Medieval Logic and Metaphysics

A Modern Introduction

D.P. Henry

• Publisher: Taylor & Francis
• Year: 2019
• Print ISBN: 9780367182717
• eBook ISBN: 9780429594243
• Edition: 1
• Topic: History
• Subtopic: World History
• Index: History

Originally published in 1972, Medieval Logic and Metaphysics shows how formal logic can be used in the clarification of philosophical problems. An elementary exposition of Le?niewski's Onotology, an important system of contemporary logic, is followed by studies of central philosophical themes such as Negation and Non-being, Essence and Existence, Meaning and Reference, Part and Whole. Philosophers and theologians discussed include St Anselm, St Thomas Aquinas, Abelard, Ockham, Scotus, Hume and Russell.

Part I

INTRODUCTION

§1 MEDIEVAL PHILOSOPHY AND MEDIEVAL LOGIC

There is a clear and salient contrast between the state of the history of medieval philosophy and that of the history of medieval logic. The first is an already-venerable discipline, and has customarily been the province of thinkers who themselves are part of the post-medieval phase of philosophising, literary in mode, and remote in style and content from the logically-structured and economically-expressed output of the medievals. The second, the history of medieval logic, is a comparatively new study, which according to the avowals of its own practitioners is still in an elementary and primitive state. There are, however, at least a couple of reasons why the further development of the history of medieval logic would appear to be of the very highest interest. In the first place, there is no doubt that the concerns of medieval logicians and philosophers were often closer to those of contemporary philosophers than to those of philosophers who lived in the intervening centuries, given the current concern with problems of language and meaning. It is already clear that an intelligible conversation between medieval logicians and modern philosophers could be quite profitable. In the second place, given the already-mentioned logical complexion of medieval philosophising in general, a result of such a conversation could be a fuller understanding of that philosophising, particularly in its more metaphysical stretches. Such a result would scarcely be surprising in view of the literary and non-logical cast of mind of most of those who have hitherto taken upon themselves the study of the history of medieval thought. Another concomitant result would be a more unified perspective of medieval thought as a whole, carrying with it the possibility of settled and conclusive verdicts on the nature and content of that thought in some of its aspects.

§2 MEDIEVAL LOGIC AND MODERN LOGIC

At this point the question may well be raised as to the extent to which contemporary studies of medieval logic are capable of fulfilling the sort of promise outlined above. Medieval logic was a philosophical logic, closely geared to philosophical themes. What then could a purely formalist logic, interested purely in combinations of uninterpreted notation, have in common with medieval logic? Again, assuming that this first difficulty may be obviated by the use of a non-formalist type of modern logic, the fact still remains that both in logic and metaphysics the medievals used a highly systematised Latin, extremely rich and daring in its proliferation of forms of speech belonging to recondite semantical categories. How then is it possible for a philosophical formal logic of the current sort in this respect to rival and exceed (as it must) the medieval artificialised language? Finally, the medievals were blithely uninhibited by any of the dark and knotty controversies which have arisen as a result of our contemporary entanglement of the notion of existence with the device central to modern formal logic, namely the device of quantification (cf. II §2). How then can modern logic, caught as it is in this entanglement, recapture the untrammelled approach to existence enjoyed by its medieval predecessors?

So far, only questions of broad principle have been raised, but it is not difficult to raise doubts at the level of the details of down-to-earth analysis of medieval theories. Already in BML a certain uneasiness had been voiced (BML 28–31, BML 44; cf. III §3). These doubts were made more explicit in MMC, and one way of spelling out the nature of one of them arises from the different ways in which a propositional form of the type in which the medievals were interested can be analysed. Let it be premised that a name and a predicate or verb, i.e. a form which when completed by a (proper) name constitutes a proposition (assertive sentence), are diverse parts of speech. Now as is made clear in RI 162, for instance, it is considered by some modern logicians that the correct analysis of a sentence such as ‘All men are mortal’ would run ‘For no matter what x, if x is a man, then x is mortal’, wherein ‘x’ is a variable for proper names. But now it is evident that the ‘men’ and ‘mortal’ parts of the original sentence, parts which would be considered as names (taking ‘name’ to comprise adjectives as well as common and proper nouns), have the predicates ‘… is a man’ and ‘… is mortal’ as their counterparts in the modern analysis.

However, the medievals, although aware of this possibility of the ‘predicatisation’ of names (BML 28, 30), would still wish to view ‘man’ and ‘mortal’ as names and not predicates, or at any rate would not ‘construe both terms of a general categorical proposition as predicate terms’ (MMC 448). Now in some other segments of the more familiar modern logic it is still possible to take ‘man’ and ‘mortal’ to be names, but they then turn out to be the proper names of entities called ‘classes’, i.e. ‘All men are mortal’ is construed as ‘The whole of the class of men is included in the class of mortal beings’; this is plainly alien to the point of the original assertion, which many of the medievals would take to be about men and mortal beings, and not about the interrelationships of two further class-entities. In Moody’s terms, ‘the medieval logician did not construe the terms of such propositions as singular names of classes, but as general names of individuals’ (MMC 449).

At the present juncture, therefore, in the light of these remarks and others which will be cited in III §1, it would appear that explanations in ordinary language, with only rare and occasional help from the language of formal logic in comparatively uninteresting contexts, is the most that can be expected of the history of medieval logic. Under these circumstances the promise of the sort of definitive conclusions which formal logical analysis would provide concerning the sense and validity of medieval logical and philosophical theses seems to be impossible of fulfilment.

Fortunately it happens that there exists a system of modern formal logic, unfamiliar to many logicians and philosophers, and sometimes misunderstood by others, which allows the investigator to overcome all of the difficulties stated above, and from the standpoint of which many of the further difficulties which may still be raised can be satisfactorily resolved. This logic is that of the Polish logician S. Leśniewski (1886–1939), a partial account of which may be found in Part II below. This logic is anti-formalist, in that its theorems are interpreted truths, and not mere syntactically-permissible combinations of uninterpreted marks (cf. II §0.00). It has the capacity for the introduction of indefinitely many new parts of speech (semantical categories) and hence can adapt itself to the required degree of exactitude for the purpose of analysing medieval logic, as Part III will demonstrate. It employs an interpretation of the quantifiers which allows dissociation of the latter from its usually necessary entanglement with the notion of existence (II §2.23, II §2.25), and so is in a position to come to more exact terms with medieval discourse on this topic.

It follows that the purpose of the present work is three-fold. After the preliminary consideration of the field which is contained in this introduction, a practical account of one of the central theories of Leśniewski, namely his Ontology, will be presented in Part II. Thus armed, we will be in a position to expose in detail in Part III some examples of the way in which Ontology may be used in the analysis of medieval themes.

Now this may all sound to be a formidable undertaking for those readers who are no logicians, and they may feel tempted to remain at the level of analyses and explanations conducted in everyday language, with perhaps a few elementary terms or scraps of notation from current logic or linguistics thrown in. Indeed, there may be some who in spite of their own logical competence are as yet unconvinced of the value of making a text intelligible in the light of a fully systematised language, and who would protest that if intelligibility cannot be offered by explanation in terms of comparatively ordinary language, then so much the worse for the medievals who insist on being unintelligible in this way. To such objection three types of reply are possible. First, efforts have been made in Part II to give an explanation of Leśniewski’s Ontology, with which we are to be mainly concerned, of so elementary a nature as to be easily grasped by all who have only the slightest acquaintance with the logic of propositions and the notion of quantification. Secondly, as has already been contended above, the highly systematised technical logical Latin of the medievals involved the introduction of new parts of speech which stand outside the elucidatory capacities of ordinary language. Thirdly, even if ordinary language is itself artificialised somewhat in the medieval sort of style, there are limits to its intelligibility unless the analysis is carried forward into a fully systematic language such as that of Ontology. Partly in support of this contention an effort will now be made to give a preliminary appreciation and survey of the nature of themes which are to be touched upon in Part III. In the course of this effort ordinary language will be strained to the uttermost in order to come to terms with the way in which the scholastics modified such language for technical purposes. Even this straining will, in the end, be found wanting; this will convey concretely the necessity of going yet further, to the fully artificial language outlined in Part II.

§3 PRELIMINARY SURVEY

It is to the ill-fated Boethius, who died by the order of a barbarian emperor in the year A.D. 524, that our segment of the history of logic chiefly owes its origin. His grandiose plan had been to translate into Latin and elucidate the works of the ancient Greek philosophers. In point of fact he accomplished only the translation of Aristotle’s logical works, along with commentaries on some of them, as well as some monographs based on Aristotelian and Stoic sources. Only some of these were available to early medieval logicians, such as St Anselm (1033–1109), the ‘father of Scholasticism’; thus he would know Boethius’ version of Aristotle’s Categoriae and De Interpretationen along with Boethian commentaries on these and on the Isagoge of the neo-Platonist Porphyry; Boethius’ own works on the categorical and hypothetical syllogism were also known at this time. Only later, however, did Aristotle’s Analytica (prior and posterior), Topica, and De Sophisticis Elenchis afford meat for the busy minds of medieval logicians (cf. DLM, KDL, BH).

Nevertheless, the judgement of the seventeenth-century English philosopher John Locke could already have St Anselm as one of its targets. For when Locke accuses the schoolmen of having ‘covered their ignorance with a curious and inexplicable web of perplexed words’, he touches upon one of the essential and generally-admitted characteristics of much medieval philosophy and logic of which Anselm was already acutely conscious, namely its progressive systematisation of the Latin in which it is written. At times this systematisation goes over the boundaries of sense into what is, from the point of view of ordinary, pre-technical discourse, nonsense (cf. III §2).

In order to achieve a concrete appreciation of what is involved here, as well as a preview of some of the problems to be investigated in Part I...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Original Title Page
• Original Copyright Page
• Table of Contents
• Preface
• References and Abbreviations
• Part I: Introduction
• Part II: Ontology
• Part III: Applications
• Index