perception
is the immaterial soul--the division into sensory faculties is
instrumental to the process and in most of this part of the treatise
Kilwardby talks of the operations of the sensory soul (which he also
calls the 'incorporeal sensitive spirit') as a unified
entity.



Kilwardby's theory of sense perception is, on the one hand,
Aristotelian because he accepts that our knowledge of the world
originates in sense experience; he describes the process of perception
as a being-affected. On the other hand, it is Augustinian because he
limits the efficient role of the object to the affection of the sense
organs; he takes the soul to be the true efficient cause of
perception, reacting to the body's being affected and making in and
from itself the images of exterior objects; he grounds his theory on
the ontological assumption of a hierarchy of being where only things
at the same or higher level can affect each other, which forbids the
action of anything corporeal upon something incorporeal. The body
feels through the soul (and the soul through itself) because, as to
feel is a kind of being-affected, the body cannot affect the soul, but
the soul can affect the body.



Although much of his account of perception is made in terms of the
sensory soul and its operations and less in terms of faculty
psychology, it emerges from Kilwardby's account that a major cognitive
role is assigned to memory--a primacy found also in intellectual
cognition (where memory represents God, the Father, in the analogy of
the powers of the mind and in the Divine Trinity (see especially QLIS
35-37)). Contrasting Aristotle's and Augustine's views on
memory, Kilwardby argues that the power of memory is responsible for
receiving the images of objects of knowledge by natural assimilation,
for preserving the images of sensible objects, and for making them
available for the powers of imagination (sensory memory) and intellect
(intellectual memory) (QLIS 62, 181). Kilwardby distinguishes between
a sensory memory and a rational memory, further divided into inferior
(dedicated to sensible things) and superior (dedicated to the
intelligible objects) (QLIS 62, 179). The rational memory (the Father)
generates understanding by presenting the intelligible species to the
intellect (the Son; see QLIS 35; 37; QLIIS 77, 213-214).
Understanding is a form of a vision of an image generated by rational
memory, in the same way as an object generates an image of itself
(QLIS 35). In both cases, the soul has, in the first moment, the image
and in the second moment turns its eye (of the sensory soul and of the
mind) to see (know) the object.


### 5.2. Intellectual Cognition



Following Grosseteste, Kilwardby took human knowledge to comprise the
comprehension of the truth of contingently existing things, of what
frequently is in the same way, and of what has an absolute way of
being and is immutable--such as the principles and conclusions of
a demonstration. Of these, the highest type of knowledge is that found
in the conclusion of a demonstration (NLP I.5, 31-32).



Although we can know particular objects by means of perception, there
is *scientia* only of what always is in the same way (NLP I.10,
48), that is, of what is eternal and incorruptible; in other words,
*scientia* is about universals.


#### 5.2.1. Universals



The knowledge of universals is reached through induction from the
knowledge of singulars received through the senses (NLPA 171; DOS
196). Kilwardby describes the process in the following way: sensible
species are retained in the absence of a sensible thing by memory, and
from a multitude of memories arises experience, that is, a first
comparison of what is common to the species, not yet a universal. The
intellect is then able to discover the essential likeness
(*essentialis similitudo*) or common nature (*ratio
uniuersalis*) in which the sense data agree (NLP II.33,
503-504; DOS 7-8; NLPA 171-2). The universal is,
then, the essential reason for agreement of many images of the same
nature (QLIIS 78, 222.236-8; QLIIS 17, 71; Lewry 1978, 244).



In NLPor, Kilwardby describes the process of abstraction as the
interaction of two aspects of the intellect: the agent intellect
abstracts the intelligible species (*species intelligibiles*)
from the images of sensible things acquired through sense perception.
The intelligible species are then deposited in the possible intellect
(Lewry 1978, 241), which is bare or naked (*nudus*) previous to
this reception (QLIS 4, 12; QLIS 35, 83 and in DSF 14).



The universal is at rest in the soul, as it is the *ratio*
common to all those particulars which instantiate it (NLP 33,
504-505). Kilwardby argues that Peter and Paul differ as
individuals (they have their own matter and form), but they have
something in common--their essence. Universals are, therefore,
this agreement (*convenientia*) in essence. Two human beings
agree essentially agreeing in their humanity when that humanity is
considered not as individuated in this or that human being, but as
abstracted from any concrete individual (QLIIS 17, 71). The universal
is one thing (*res una*) not in the sense of being numerically
one (an individual thing) but in the sense of being a unity of
agreement or likeness of individual things outside the mind (QLIIS 17,
72).



It is this idea (together with individuation) that constitutes the
basis for Kilwardby's criticism of Averroes' monopsychism--a
theory he qualifies as being against faith and philosophy as well as
contrary to Aristotle's intention (QLIIS 78, 216). Averroes had argued
for his theory that there is only one soul (*una anima numero*)
common to all human beings with the contention (among others) that the
unity of the representative species requires the unity of the soul
(QLIIS 78,
 215).[13]
 Kilwardby argues against this idea, by claiming that the different
likenesses present in different souls are one only in species (QLIIS
78, 221), in the same way as individual human beings, such as Plato
and Socrates, correspond as species, that is, as human beings, not as
individuals. Those likenesses are numerically multiple according to
the multiplicity of souls in which they are received, but they
correspond to each other in being representations of one and the same
thing, for example, Plato (QLIIS 78, 218-219; see also QLIIS 17,
71). The same is valid for the universal, which is abstracted from
many similar likenesses, such as the likenesses of Socrates and Plato.
It is also (incidentally) multiplied according to the multiplicity of
intellects in which it exists. It is one only in species as the
*ratio* in which the many likenesses of the same nature
essentially agree (QLIIS 78, 222).



Therefore, sense perception and intellectual cognition are
complementary. Even though there are intelligible things that are not
sensory, all sensory things are intelligible (DOS 430-431): they
are known by the senses as particulars and ordered towards further
intellectual cognition (DOS 433). "Sensation is",
Kilwardby says, "the gate to human cognition", because
there can be no knowledge of universals (and demonstration) without
the knowledge of particulars (NLP I.33, 509; DOS 433).



Human knowledge proceeds from that which is acquired through the
senses, i.e., particular intentions, to the knowledge of that which is
more distant from the senses (DOS 627), that is, the common intentions
(*communes raciones siue communes intenciones*) which are
abstracted from them (QLIII1S 44, 189; see also see Lewry Por, 360).
Although acts of perception are about singular objects, it is by means
of sense perception that cognition of universals is accomplished (by
abstraction of those individuating circumstances) (NLP II.33, 505):
one perceives Callias, but we cognize Callias not as an individual
human being but *qua* human being as such. But one needs to
proceed from what is better known to us (that is, that which is
immediate in sense perception, the singular thing) to what is better
known by nature or more removed from the senses (DOS 238; see also NLP
I.7, 39; NSLP 18, 139-140), as scientific knowledge is not about
the particular object immediately perceived but the universal (DOS
436). We come to perceive first universals, then particulars, as when,
at a distance, we perceive first a body, then that it is an animated
body, then that it is an animal, and finally that it is this
particular animal--it must be said, though, as Avicenna points
out (says Kilwardby), that what is perceived in this process is a
confused universal (*universale confusum*), i.e., a universal
"fused together", as it were, (to use Peter King's happy
literal translation) with a particular (NSLP 18; see also NLP I.7, 40;
NLPor 11, M 9vb).



According to Kilwardby, universals exist, having different modes, in
and outside the mind (QLIIS 78, 218). The universal is one over many
(*unum preter multa*) according to *its own* essence
(*secundum suam essentiam*), but it exists in the many as
*their* essence (*secundum esse*) (NLP 33,
504-505). For him, a universal on account of its being universal
(*secundum rationem qua universale est*), can be
considered:



> 
> 
> (i)
> as existing in many individual things (*secundum concretionem
> et esse suum in multis*). Everything that exists outside the soul
> is either an individual, or it exists in an individual (QLIIS 17, 64),
> thus universals exist through and in individuals (QLIIS 18, 76; QLIIS
> 17, 70). Universals are corruptible incidentally, as their
> instantiations are corruptible (NSLPery I.2; NLP 21,
> 123-4).
> (ii)
> according to its essence, in abstraction from the many
> (*secundum essentiam sive abstractionem a multis*), that is,
> existing in the mind through abstraction from the individual things
> (QLIIS 78, 221; Lewry Por, 360; QLIIS 18, 74; DOS 10; 201; see also
> Piche 2002). As such, the universal exists only in the
> intellect (*est tantum opus intellectus et in intellectu tantum et
> non extra*). The form is the same *per essentiam*, but its
> being (*esse*) is different (DOS 200), as the universal is
> separable (by abstraction) from an individual thing according to
> intellectual being, but not in its natural, real being (NSLPor 7; NLP
> II.33, 504-5).
> 
> 



In a clear expression of his realist commitment, Kilwardby points out
that universals are not fictions of the mind: they are found in
individual existing things as their essences; otherwise there would be
no univocal predication or definition, and science would be about
fictions of the mind (QLIIS 17, 69; 73). Universals can be said of
many because they exist in the many that exemplify them (QLIIS 78,
220).



It is important to notice that Kilwardby rules out the association of
universals with divine ideas, as essences of things separate from
matter, as Plato claimed (*ut Plato posuit).* For him, such
ideas have no role in human cognition. In NSLPor 2 (M 2vb), he states
that universals exist in God's mind as exemplary and formal causes,
but science is about universals that exist in and are abstracted from
individual things; thus, the ideas (*ydee*) that exist in God's
mind from eternity are of no use to science (NLP I.36,
230-231).



As Kilwardby frequently remarks, following Aristotle's *dictum*
in the *Metaphysics*, human beings have a natural desire for
knowledge (DOS 6): *Omnes homines natura scire desiderant*.
Knowledge or more properly scientific knowledge (*scientia*) is
defined as the knowledge of the conclusion of a demonstrative
syllogism (based on Aristotle's doctrine in the *Posterior
Analytics*). As many other authors of the period, Kilwardby
distinguishes between the understanding of the principles
 (*intellectus*),[14]
 and the knowledge of the conclusion
 (*scientia*).[15]


#### 5.2.2. Truth



Truth, Kilwardby says, is an equivocal notion: the truth
(*ueritas*) of a thing is the thing's being (*esse*),
that is, what the thing genuinely is (NSLPery I.2, M 46vb; see also
NSLP 17, 130), namely, its essence or quiddity (*essentia vel
quidditas*) that is signified by its definition (QLIS 44,
 141).[16]
 Things themselves, and the forms or *intentiones* through
which things come to be known, lack any composition, that is, they are
neither affirmed nor denied, and therefore they are not true or false
as are declarative sentences (NSLPery, p. 16. See also NSLP 17, 124).
Truth is the correspondence of the thing and concept (*adequatio
rei et intellectus*), a definition Kilwardby takes from Avicenna
(NSLPery
 I.9).[17]



As the intellect is able to consider separately things that are
together and to separate things that are not together in reality,
truth and falsity have to do with the composition and division of the
species of things in the soul and not in extramental
 things.[18]
 That is to say, 'the composition and division that thought
brings about must have reference to the being and not-being of things
outside
 thought'.[19]
 Complex expressions are true in cases in which they conform to the
way the things are outside the combining mind, and they are signified
by the terms--the predicate and
 subject.[20]
 The intentions (*intentiones* or *passiones animae*) in
the soul and their combinations exist in the soul as signs
(*signa*) of extra-mental things.



Although the logician is not primarily concerned with the way things
 are,[21]
 he must know how they are in order to make statements that are true
with respect to the being of things outside the composing and dividing
mind (DOS 521), because logic does not teach how to reason in a
fictional mode (DOS 578). The one that combines or divides must know
the properties or modes of things in which things themselves agree or
disagree (DOS 577).



According to a common conception of truth, for a proposition to be
true, the actual existence of what is signified by its terms is
required; however, terms can also be considered without this
correspondence to something existing outside the mind(LPA I.18,
388-95). In NSLPery (I.7) Kilwardby considers the case of the
chimera:



> 
> 
> But it must be said that when I say that every statement is something
> of something, this 'something' is taken in a common way,
> either as something in speech only or in reality: thus when non being
> is stated in reality, it is a statement about being at least in
> discourse, as when one talks about chimeras or such
>  things.[22]
> 
> 
> 



A chimera corresponds at least to something in speech or in the
composing mind, even if not to something in the extra-mental
 world.[23]
 The word 'chimera' signifies what exists only in the
soul; therefore, its definition shows not the essence of a thing (as
there are no extra-mental things such as chimeras) but what the name
signifies (NLP II.7, 381-382).



The actual existence of things outside the soul is not always required
for a (affirmative) proposition (here understood as a statement-making
sentence) to be true (NLP II.7, 381). Nonbeing can be understood as
being not yet actual but in potency only, that is, that has an
aptitude to exist in
 actuality.[24]
 About those things that can but do not yet exist outside the soul,
existence is taken to refer to the (common) nature and not to the
individual (NLP II.7, 379): when animal is predicated of human being
or when one says that an eclipse is the privation of light, it is not
necessary to know whether or not this is actually the case because a
human being is always an animal, and an eclipse cannot be but the
privation of light. Thus, even if no human being actually existed
outside the soul, even then the proposition 'homo est
animal' would still be true (NLP II.7, 381).


#### 5.2.3. Signs



Kilwardby classifies signs into



> 
> 
> (i)
> natural signs, for example, smoke is a sign of fire and redness a
> sign of heat, and
> (ii)
> given signs; these divide into
> 
> 
> (ii')
> signs that have a likeness of the thing signified--these
> divide further into
> 
> 
> (ii'\*)
> those which are signs of something else, as spoken words are signs
> of the affections of the soul and the affections of things;
> (ii'\*\*)
> those which are signs of invisible grace, such as the sacraments
> (QLIVS 42, 225-26)
>  
> (ii'')
> signs that do not have a likeness of the thing signified.
>  
> 
> 



Of those signs that are signs of something else (ii'\*), some
signify by convention (*ad placitum*, which Kilwardby proves by
their not being the same for everybody); others signify naturally
(like the sounds of non-rational animals). Of those words that signify
by convention, some are simple expressions, and others are complex
expressions (*oratio* or *enuntiatio*). Only
significative complex expressions are true or false; simple
expressions are neither true nor false (NSLPery I.2).



Signifying by convention is the result of an original (voluntary)
imposition of a *significatum* upon a word, primarily conceived
of as a spoken word (*vox*) - a modulated sound (DOS 488;
see also QLIVS 42,
 224).[25]
 A word signifies the *passio mentis* and the thing outside the
soul (QLIVS 11, 47). Spoken words signify primarily the *passio
animi* (or *species intelligibilis* or
*intellectus*; Lewry Pery, 289) and signify things via thoughts
*(uoces sunt note intellectuum, et sic rerum)* (QLIS 144, 143).
The *passio*, being a likeness of a thing in the
mind--received rather than made by us--is common to all
human beings (LPA ed. 1516, 82rb).



Kilwardby argues that only human beings proffer meaningful utterances
because, as Priscian points out, the articulate vocal sound (*uox
articulata*) uttered by humans is tied together
(*copulata*) with a *sensus mentis* or
*intellectus* in the mind of the speaker; thus only beings that
have minds can produce significative
 utterances.[26]
 Moreover, the production of the *vox litterata* requires the
control of the modulation of sounds--what Kilwardby calls the
figure in the air (through which the utterances are
transmitted)--on a regular basis, that is, always the same figure
for the same word. This is done by the sensory soul under the control
of the rational soul (NLPA, 124-125). This explains not only why
meaningful articulate vocal sounds are signs but also their primacy as
efficiently caused by the soul (see Mora-Marquez 2014).



There are, therefore, two aspects of spoken language: on the one hand,
the *vox,* as an articulate sound, causes a natural change in
both the medium and the ear of the one who hears it (DOS 147; NLPA
127-128); on the other, the utterance, as something heard,
brings about an act of the intellect of the listener (DOS 425; NSLPery
I.1). To speak (*dicere*) in the proper sense means expressing
the likeness of a thing in order to make known that of which it is the
likeness (QLIS 37, 106). In that sense, a meaningful utterance should
be called 'nota' with respect to the speaker, because it
refers to the meaning conveyed by the speaker (the *species
intelligibilis*), and it should be called 'signum'
with respect to the one who hears it, because it refers to the
material/sensitive aspect of the sign (NSLPery I.2; see Lewry 1978,
289; Rosier 1994, 97-98; Marmo 1997, 139-40). As noted by
Rosier, Sirridge, and Kneepkens (see Bibliography), one of the main
contributions of Kilwardby (and Bacon and others in the intentionalist
grammatical tradition) is the emphasis on two levels of completeness
of speech: one, concerning the word's modes of signifying and the
other concerning the way the hearer understands or interprets the
intention of the speaker (*intentio proferentis*).



One consequence of the conventional nature of language, according to
which the relation between a sign and a significate is imposed on the
sign by a voluntary act on the part of the *impositor*, is that
the change in what is signified by the sign does not require a change
in the sign (NLPery I.1; Lewry 1981). On the other contrary, in the
case of natural signs, such as paleness from fear or redness from
shame, the change in the thing signified implies a change of its
 sign.[27]


#### 5.2.4. Logic and Demonstrative science



Kilwardby adopts Robert Grosseteste's distinction between four main
senses of 'to know' (*scire*: (i) in a general sense, the
comprehension of the truth of contingent things, (ii) in a common
sense, the comprehension of the truth of things that often are, (iii)
properly, the comprehension of the truth of things that are immutable,
(iv) most properly, the comprehension of the truth of things that
always are the same and the truth of which depends on what is prior
(NLP I.5; Silva 2012, 216; Corbini 2013, 166). So, whereas in a sense
to know can be said of sense perception, it is properly and most
properly said of what is universal and of what is necessary (DOS 379).
Such knowledge is found in the premises/principles and above all in
the knowledge of the conclusions of demonstrations (iii and iv,
above). Scientific knowledge (*scientia*) is then more properly
demonstrative reasoning (DOS 381).



A demonstration is a syllogism that brings about knowledge (NLP I.5,
31). A syllogism is "an expression in which a conclusion follows
of necessity when certain things have been asserted" (DOS 493,
Kretzmann 1988, 265). The material principles of the syllogism are the
three terms (remote matter)--the two extremes (major, minor) and
the middle--combined into two premises (proximate matter). The
conclusion is not part of the syllogism.



A demonstration must have as starting-points appropriate principles
(NLP I.19, 106-7): true, first, immediate, prior to, better
known than, and causes of the conclusion (NLP I.6, 34; DOS 503; 558).
Of these conditions, to be true, first (or primitive), and immediate
are the central ones: first because there is nothing prior to it in
its kind--otherwise the source of scientific knowledge rests on
an infinite series of demonstrations (NLP I.8, 43; I.11, 53);
immediate because there is no medium between the subject and predicate
(NLP 6, 38). Whereas to be true, first, and immediate are the
qualifications that concern what the principles are in themselves (and
thus the ones which belong to their definition), the others--for
example, to be better known--qualify the principles with respect
to the conclusion (NLP I.8, 44; I.10, 49).



Kilwardby presents the following division of the first principles (NLP
I.9, 45):



> 
> 
> (i)
> *dignitates* (axioms), principles common to all sciences,
> such as the principle of noncontradiction (*De nullo eodem simul
> affirmatio et negatio*) and the law of the excluded middle (*De
> quodlibet affirmatio vel negatio...*) (DOS 584; NLP I.25,
> 152). A *dignitas* does not require any external reason
> justifying it; it is immediately understood by the
>  intellect;[28]
> (ii)
> *positio*, the principle proper to a particular science.
> All particular sciences (*scientie speciales*) share the common
> first principles (*communia principia*), but they have their
> own set of first principles (*propria principia*; NLP 25, 152).
> The *positio* further divides into *suppositio*, that
> is, a proposition that states of something that it is or it is not,
> and the *diffinitio*, that is, the definition of the
> subject-matter of a science (QLIS 7, 18). A definition expresses the
> essence of a thing (NLP II.3, 346; QLIS 44, 141) and what is indicated
> by its name (NLP I.9, 45); it is not a proposition because it does not
> say of something that it does or does not exist. Therefore, a
> definition enters into a demonstration as a part of a
> principle/premise (NLP I.9, 46).
> 
> 



Kilwardby denies (NLP II.33) that the first principles of
demonstration are innate or demonstrable. Kilwardby argues, instead,
that they are acquired from pre-existing sensory knowledge (NLP II.33,
506). The knowledge of propositions must be preceded by the knowledge
of the terms that enter into its composition, that is, what it is that
is predicated and what the thing is of which something is predicated
(NLP I.2, 16). By abstraction the intellect comes to know the
universals that function as subject and predicate in syllogistic
propositions.



These principles are known by themselves (*sunt per se nota*)
(DOS 331; 503; QLIII2S 1, 7); our certitude of them, Kilwardby says,
comes from the 'light of truth' (QLIS 12, 31). It is by
the same light of truth that one assents to the principles/premises
from the knowledge (*notitia*) of the terms that constitute
them as well as to the conclusion from the premises (NLP I.11, 54).
This act of assent is the result of some kind of illumination from the
soul's cognitive powers (QLIII2S 1, 7). The conclusion, he asserts, is
the terminus of the act of intellectual cognition, but the middle term
is what makes it possible, just as light makes bodily seeing possible
(QLIII2S 5, 18-20). One assents to the conclusion because one
comes to see how the middle term leads to the conclusion and makes the
conclusion worthy of assent (QLIS 13, 33.2-3; see also DOS
472).



In the highest type of demonstration, the *potissima
demonstratio*, the middle term is a causal definition (NLP II.3,
343.12-14; DOS 527; LPA prologue) and the definition of the
predicate (NSLP 6, 29; DOS 563). The middle term allows for the
demonstration of the predicate to belong *per se et propter
quid* to the subject (NLP I.20, 117). The paradigmatic
demonstration is a syllogism of the first figure in the first mood,
that is with two universal premises because the relation of necessity
between premises and conclusion is more evident (see Thom 2013,
144-47).



It is not, however, enough for a principle of demonstration to be
true; it must also be necessary. A necessary conclusion follows from
necessary premises (NLP I. 19, 110-113). The kind of
universality required for demonstration is not the same as that of a
universal acquired through abstraction, which is said of many (*ut
dicatur de multis*)--the kind described in the
*Perihermeneias* and in Porphyry's *Isasoge*--but
the universal that must be said of all and always (*de quodlibet et
semper et
 primo*).[29]
 The kind of necessity Kilwardby has in mind is what applies to all
(things under the subject), on account of what they are, and it is
universal (*de omni*, *per se*, and *universale*)
(NLP I.12, 62).



There must, however, exist a science whose aim is to discover and
teach the method of how to investigate, through correct reasoning,
what is not known from what is known. It cannot be metaphysics because
this science regards things apart from motion. A syllogism, however,
is a kind of motion where the properties are deduced from the
subject(-matter) and the conclusion from the premises (NLP prologue,
4). That science is logic. Since logic has the task of discovering a
method of knowing that can be used by all sciences (LPA prologue),
logic is thought of as the *modus scientiarum*, or the science
of sciences (*scientia scientiarum*). Proficiency in the way of
reasoning allows for the discovery of truth in every field of inquiry
(DOS 419), even though every science demonstrates according to the
possibilities of its matter (NLP II.34, 512). In order to accomplish
this task, logic needs to teach how to combine one term with another
(or divide one from another), the species of combinations and
divisions corresponding to the species of propositions or statements
(DOS 517). Logic also relates things to one another by means of a
middle term in the syllogism, which is logic's subject matter.



The different operations of the intellect producing different
linguistic units are studied in Aristotle's different logical works:
the simple significative expression (*simplex sermo
significativus* or the *dicibile sine complexione*),
significative of one of the ten genera of things, is the
subject-matter of the *Categories*; the declarative sentence
(or the *dicibile ordinatum cum dicibili interpretatione
enuntiativa*) is dealt with in the *Perihermeneias*; and
the syllogism (or the *dicibile ordinatum cum dicibili in
complexione duorum extremorum*) in the *Prior Analytics*.
The syllogistic form--which Aristotle presents in the *Prior
Analytics*--can then be applied to any matter whatsoever,
probable or necessary (DOS 502). The *Posterior Analytics*
presents the demonstrative syllogism, made of necessary matter; the
*Topics* the dialectical syllogism of probable matter; and the
*Sophistical Refutations* deals with sophistical matter, i.e.,
fallacious reasoning (DOS 503).



Now, logic considers things in one of two ways: in terms of first
intentions, that is, as the things themselves and thus belonging to
one of the ten highest kinds of being--the categories; in terms
of second intentions, that is, things as considered by the intellect
and in respect to other things (DOS 459). They are called first and
second because only after knowing things themselves can we consider
their mutual relations (DOS 459): second intentions are about first
intentions. 'Substance', 'quality', and such
are names of first intentions, whereas 'universal',
'particular', 'to be an antecedent', 'to
be a consequent', and such are names of second intentions.



Kilwardby discusses second intentions in the context of a distinction
he proposes between reasoning as a subject of a discipline (logic) and
as an instrument which is common to all disciplines (DOS 455; LT 39,
125). Reasoning in one and the other case is the same from the point
of form, since the moods and figures are the same; but it is different
in respect to matter (probable and necessary, DOS 500-504). As
an instrument, reasoning is about things themselves--those that
belong to their subject matters, such as lines and figures in
geometry--because the subject matter of particular disciplines is
things (DOS 455; 477). By comparison, as the subject matter of logic,
reasoning makes no reference to things themselves but to their
accounts/reasons (*rationes rerum*), that is, the modes by
means of which they are reasoned about (DOS 463). The logician is not
concerned primarily with things themselves, the *res naturae*
or first intentions, but with the *res rationis* or second
intentions; that is, he is not concerned with the things signified by
the subject and predicate terms of a proposition but with subject and
predicate as such (QLIS 90; see also NSLP Prooemium, 4; 5, 20; Pini
2002, 21-22).



Things themselves - things that fall into one of the
categories--are not in our soul, only their accounts
(*rationes*) are (DOS 448-49). These modes or accounts
(*modi rerum sive rationes*) are abstracted from things and
compared to each other as if they were the things themselves being
compared (DOS 451). It is the mode or account of things that makes it
possible for us to reason about them (*faciunt res
rationalibes*: DOS 450; *rationes rerum et modi per quos res
sunt rationabiles*: DOS 463). Logic then considers the *modi
sive rationes rerum*, the properties of things in so far as they
are thought or compared to one another, which enables combining them
into propositions and demonstrations and arriving at scientific
knowledge (*scientia*). (See DOS 449) Without the consideration
of things together with the *rationes rerum*--for example,
that 'divisible' is more universal than
'line'--no reasoning could be done about them (DOS
450).



Reasoning needs to be considered as independently as possible from any
particular subject matter because logic examines the method of correct
reasoning, which can then be taught and applied to all the other
sciences (the syllogism *simpliciter* has matter, premises, and
terms. In that sense, they can be replaced by transcendent matter,
such as A, B, C; each particular science then replaces the terms with
its own subject, properties, causes, and so on--DOS 452. In that
sense also, the syllogism *simpliciter* is not productive of
knowledge or belief--LPA prologue (see Thom 2013, 140).



Thus, Kilwardby's meaning of first and second intentions cannot be
confused with the meaning these terms acquire later on. His use of
second intentions as proper to logic shows how he understands this
notion in the context of his theory of reasoning and of logic as being
the science of reasoning--that is, it studies the process of
reasoning in such a way that it can be used by all the other sciences
as an instrument for the discovery of truth.


## 6. The Classification of sciences in the *De ortu Scientiarum*



Kilwardby adopts a scheme of ordination for the different sciences or
disciplines, and it is largely based on the model of Hugh of St.
Victor's *Didascalicon: De studii legendi*, a widely circulated
and immensely influential work from the twelfth century on the
classification of sciences (see Silva 2013). As with the work of his
(Augustinian) predecessor and notable influence, the DOS had a fame of
its own and remains one of the most relevant medieval works of its
kind.



Hugh's *Didascalicon* (itself inspired by previous
classifications--see Weisheipl 1965) however only allows for
Kilwardby to include the sciences in what is called knowledge--to
this he must (and does) add the principles of the division of the
different sciences into various fields of inquiry and then the
classification of the different sciences within a certain field of
inquiry. Kilwardby goes beyond Hugh and previous classifications not
so much with regard to the principles of division and classification,
but rather with regard to what is implied in science--that is to
say, with regard to the necessary requirements for something to be
considered scientific in a certain field of inquiry and process of
discovery according to the Aristotelian deductive model of science.
Any science (not
 art)[30]
 needs to fulfill three main requirements: first, it should have a
subject matter (DOS 167; 221); second, it should present the parts and
species of a science's subject matter and their properties (DOS
650-652); third, it should take into account the first common
principles of demonstration and have a set principles appropriated to
its genus (NLP I.23).



The *modus sciencie*, according to the prologue of his NLPery,
"consists of the speculation about the proven properties of the
parts and species of the subject matter" (Lewry Pery, 382; see
also NLP prologue; LT 50, 125), which is done by means of definition,
division, and collection. By means of division one comes to know the
subject of a science; through collection or reasoning one comes to
know the properties of the parts and species of the subject; from
definition, one comes to know the parts and species of the subject
(DOS 524-525; QLIS 7, 18-19).



A major difficulty is whether one and the same
science--metaphysics--can have such two distinct objects as
God and creatures, still respecting the principle of the unity of
science (DOS 221; see also QLIS 4). In DOS 226 Kilwardby claims that
unity by analogy is sufficient for the science of being qua being
(*scientia de ente*), metaphysics, to be the field of inquiry
that has God and the creatures as objects of inquiry. Being and
substance can be predicated by analogy of God and creatures: of God
primarily and properly, of creatures in a participative and less
proper way. God cannot be known directly, but He can be known by means
of His effects and by negation, in the same way our bodily eyes do not
see themselves except through a mirror (DOS 225).



A major issue in the division and classification of disciplinary
fields is the relation between subaltern sciences. In DOS 324
Kilwardby advocates three criteria for subalternation:



> 
> 
> (i)
> The subject matter of the subaltern science falls under the
> subject genus of the subject matter of the subalterning science.
> (ii)
> The properties of the subject of a subaltern science can only be
> proven by means of the properties of the subject genus of the
> subalterning science (DOS 330), by adding something of another genus
> in nature that is, however, somehow essential to the subalternate
> science. For instance, the knowledge of 'triangle' and
> 'isosceles' belongs to one and the same science even
> though 'isosceles' is something in addition to the
> geometrical demonstrations of the properties of 'triangle'
> (DOS 329).
> (iii)
> Demonstrations of subaltern sciences must be made within the same
> subject genus of the subalterning science, that is, a property of
> something belonging to one genus cannot be demonstrated from a thing
> belonging to another genus--for example, a geometrical
> proposition demonstrated by means of arithmetic (NLP I.21, 120).
> Moreover, each subalterning science has a set of first principles that
> are used as starting points for all the subaltern sciences. For
> example, the properties of numbers of harmony can only be known
> through the knowledge of the properties of number *simpliciter*
> (DOS 330).
> 
> 



One example of this subordination is found in the relation between the
science of geometry and its subordinate sciences. Geometry is the part
of speculative philosophy dedicated to the study of limited magnitude
(finite limited quantity abstracted from natural matter), its parts,
and their properties (DOS 64-65). Astronomy and optics are two
such subordinated sciences. Astronomy is a speculative science that
has as its object the magnitude of celestial bodies and the distance
between them (DOS 72), whereas optics is defined as the speculative
science that has as its object the diverse modes of vision, focusing
on the nature of visual rays. It belongs to the genus that is the
subject matter of geometry because the visual rays propagate
rectilinearly (DOS 77).



Kilwardby begins his text in a clarifying manner of distinguishing
between those sciences that are about human words and actions and
those that are about what is divine (DOS 1; 654). The science of the
divine is theology, focused on the study of the Sacred Scripture. Of
the human sciences, some are commendable (philosophy), others vicious
or illicit (magic). In DOS, Kilwardby is mostly concerned with the
sciences of human invention. He further divides philosophy into
speculative--the name that designates a group of sciences
constituted by physics, mathematics, and metaphysics--and another
group classified under the heading 'about human things',
that is, the results of human intentionality (QLIS 90, 286); it
includes the active sciences and the sciences of language. The former
divides into mechanics and ethics, the latter into grammar, logic, and
rhetoric. Mathematics includes the sciences of the
*quadrivium*, that is, the four sciences of things as they were
known in the Middle Ages (geometry, astronomy, music, and
arithmetic).



Science, in the sense of knowledge, falls into one of three kinds: (i)
that which is primarily oriented to and necessary for salvation; (ii)
that which is useful in the search for truth and righteous
living--for living an honest life--but not sufficient for
salvation; (iii) that which is useless in both respects and is
connected with vanity (DOS 1-2). This grouping obeys a general
principle, originated from Augustine, which sets up the direction for
medieval learning: knowledge must be directed towards virtue (DOS
639). This same aspect is also present in the consideration of the
order of the sciences, in which all sciences are preparatory to the
science of the higher end: all sciences are subordinated to, or at the
service of (*famulantur*), theology.



Kilwardby's criterion for classification is the object of the sciences
(Alessio 2001, 108-9): "science must be divided according
to the division of things about which it is" (DOS 5). "The
diversity of sciences", he says, "results from the
diversity of their subject matters" (DOS 108). Sciences are
organized, as in the Boethian scheme, according to the level of
abstraction of their objects of study from matter. Speculative
sciences rank highest (DOS 203) and among them metaphysics.
Metaphysics deals with being without qualification
(*simpliciter*), whereas mathematics and physics deal with
particular kinds of being (DOS 323; NLP II.11, 417). Metaphysics
considers substance and its principles - matter and form -
per se, that is, apart from change and privation, whereas physics
(natural philosophy) considers substance as mutable and therefore
matter and form (and privation) as principles of change (DOS 232);
mathematics deals with changeable material things but not insofar as
they are material, rather, insofar as they are abstracted from motion
(within the sciences of the *quadrivium*, where the order is
astronomy, geometry, harmony, and arithmetic).



In chapters 63 and 64, Kilwardby discusses different ways to consider
the order of the sciences: (i) the order of discovery, (ii) the
natural order, (iii) the ordering according to ends, (iv) the order of
the degree of certainty, and (v) the order of teachability.



According to (i), the first among the (arts and) sciences are the
mechanical arts because they result from the necessity to assist human
beings in surpassing their natural physical constraints (DOS 358).
Human beings are, in comparison with other animals, weaker in body,
and therefore tend to devise forms to surpass this deficiency (DOS
626); but they are gifted (by God) with reason to discover ways to
surpass their physical limitations (DOS 360-61). The
sub-divisions of the mechanical arts obey the principles laid out in
Hugh of St. Victor's *Didascalicon*--as Kilwardby himself
makes explicit (see DOS, chapters 37-39). Special attention must
be paid to the similarity between the scheme of the seven liberal arts
and the seven mechanical arts that Hugh defends and Robert follows
(DOS 363): as the liberal arts divide into *trivium* (sciences
of language) and *quadrivium* (sciences of things) the
mechanical arts also divide into a group of three arts concerning
those things related to what is external to the body (*extrinsecus
corporis*)--clothing, weaponry (further divided into
architecture and industry), and navigation--and a group of four
arts focusing on what is internal to the body (*intrinsecus
corporis*)--agriculture, hunting, medicine, and theatre.



Next comes speculative philosophy, and here the order is physics,
mathematics, and metaphysics. This order is established on the basis
of the proximity of each to the senses, from closest to most distant
(DOS 627). The end of the speculative sciences is truth (DOS 394),
that is, to know the way of natural things according to their natures
(DOS 405). Then comes ethics (DOS 628), the science that considers the
human operations in connection with the mortal human body (DOS 404),
followed by the sciences of speech/language, which have an order
themselves: grammar, rhetoric, and logic.



Kilwardby offers a two-fold consideration of logic, in a stricter and
in a broader sense. In the broader sense, logic is a science of speech
(*scientia sermocinalis*), dealing with correct expression,
including grammar, rhetoric, and dialectic (logic in the strict
sense). In the stricter sense, logic is the science of reasoning
(*scientia rationalis*) (DOS 492). Logic is the science of
reasoning because it considers and teaches the discovery of terms,
their organization into complex expressions, and the combination of
complex expressions into syllogistic demonstrations; but it is also
the science of speech because it deals with the linguistic expression
of reasoning--which does not remain, as Kilwardby says, hidden
(inchoate) in the mind (DOS 578): mental words are about things,
spoken words are about mental words, and written words are about
spoken words (DOS 593).



The sciences of speech divide into those that are significative of
what is known (grammar) and those that are inquisitive about what is
not known (logic and rhetoric) (DOS 468). Rhetoric differs from logic
in that the former is about hypotheses and what is particular, whereas
the latter is about theses and what is universal--its subject
matter is the syllogism and its species (DOS 468; 471; 474). By
contrast, rhetoric, as the science of speaking well, presupposes
grammar--the science of signifying correctly (DOS 629). The
subject matter of grammar is significative speech qua significative
(DOS 474), that is, the *oratio* and its parts insofar as they
signify or co-signify (DOS 489). Speech (*sermo*) here means
the human *vox* as it signifies by convention (*ad
placitum*) (DOS 488). Grammar considers the sentence from the
point of view of how well it is formed or its congruity
(*congruitas*), which is the result of how its elements are
correctly ordered to one another, rather than of the correspondence of
those words with the things they signify (NSLPery I.5). The end
(*finis*) is to teach how to correctly express the conceptions
of the mind (DOS 483-84; 490). Kilwardby's willingness to grant
a scientific role to grammar is notorious (Rosier 1994; Sirridge
1988).



Natural order (ii) is the order of the subject matter, that is, the
degree of abstraction: first the speculative sciences, then active
sciences, and finally the sciences of language (DOS 630-635).
(According to this criterion, the order among the sciences of language
is: grammar, logic, and rhetoric; this order is found already in the
prologue of the NSLP).



The third type of order (iii) is the order of the end (*finis*)
or the ends of the different sciences. Among the sciences, ethics is
the first from this point of view, followed by the speculative
sciences, and then the sciences of language. (According to this
criterion, the order among the sciences of language is: logic,
rhetoric, and grammar.) Speculative knowledge is ordered to ethics in
the same way as truth is ordered to the supreme good (DOS 405; see
Celano 2013, 340).



The next criterion (iv) is according to the form or the degree of
certainty achieved. According to this, the first among the sciences
are the speculative - and among them the highest
(*certior*) is mathematics (NLP II.34, 512) - followed by
the active sciences - and here ethics is prior to mechanics.



The final criterion (v) is the order of teachability. According to
this ordering, the sciences of language come first--and grammar
first among them--followed by the speculative and active
sciences--ethics first, then mechanics.



To conclude, Kilwardby's classification includes elements from
previous classifications, but the overall result is quite original:
(i) the inclusion of logic, as a branch of science about human beings,
within the active sciences; (ii) the Aristotelian inspired division
between theoretical or speculative philosophy--which encompasses
physics, mathematics, and metaphysics--and practical
philosophy--which comprises ethics and divides further into
monastic, economic, and political; (iii) the inclusion of the
mechanical arts (from Hugh of St. Victor) within active or practical
philosophy.


## 7. Celestial motion and time



In 1271, Kilwardby, together with Thomas Aquinas and Albert the Great,
received a questionnaire sent by the Master General of the Dominican
Order, John of Vercelli. The questionnaire, constituting 43 questions
to be answered in a systematic order (*forma* *taxata*),
surveyed a wide range of theological problems, but the majority (25)
was concerned with the movement of the celestial bodies, its causes,
and the possible influence upon the inferior (terrestrial) bodies. It
includes questions such as: Does God move any body immediately; if so,
by a continuous everlasting movement, by a continuous but not
everlasting movement, or by an instantaneous motion? (Q1) Are angels
the cause of the movement of the celestial bodies? (Q2)



The fifth question inquires about the cause of celestial motion.
Kilwardby considers three possible answers that he considers to be
either (a) philosophically correct, (b) not to be approved either by
philosophy or by the saints, or (c) in agreement with philosophy.



> 
> 
> (a)
> According to Aristotle and others, celestial bodies are animate
> beings that have intelligence and move by the power of will, in the
> same way as human bodies are moved by their souls (D43Q 2, 14).
> Kilwardby himself defends this view in his LSP and DOS (Lewry 1978,
> 324-5; DOS 20).
> (b)
> Celestial bodies are moved by angels. Kilwardby dismisses this
> answer by arguing that the motion of the celestial bodies needs to be
> natural, in other words the principle of motion must be internal to
> the thing moved (if the cause is external, the motion is violent)
> (D43Q 2, 12; see also E 2, 24-25). If angels moved celestial
> bodies, their motion would be violent. In spite of this objection,
> Kilwardby leaves open the possibility for this view, diplomatically
> stating that because he does not know, he cannot assert it (*quia
> nescio, asserere nolo*) (D43Q 10, 19; 15, 21).
> (c)
> According to some, the cause of the motion of the celestial bodies
> is their own weight and inclination (*instinctu propriorum
> ponderum*: D43Q 3, 192), in the same way as heavy and light bodies
> are moved by their own weight and inclination (*propriis ponderibus
> et inclinationibus*: D43Q 2, 14).
> 
> 



In Kilwardby's own words:



> 
> Just as heavy and light bodies are moved to a place in which they rest
> by their own inclinations and tendencies, so celestial bodies are
> moved circularly in place by their own inclinations similar to the
> weight (*quasi ponderibus*) in order to conserve corruptible
> things, lest they suddenly perish and fail. (trans. Weisheipl 1961,
> 315).
> 



Kilwardby's theory is, however, not absolutely original, as scholars
(in particular Weisheipl) have shown. In fact, some sixty years
earlier, John Blund argued for the same explanation in his
*Tractaus de anima* (paragraph 10); here he stated that heaven
(including all celestial spheres) is moved by nature and not by the
soul or celestial beings. This view seemed to go unnoticed until
Kilwardby referred to it; originality claims apart, the significance
of Kilwardby's statement must be emphasized. The interest of his
solution is in how it harmonizes a natural explanation for the
phenomenon of celestial motion - designating the instinct of
their [the celestial bodies'] own weight as its cause - while at
the same time it safeguards God's influence in the natural world: God
is not the direct mover, but the one who endows these bodies with
their instinct (D43Q 2, 14; see Silva 2007 for references).


### Time



One of the questions Kilwardby addresses in his treatise *On
time* (*De tempore*)--written most probably after
DOS--is whether time, as the measure of motion, is defined in
relation to the diurnal motion (DT 35), a view identified with
Averroes. The aim of his treatise is to understand time in such a way
that it reveals compatibility between Aristotle's (*Physics*
IV, 10-14) definition of time--which Kilwardby calls
'physical'--as relative to motion (and motion
relative to continuous quantity) and the Augustinian
(*Confessions* XI) definition of time--which he calls
'metaphysical'--as an extension (*distensio*)
of the mind, thus existing only in the mind (DT 10-11).
Kilwardby's solution is to argue for a distinction between
indeterminate and determinate time: on the one hand, indeterminate
time exists outside of and independent from the numbering mind (it is
neither numbered nor measured) as, prior to any measuring, that which
is measured is already in motion (DT 77). Determinate time, on the
other hand, has existence in the mind only, as it can only exist in
the measuring mind. In Kilwardby's own words, "time comes into
existence when we perceive the direction of that which is earlier and
later in motion" (DT 77). Time is, therefore, the measure not of
any specific motion but the measure of motion (DT 42) defined by an
instant before and an instant after. The quantity of motion between
these two instants, before and after, has a numerical expression (DT
34), and this number is then used to measure all other motions (DT
49): time "measures the whole motion by determining the motion
which will measure the whole" (DT 27). Time is the number of
motion because number is the appropriate name for that
 measure.[31]
 We determine time by measuring motion according to fixed measures
(days, hours, and so on) (DT 77). As the measure for any kind of
motion, time has unity.



Time, hence, is dependent for its definition on motion (NSLP 7, 54).
The continuous nature of motion is essential to guarantee the
continuous nature of time (DT 12). Time needs to be continuous for it
to measure continuous motion (NSLP 8, 58). The continuity of motion,
in turn, is guaranteed by the continuity of the parts that constitute
the moving thing (DT 17). Kilwardby argues that time and motion are
exceptions to the rule according to which the parts of composite
things must exist simultaneously; instead, he claims, that they are
composite transient things, and the parts of time are successive (DT
7-9). Time has its being from the ordination of its parts into
before and after (NSLP 8, 58). The instant (the now: *nunc*) is
from the point of view of the substance which is always the same but
different in the manner of its existence (DT 89). Time is the measure
of continuous motion, and the instant is the measure of one of the
moments of that continuous alteration (DT 94-95). For Kilwardby,
celestial motion as measured by time is the standard for measuring all
other motions (see Trifogli 2013; for other aspects of Kilwardby's
treatment of time, namely the connections to his contemporaries, see
Porro 1996.)