Thought

Burley’s contribution to philosophy is most visible in two disciplines: logic and natural philosophy. He is not

Henrik Lagerlund (ed.), Encyclopedia of Medieval Philosophy, DOI 10.1007/978-1-4020-9729-4, © Springer Science+Business Media B. V., 2011

A deliberate innovator. He tries to give a precise and penetrating (planus et perspicuus, hence his nickname) explanation of the teaching of Aristotle and other authorities, which would be in agreement with the common opinion of scholars (communis opinio doctorum). It is seldom that he opposes the prevalent views or proposes a new solution. Still, in both fields he is able to leave a visible mark of his talent. In logic, his De suppositionibus, giving an overview of the theory of supposition, helped to revive interest in it not only in William of Ockham; his De obligationibus, De exclusivis, De exceptivis, and other treatises similarly set standards for respective parts of logical theory. His main logical work, De puritate artis logicae, was intended to be a comprehensive study of the whole discipline: Burley did not complete his project in the original version, now known as Tractatus brevior, but returned to it later and revised it in Tractatus longior. The two versions of De puritate contain a thorough though not uniform presentation of types of logical argumentation; in Tractatus brevior he divides them into enthymematic consequences, conditional syllogistic consequences, and hypothetical unconditional consequences; in Tractatus longior, written with a clear polemical intention against Ockham, he refined his original division of consequences into absolute and as-of-now ones, further dividing the former category into natural and accidental ones (the criterion being whether the antecedent includes the consequent), and introducing three other divisions.

As a realist, he believes that logic is nothing but an analysis of general structures of reality. Aristotle’s categories show an order that things bear in themselves (first intentions) and that is only secondarily reflected by our ways of speaking about things (second intentions), therefore logic and ontology are inseparable. The opposition to Ockham’s nominalism is best visible in his views on supposition: for Burley, the word ‘‘man’’ in the proposition ‘‘Man is the noblest creature’’ is in the simple supposition because it signifies something, i. e., a species, for Ockham, it is not because it signifies a mental intention rather than a true thing. Burley’s realism does not go as far as Scotus’; however, he agrees with the Subtle Doctor that both common nature and individual difference really exist, but he denies that they differ only formally. Burley tries to avoid the subtleties of formalitates and claims that the differences between universals are real. Moreover, common nature is not contracted by the individual difference, as was the opinion of Scotus, but remains in an individual in its totality. This assumption allows Burley to analyze the divisions of a universal, looking for something general in various items of minor generality. Though he upholds the real difference between universals, he denies it - contrary to Giles of Orleans - between essence and existence.

In natural philosophy, Burley’s interests were truly focused on the problems of duration and change. He analyzed it on various levels of abstraction, starting from particular classes of things and actions observed in the world. Some of his opinions were modified in successive works, of which the most important are the three versions of his Physics commentary, the commentary on De generatione et corruptione, and three Parisian treatises on change. The constant part of Burley’s views on elementary and organic change can be summarized as follows. Prime matter, devoid of definite dimensions, is first informed by primary qualities, which - working in pairs - constitute the forms of first bodies, i. e., the elements. Heat is the first among equals in primary qualities. Its activity causes both generation and corruption; it is necessary for life but brings about death too. These various forms of action are related to various types of heat: celestial, elementary, and animal. The three types do not differ from one another in their natures, on the contrary, they share the same nature, and the observable differences between them are attributed to intensity in action, which in turn is dependent on the source of heat. Elements constituted by heat and the remaining three primary qualities serve as material for all bodies of sublunary world in such a way that every body is a mixture of all elements, which are virtually present in it (an idea borrowed from Thomas Aquinas), and their qualities concur to produce a mixed quality, characteristic for a particular body.

The bodies of inanimate beings, such as minerals, are constituted from elements under the influence of celestial heat. In animate beings, the process is more complex, for it requires concurrence of three parties: the form of a generated being, say an animal, comes in semen from the male parent, matter is provided by the female parent, and solar heat is a necessary condition for creation of a new life. Semen is a form that exists only during the process of generation passing the nature to the newly formed being; in the same vein, an embryo remains a quasi part of a mother until a vegetative soul is formed in it.

Animate beings need food both for preservation of life and growth. In the process of nutrition, the form of food is destroyed in such a way that animal heat digests the humidity of the food, which brings about the destruction of its substantial form. The matter is then immediately informed by the substantial form of the animal. Subsequent physiological processes are dependent on the quantity of digested food. If it is sufficient, an animal preserves its life in its perfection or, if it has not reached its perfection yet, it grows. If it is insufficient, animal’s heat starts

Digesting its own humidity, which causes shrinking of the body and may bring about death. If it is superfluous, an animal not only preserves its form (regardless of the stage of its development) but puts on weight: this is a process in which the excess food is converted into new parts of the body. It is different from growth in the sense that no new parts are produced. Both putting up weight and growth produce a secondary change in the extension of a body, which occupies larger space as a result of each. Unlike the former two processes, the change in extension is continuous, for space is infinitely divisible but bodies are composed of minima naturalia, since flesh or bones cannot be divided infinitely without losing their properties. Apart from extension (covering a larger space), qualities of a body may also possess their intension (greater or smaller degree in which the quality exists).

It is to the problem of intension and remission of forms that Burley devoted most time and attention in his physical works, presenting several complementary solutions. He is best known for a “succession of forms’’ theory, first applied by Godfrey of Fontaines to explain augmentation and diminution. In his early commentaries on the De generatione et corruptione and Physics, Burley saw a qualitative change as a process occurring between specifically contrary forms within the same genus. He noticed that the process can be broken down into infinite individual instantaneous stages, in each of which a quality has a new form of greater or smaller intensity. In De primo et ultimo instanti, he presented an explanation of differences between two modes of understanding qualities undergoing change of intensity: one, seen as a process, and another, seen as an instant. The fullest and most original exposition of Burley’s views on the problem of change can be found in the Tractatus primus. He claims there that also the termini of qualitative change belong to the same species (so, effectively, a qualitative change is between a form and a lack thereof). This allows him to use effectively the concept of latitude of forms to explain the process. The criticism drawn by his original theory made Burley revisit the issue of qualitative change several more times. In his Tractatus secundus and, later, in De formis, he gradually gave up some parts of his solution, and finally, in his Bolognese quodlibet, accepted a Scotist view on the issue, which saw intension or remission as addition or subtraction of individual degrees of a form, merged into it.

In his theory of local motion, Burley accepts the prevalent Aristotelian division into ‘‘permanent beings’’ and ‘‘successive beings,’’ the former being objects, the latter, motions. Permanent beings have their first instants, but not last ones, successive beings have neither. This distinction allows Burley and other realists to analyze motion in separation from objects in motion. For Ockham, who recognized only substances and qualities as things, motion was not separable from its object and thus was understood only as forma fluens, disregarding the other aspect of motion distinguished by Avicenna, fluxus formae, i. e., flux of form, belonging to the category of relation. For Burley both aspects of motion had to be taken into account in order to give an adequate description of it.

Practical philosophy attracted Burley’s interest relatively late and his contributions to that field are the smallest despite the size of his works devoted to it. Although it was not uncommon for him to follow some authority in his works in logic and - more often - in natural philosophy (for instance, Averroes), the commentaries on Nicomachean Ethics and Politics exhibit extraordinary dependence on the commentaries by Thomas Aquinas and Peter of Auvergne respectively. Burley does not add to their opinions much beside references to English cultural context.

Burley’s intellectual activity brought him renown of his contemporary and later philosophers. A good measure of this respect is the number of works mistakenly attributed to him, of which two, Auctoritates Aristotelis and De vitis et moribus philosophorum, were very popular until the end of the Middle Ages. Problems with attribution of some known works and possibility of discovering or identifying some new ones make the list of his works still open for change.

See also: > Giles of Rome > Godfrey of Fontaines > Ibn Rushd, Muhammad ibn Ahmad al-Hafid (Averroes) > Ibn Sina, Abti ‘All (Avicenna) > John Duns Scotus > Logic

>  Natural Philosophy > Realism > Supposition Theory

>  Thomas Aquinas > William of Ockham