I. Auspicious Beginnings

The history of the scholarship of medieval philosophy is full of pioneering figures who recognize thinkers and aspects of their thought as being of historical significance. One needs just to remember the figures of Marie-Dominique Chenu (1895-1990), Étienne Gilson (1884-1978), and Norman Kretzmann (1928-1998), to name just a few. Much of what we know of philosophical ideas in the medieval period and how we understand the main patterns of their development is due to their work – not limited to but inspired and made possible by their efforts in carving new inroads for others to pursue. The list is certainly longer, and one always runs the risk of being unfair when it comes to whom to include in such a selection, so that in the end, it becomes a personal affair, revealing preferences for those who have made a bigger impact on one's own research careers and interests. Speaking for myself, the name of Patrick Osmund Lewry will always figure in such a list. I never met Lewry, but it was after reading his edition of Robert Kilwardby's De spiritu fantastico Footnote ¹ that I understood where my research interests lay, and this has since then defined to a large extent my own scholarly pursuits.

Cardinal Robert of Kilwardby OP died on September 10, 1279. Father Patrick Osmund Lewry OP died on April 23, 1987. Despite their many centuries apart, much connects the two men, from their studies and teaching at Blackfriars, Oxford, to their interest in (medieval) logic: Kilwardby producing a variety of treatises on logical theory of enduring impact among his contemporaries and others in the centuries to come; Lewry devoting his scholarly life to the study of medieval logic, in particular in the Oxford academic milieu, and above all to the study of Kilwardby's thought.Footnote ² To him, we have a systematic analysis of these works, well-reasoned justifications behind attributions of authorship to Kilwardby, and a better understanding of the early reception of Aristotelian works in England in the thirteenth century.

Robert Kilwardby was Master of Arts at the University of Paris from the mid-30's to the mid-40's of the thirteenth century, during which he wrote on a variety of topics, including logic, theory of language, grammar theory, theology, philosophical psychology, natural philosophy, rhetoric, and epistemology. Like Lewry, I take it that what makes Kilwardby so important as an object of study for those who want to understand the evolution of medieval thought is that he wrote at a time when newly translated works of Aristotle on natural philosophy, ethics, logic, and epistemology were slowly settling in the cultural and academic institutional settings of the Latin West. The efforts to receive and interpret these works would change the nature of science in all domains until the dawn of modern thought, and in Kilwardby's work we can read how this intellectual framework was being understood and diversely interpreted in this period of transition, before it was completely transformed by outstanding interpreters such as Albert the Great (ca. 1200–1280) and Thomas Aquinas (1224-1274), from the Dominicans, and John Duns Scotus and William of Ockham, from the Franciscans. Kilwardby is the last of the least major figures before the advent of Scholasticism as we know it, and his contribution to this system of thought defines his place in history as one of the great medieval thinkers.

After his Parisian period, Kilwardby entered the Dominican Order just before or upon his arrival in England, around 1245, some twenty-five years after the establishment of the first house of the Order in England at Oxford (in 1221).Footnote ³ After studying Theology, probably with Richard Fishacre, he continued as a regent master of Theology at the University of Oxford and went on to take increasingly more important places within the hierarchy of the Order and the Church, first as Provincial of the Dominican Order in England (1261), then as Archbishop of Canterbury (1272), and finally as Cardinal of the Roman Catholic Church in Porto and Santa Rufina (1278).Footnote ⁴ His influence and impact upon other major figures of the period has been extensively noted, for instance, on his brothers Albert the Great and Thomas Aquinas, but this impact was not only positive. In fact, much of the reason why Kilwardby has been neglected for so long is the criticism he has been perceived as leveling against Aquinas – although the extent of this criticism has been repeatedly called into question.Footnote ⁵ To characterize their intellectual disagreements as ‘hostile’, as has often been done in the past, is mostly unfair and overlooks the nature of medieval philosophical debates: medieval thinkers, like their modern counterparts, often disagreed on how best to interpret a certain theory and on how to read a difficult passage. This was particularly the case in the early reception of Aristotle and his theories about the nature of matter and the human soul, which caused problems in how to understand them in the context of Christian ideas of creation, immortality, and resurrection. Kilwardby and Aquinas found themselves, somewhat willingly, at opposite ends of the debate and, just as it is true that Aquinas ended up being on the winning side, it is equally true that he was most likely representing a minority view at the time Kilwardby wrote the majority of his works.

The impact of his modern Dominican brother, Osmund Lewry, on medieval scholarship cannot be overestimated and mimics the influence Kilwardby himself had on the development of medieval thought. From around 1978, when he published his magistral PhD dissertation at Oxford, to around 1988, when the last of his posthumous publications came out, Lewry published on Kilwardby's psychology, theory of knowledge, philosophy of time, grammar, logic, rhetoric, theology, ethics, and cosmology. Lewry also produced many other scholarly contributions on other authors and topics.Footnote ⁶ Lewry's doctoral dissertation, Robert Kilwardby's Writings on the Logica Vetus Studied with regard to their teaching and method (Oxford, Long Vacation, 1978), focused on Kilwardby's lecture course on the Old Logic Footnote ⁷, which included commentaries on Porphyry's Isagoge, Aristotle's Categories and On Interpretation, the anonymous Book of the Six Principles, and Boethius’ Book of Divisions. This set of treatises, which is a record of Kilwardby's teaching at the Faculty of Arts in Paris (from roughly 1237 to 1245), constituted the backbone of university logical education until the works of the New Logic of Aristotle (the Prior and the Posterior Analytics, Topics, and Sophistical Refutations)Footnote ⁸ made their way into the Latin West and the higher education system. (Kilwardby also produced commentaries on all these other works.) Lewry's research on Kilwardby's commentaries had two main benefits: first, it allowed for a better understanding of the system and method of commentary at the early stages of medieval Universities, thereby providing a grasp of their syllabi and teaching practices; and, second, it helped account for the reception of Aristotle and his commentators.

Kilwardby wrote on many topics and influenced his immediate contemporaries. But most of his writings remained in manuscript form until quite recently. Father Lewry was instrumental in making available modern and critical editions of some of those texts. He also investigated questions of authorship, identifying some texts as being by Kilwardby while bringing into question other works attributed to him in medieval catalogues of works (such as the first known catalogue of Dominican works, the so-called Stams Catalogue),Footnote ⁹ or by modern scholars.Footnote ¹⁰ For those unacquainted with medieval sources, it is worth mentioning that medieval manuscripts are often without ascription, which means that authorship must be inferred or concluded on the basis of clues in the text itself – ways of proceedings, certain theories or concepts, expressions, references to other works or events that can be precisely dated, etc. – or external to the work, such as references to that work found in other writings, later ascriptions, information from the codex or volume in which the work is found (namely, other works from what is thought to be the same author). One distinctive feature that Lewry identified in Kilwardby's works that allows for a safe attribution is the formal structure of the Introduction (Proemium), where Kilwardby usually proceeds by identifying the subject matter of the work, the way of proceeding, and the purpose and authorship in terms of Aristotle's four causes: material, formal, final, and efficient (respectively).Footnote ¹¹

An indication of Lewry's impactful research is reflected by the number of works by Kilwarby that were edited to a modern format prior to and after Lewry's pioneering work. Kilwardby's extremely popular introduction to the sciences, the De ortu scientiarum,Footnote ¹² was one of the few that already was available in a critical edition, but since then numerous scholars have worked tirelessly to make the most important works available in the form of modern editions, from his theological commentary on the Sentences of Peter Lombard to his commentaries on the Prior and Posterior Analytics and Ethics.Footnote ¹³ We are now in a better position to understand Kilwardby's thought, but much work remains to be done with respect to both making available critical editions of some remaining texts and with respect to the study of the relation between Kilwardby and his contemporaries. What is clear is that the journey ahead of us may be long, but it is certainly shorter than it would be without Father Lewry's scholarly contributions. His work was a great gift to the study of the early English Dominicans and their role in shaping the development of medieval philosophy and theology.

In what follows, I explore one area of Kilwardby's thought that was first noted by Lewry, chosen because it may be of interest even for non-specialists in medieval philosophy: the question of how the principles of scientific knowledge are acquired. In order to do so, I will briefly connect (rather than offering a full-blown comparison) Kilwardby's answer to this question with those of his two most famous Dominican contemporaries, Albert the Great (ca. 1200–1280) and Thomas Aquinas (1224-1274).Footnote ¹⁴ My aim is to be neither comprehensive nor exhaustive, but to provide a brief introduction to the topic while showing the dynamism and systematicity of medieval thinkers in approaching a theoretical problemFootnote ¹⁵ in a way that Father Lewry would approve: by showing what they have in common, rather than what takes them apart.

II. Knowledge First

The arrival in the Latin West from the mid-twelfth century of a set of new texts of Aristotle on logic, natural philosophy, and ethics had an immense impact in medieval thought. Not only did this contribute to the exponential development of new centers of knowledge, in particular the Universities of Paris and Oxford, but it also contributed to the development of a novel conception of knowledge and science. In the Aristotelian framework, as defined in the Analytics, knowledge is primarily of what cannot be otherwise, meaning that it is about what is necessary rather than what is contingent, of what is universal rather than what is particular. But in order to reach the knowledge of what is universal, one needs to start by knowing the particular things around us. We come into contact with individual things, ‘substances’ in medieval parlance, by means of their accidents, that is to say their properties that we perceive by means of our senses.Footnote ¹⁶ Our perceptual powers collect information about these particular things until the intellect is able to abstract universal concepts from those instantiations. In possession of those universal concepts, we are then able to build demonstrations, that is, deduce conclusions that necessarily follow from those principles and the syllogistic premises.Footnote ¹⁷ A theory of knowledge must therefore explain first, how one comes to knowledge of universals, and second, how universal attributes can be predicated of subjects in a necessary way. In this highly formal and deductive system, the starting points of scientific endeavor are immediately known axioms common to all sciences and a set of high order principles about the specific subject matter of a given science, be that geometry or physics.Footnote ¹⁸ In order to acquire knowledge of the highest sort, one needs to know the basics of demonstration, as Kilwardby clearly points out in the following passage:

But, according to Aquinas and Albert, ‘in order to know the science of demonstration, it is useful to know in what way the first principles are known’Footnote ²⁰: all necessary knowledge is the result of demonstrations, and everything that is demonstrated is dependent upon and certified by those principles.Footnote ²¹ One needs to know first the universals that are the principles of a given science but also the universals that are the middle term of a demonstration, so that in the highest kind of demonstrations, the predicate of the conclusion can be shown to belong to the subject of the conclusion in a necessary and universal way: always and in all cases, and such that it cannot be otherwise.Footnote ²² The first principles at stake here are the definitions that express the natures of things that enter in demonstrations, as subject or attribute. This is the case, even if these thinkers disagree on what the middle term is in the highest sort of demonstration: whereas Aquinas takes the middle term to be the definition of the subject term of the conclusion, both Kilwardby and Albert (the latter probably adopting the former's view) claim that the middle term is the definition of the predicate).Footnote ²³ Be that as it may, an essential part of the scientific enterprise is to identify the nature of the middle term and explain the method by means of which it can be acquired, which in practice is to show how to acquire the knowledge of the universal principles of demonstration. We arrive thus to the central passage of Posterior Analytics, book two, chapter nineteen.

At the beginning of this chapter, Kilwardby reflects of the structure of the whole book of the Posterior Analytics up to this stage and remarks that it offers an overarching argument, which runs from the knowledge of the principles to the knowledge of the conclusion, meaning that only by knowing how to acquire the principles do we come into possession of knowledge that allows us to achieve a necessary and universal conclusion every time.Footnote ²⁴ In a sense, however, the conceptual framework it offers for a theory of human science is the culmination of the whole of logic because both the Categories and the On interpretation are about the meaningful terms, simple and complex (propositions), that enter in the making of demonstrations as determined in the Posterior Analytics and formalized in the Prior Analytics.

With respect to the specific question of how we come to know the first principles, the first option considered in Posterior Analytics II.19 is to take this knowledge to exist in us prior to its being explicitly spelled out, suggesting that we already possess it without being aware that we do, suggesting that it exists in us in a dispositional or habitual way. Doing so is part of Aristotle's (and following him, our medieval interpreters) strategy to deny the implicit Platonism of innate contents. Albert is particularly explicit in identifying the reference to Plato and more precisely to the Meno, observing that this knowledge is not found in us from the outset (insit per naturam) in an inchoate state (latet), which we would come to know explicitly as the result of being exposed to and engaged by things in the world.Footnote ²⁵ Instead, he argues, this knowledge of the first principles is achieved in us by our own cognitive capacities. Kilwardby agrees that this knowledge must come from the exercise of our cognitive capacities, which are prior to their interaction with things in the world, and which are mostly devoid of any cognitive content.Footnote ²⁶ But he clearly identifies a difficulty in the Aristotelian text, which requires both that all knowledge must come from a pre-existing principle and that no knowledge is innate.Footnote ²⁷ He solves this, like Albert and Aquinas will do after him, by taking that pre-existing principle to refer not to content, but to a power or capacity that is capable of coming to know the principles out of which demonstrations can be made. The knowledge itself does not pre-exist, but the power doing the knowing does – pre-existing here meaning being prior to the contact with the things to be known, just like the power of sight is prior in being to actual seeing this or that object.

If this knowledge does not pre-exist in the soul, then it must come from a different source. Kilwardby argues that it cannot originate from intellectual knowledge because the first mode of intellectual knowledge is precisely the knowledge of principles (as showed before, one needs to know the principle prior to knowing the conclusion that follows necessarily).Footnote ²⁸ For us to come to know something, we must be in contact with it, and the capacity to ‘encounter’ things in the world is the perceptual capacity.Footnote ²⁹ To be in contact, however, is not enough, and we must be able to retain something significant from that encounter; the capacity to retain something from that encounter is memory. Now, whereas all animals have a perceptual capacity, some animals have in addition the power of memory, but some lack it. In the case of these imperfect animals, their knowledge is limited to perception of things while present. Kilwardby is keen on stressing the principle that although all animals have sense powers, not all are capable of retaining ‘the sensible species in the absence of the external sensible [thing]’.Footnote ³⁰ Characteristically, Albert elaborates more extensively than the other two on the differences between animals and the powers that they are naturally endowed with. He is also more emphatic than them about the interdependence of these powers, like imagination and the estimative sense, and about the ability of the perceptual capacity of animals to judge incoming sensory information.

There is a general agreement among these commentators that those animals endowed with memory, and thus capable of retaining the information about particular things presented to the senses, are further able to compare and/or collate the information of those particulars. The result of such comparison, collation and even judgment, is the grasping of what is common to them without being particular to any. At a basic level, that comparison is called ‘experience’ (experimentum), and at a more advanced level, when reason or intellect intervenes directly, it results in the discovery of the universal ‘at rest in the soul’ (quiescente in anima).Footnote ³¹ Kilwardby explains that

Even more explicitly than the two others (Albert and Aquinas), Kilwardby makes clear, in the continuation of the text, the different types of general and abstract content different animals are capable of: those endowed with memory but not with reason are capable of a certain content collated from a few instances but that is generalizable to a limited scope of individual things. In contrast, those animals endowed with the powers of memory and reason (memoratiua simul cum ratione) are capable of acquiring a true universal.Footnote ³³ Whereas experience is the kind of knowledge that is true of a certain number of particulars, the universal is one step higher in the abstraction from what is particular and is what can be said or predicated of all the individuals of a certain type: in the example given, that this species of herb (scammony in the original Aristotelian case) cures a fever. The epistemic order is then of a memory being made of sense perceptions, the multiplication of memories resulting in experience (experimentum), and the multiplication of experiences leading to the universal.Footnote ³⁴

The universal is abstracted in the sense that it is separated from the particulars in which it was found instantiated, as their metaphysical formal constituent, but in a strict sense it only exists in the soul. As such, that is as a form of content in the soul, the universal has none of the accidental properties that qualify the particulars in which it was instantiated. Much can be said of the ontological status of that universal as (one) existing in the mind (unum praeter multa) and as existing, particularized (and thus numerically distinct), in the individual things which are said to instantiate it (in multis ut similitudo essentialis in eis):Footnote ³⁵ the whiteness that exists in both this and that shirt. Kilwardby distinguishes between the consideration of the universal according to its essence, as it exists in the mind as one beyond the many; and the universal considered according to its being or existence, as it is in the many (individual things).Footnote ³⁶

The question of the status of universals is a complex one. For my purposes here, it suffices to emphasize that the cause of that universal is not the individual thing in which it exists instantiated and that we perceive; rather, the cause is the mind or reason that takes the sensible species the senses receive and considers it in isolation from the individuating conditions of that particular thing. The key element is the cognitive capacity of reason or intellect that grasps what is essential from what the senses perceive. All three – Kilwardby, Albert, and Aquinas – agree that sensation is of particulars but that it also is of universals, not insofar as the senses apprehend the universal as such, but insofar the senses apprehend that which, upon rational consideration, is grasped as universal: we sense the shirt as white, whereas we grasp that whiteness exists or is instantiated in the shirt (and all shirts of the same type). And even if it is the case that we do perceive individual things as belonging to a certain kind (for example, that we can perceive Callias as a human being), we do so accidentally, and only because reason interacts with our sensory capacities.Footnote ³⁷ Kilwardby elaborates on this idea in an interesting way, which was not taken by either Albert or Aquinas, namely, that the senses are also about what is universal (for example, that we perceive Callias as a human being) because the senses ‘contract’ what the intellect ‘abstracts’. I take this to mean that the senses are about what is universal simply because they perceive the universal form together with – and thus contracted to – the individuating features of that particular thing.Footnote ³⁸

Hopefully it is clear from this brief presentation that for all three thinkers under consideration, it is by means of reason/intellect and by induction from sensation that we apprehend the universals as principles of science,Footnote ³⁹ with which the scientific demonstrations in any given field can be made, and from which the resulting conclusions can be universally and of necessity accepted.Footnote ⁴⁰ That is why Kilwardby remarks that ‘sensation is the door for human cognition and is therefore necessary: if nothing were to remain of the sensible [thing] after sensation, there would be no cognition beyond sensation’.Footnote ⁴¹ Were that the case, all human knowledge would be restricted to what is present and particular, and we would have no ability to know what always is the case (and, thus, no ability to make predictions). Therefore, three of the most important Dominican thinkers of the thirteenth century – Robert Kilwardby, Albert the Great, and Thomas Aquinas – all agree that perception is the necessary starting point for scientific knowledge, even if scientific knowledge properly is the result of a demonstrative process.