The Genealogy of Disjunction

357 Pages·1994·21.24 MB·English

by  R. E. Jennings

The Genealogy of Disjunction
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The Genealogy
of Disjunction
R. E. JENNINGS
New York Oxford
OXFORD UNIVERSITY PRESS
1994
Oxford University Press
Oxford New York
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Copyright © 1994 by R. E. Jennings
Published by Oxford University Press, Inc.,
200 Madison Avenue, New York, New York 10016
Oxford is a registered trademark of Oxford University Press
All rights reserved. No part of this publication may be reproduced,
stored in a retrieval system, or transmitted, in any form or by any means,
electronic, mechanical, photocopying, recording, or otherwise,
without the prior permission of Oxford University Press
Library of Congress Cataloging-in-Publication Data
Jennings, R. E. (Raymond Earl) The genealogy of disjunction /
R. E. Jennings,
p. cm.
Includes bibliographical references and index.
ISBN 0-19-507524-2
1. Disjunction (Logic) 2. Or (The English word) I. Title.
BC199.D56J46 1994
160—dc20 93-11592
987654321
Printed in the United States of America
on acid-free paper
For Hugues Leblanc
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Preface
Gilbert Ryle has remarked that the difference between philosophers and formal
logicians is akin to the distinction between explorers of the moors and operators
of tramways. The sensitive research logician may puzzle whether to accept the
wayfarer's innocent admiration and wave back or to say something clever to
disarm the social irony. For he is as likely as not to think of himself more on a
footing with designers of tramways than with their operators, more on a social
level with consultant to the corporation than with liveried employee. But the
metaphor is more fundamentally misleading, and not intended as a slight. Much
of the product of logical research has little anymore to do with secure inferential
conveyance. Even the little light that might once have fallen fleetingly but
usefully upon a ditch or a dead sheep shifts remorselessly ever toward the
infrared. The vehicle is anymore only a logically possible tram.
Ryle's imagery is, however, vividly correct in one particular: logic in its usual
presentation is a recent invention, in fact, not much older than the tram. And,
even if neglectfully of some of the newer track, he rightfully regards logic as,
like the tram, restricted in the manner of its service. But again, as it places the
logician too close to the ground, the imagery locates his philosopher wrongly in
a wild, not urban landscape. The philosopher's problem is not one of finding
unfamiliar things to prod. His subject matter crowds him round. If it is
perplexing, it is so not because it is alien, but because it is human and so
familiar. The difficulty is that, at the level at which we want understanding, we
do not understand the linguistic things that we do or how we do them. If a
geographical image is sought, let it be the image of a cityscape filled with long
evolved, albeit human contrivances, so far removed from their original materials
and uses that, though everyday they serve our purposes, we can no longer fit
their form to their function.
This book is an attempt to say how some of our logical vocabulary works in
discourse. Its central subject matter is the word 'or', but the approach that it
finally advocates it advocates for the study of other such vocabulary as well.
'Or' presents some curious and easily illustrated puzzles, that, possibly because
they have not been recognized for what they are, have not been the source of
entrenched philosophical doctrine. In this respect, 'or', unlike 'if, really is, to
revert to something like Ryle's metaphor, virgin territory. There is yet time to
save it from development, and from what seems to me to have been, in the case
of 'if, the monopolistic application of wrong methods.
My own perplexities about 'or' were sown in 1964 by a reading of von
Wright's Logic of Preference and provided some of the subject matter for two
theses, an M.A. thesis at Queen's University written under the supervision of the
late Jon Wheatley and a Ph.D. thesis at the University of London under the su-
Preface viii
pervision of Bernard Williams. In the second, I proposed essentially the account
of the puzzling conjunctive uses of 'or' that is further elaborated here, as well as
the derivative account of the 'any/every' distinction that is the core of the one
contained in this essay. But the punctuational explanation, as far as it had got,
was unsatisfying inasmuch as it seemed unconnected with what I took to be the
usual sentential uses that I simply assumed to be disjunctive. And there were
other things to do. Several developments persuaded me to take it all up once
again. The first was the large literature on 'if', a subject being called the logic of
conditionals, that had never received the kind of simple-hearted scrutiny that had
revealed so much that was perplexing about 'or'. The nearest to an analogous
literature on 'or', as it seemed from the almost ostentatious isolation of
academic philosophy, was pullulating within the confines of deontic logic under
the heading of 'free choice permission'. It may be that no one had noticed essen-
tially the same and odder features in the behaviour of 'or' throughout its uses in
English, else there might have come into existence something calling itself the
logic of disjunctions. News of the existence of a Counter-Earth in which lin-
guists, with a much broader landscape in view, had been puzzling over the very
problems that I had so long ago set aside reached me late in my application of
CPR to older work. As might be expected, different starting points had yielded
different emphases, though there had as well been some points of contact. In
addition, the aims of the linguists were at an angle oblique to the aim of this
essay: to try to say how we come to have a notion of logical disjunction. Much
of the linguists' thinking about 'or', it seems, has had the truth-tabular V as one
of its light sources, so that the ideas of disjunction and set-theoretic union
contribute perceptibly to its cast. So while I have tried to acknowledge points of
contact and parallel developments, it has seemed best not to seem to be offering
this essay as a response to current linguistic approaches, but to address myself to
the philosophical problem I have set. Linguists by now are surely justified in
assuming title to this portion of the moor and may, come to that, have their own
ideas about which is Earth and which Counter-Earth. So I beg their indulgence
as a former denizen if I seem to wander their marches in a stupor and to see the
landscape as it was. Two recent developments within linguistics have seemed to
confirm this course. The first is Victor Dudman's investigation of if... then . . .
sentences which has brought us back from rhapsodic mythologizing about
conditionals to something like simple systematic observation of if-clauses as
adverbial modifications. The second is Laurence Horn's study of negation,
which, in questioning the centrality of sentence-negation, provides a confirming
datum to the view I shall put forward. Within this family of studies, as I hope to
have demonstrated, 'or' deserves a volume to itself. If this work forestalls a
wholly unwarranted development of logics of funny disjunctions, it will have
served one of the purposes for its existence.
The second reason lies in the growing abundance of logic textbooks retailing
wholly gratuitous (and with a moment's reflection, perfectly apparent)
falsehoods about the relationship between the disjunction of prepositional logic
and the 'or' of English (and some of its counterparts in Latin), and that to no
very important expository end. It seemed worthwhile to register the errors in an
ix Preface
essay large enough to discuss a sufficiency of convincing examples and also
begin a more plausible alternative account.
The third reason arises out of the second. As it seems from its fringe,
emerging research in computer discourse generation is ill served by the
prejudice, which the glib myth making of the logic texts tends to instil, that the
central uses of 'or' and other 'logical' vocabulary of natural language are wholly
to be accounted for by a truth conditional theory along the lines of formal
semantics. To the extent that such research programmes are aided by possession
of the right general principles, it seems worthwhile to try to pick out the
regularities that a proper set of principles would codify and above all, to try to
get right the vocabulary of the observation language. If an instructively
oversimple slogan were to emerge from my efforts and be offered as amicular
advice to discourse generation researchers, along the lines of the earlier 'Don't
ask for the meaning; ask for the use', it would be 'Mainly we emit sounds'. In
trying to understand, in a usefully general way, the sounds that we make, the
pragmatic notions of discourse status and discourse adverbiality, however im-
perfectly formulated here, are likely to be more central than the notion of truth
conditions, which after all applies only to theoretical entities of dubious origins
whose relationship even to the narrow range of indicative speech that it is taken
to explain is as tenuous as it is mysterious.
In the end, whether it has been worthwhile to write so long a book about so
short a word is for the reader, not the writer, to say. But the writer, who best
knows the reason for the work, is best placed to offer negative criteria of
adequacy. One would be this: if the essay does not suggest strongly to the reader
that a large part of our so-called logical vocabulary comes to its present uses
from metalinguistic applications of the language of physical relationship, and
that in much of its ordinary use it retains the kind of adverbiality that is claimed
here for 'or', then I will have missed my mark. Second, if it does not
demonstrate convincingly the worth of simply trying to sort out how the same
logical vocabulary works in discourse, then it will have been insufficient means
to one of its ends. No part of its task is to attempt a formal representation within
logical theory, rather the reverse.
I am indebted to the late Jon Wheatley, who encouraged me to enter
Philosophy and who supervised the earlier thesis, to Bernard Williams, who
supervised the second, and the late Arthur Prior who examined it, to Risto
Hilpinen, who encouraged me to take the project up again, or at the very least to
publish the earlier work as an historical curiosity. In the course of writing and
presenting to various forums what eventually became the present document,
many colleagues have offered invaluable criticisms and advice and asked useful
questions. Among them I should mention (in more or less chronological order)
Rolf George, Max Cresswell, Peter Schotch, Jeff Pelletier, Johan van Benthem,
Souren Teghrarian, Robert O'Toole, Hugues Leblanc, Michael Dowad, Robin
Taylor, Charles Travis, Dorothy Edgington, Martin Hahn, Norman Swartz, and
Mary Shaw. I especially wish to thank an anonymous Oxford University Press
referee for useful truths about the state of the academic solar system and many
detailed bibliographical and substantial suggestions.