Alfred J. Ayer - (1946) Language, Truth and Logic.pdf

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LANGUAGE,
TRUTH AND LOGIC
by
ALFRED JULES AYER
Grote Professor of the Philosophy of
Mind and Logic at University College, London
DOVER PUBLICATIONS, INC.
NEW YORK
DOVER PUBLICATIONS, INC.
To R. A.
Printed in the U.S. A.
INTRODUCTION
In rue ren vEARs that have passed since Language, Truth
and Logic was first published, I have come to see that the
questions with which it deals are not in all respects so simple as”
it makes them appear; but I still believe that the point of view
which it expresses is substantially correct. Being in every sense
a young man’s book, it was written with more passion than most
philosophers allow themselves to show, at any rate in their
published work, and while this probably helped to secure it
a larger audience than it might have had otherwise, I think now
that much of its argument would have been more persuasive if
it had not been presented in so harsh a form. It would, however,
be very difficult for me to alter the tone of the book without
extensively re-writing it, and the fact that, for reasons not wholly
dependent upon its merits, it has achieved something of the
status of a text-book is, I hope, a sufficient justification for re-
printing it as it stands. At the same time, there are a numberof
points that seem to me to call for some further explanation, and
I shall accordingly devote the remainderof this new introduc-
tion to commentingbriefly upon them.
THE
PRINCIPLE
OF
VERIFICATION
The principle of verification is supposed to furnish a criterion
by which it can be determined whether or not a sentence is
literally meaningful. A simple way to formulate it would be to
say that a sentence hadliteral meaning if and only if the propo-
sition it expressed was either analytic or empirically verifiable.
To this, however, it might be objected that unless a sentence was
literally meaningful it would not express a proposition;1 for it
is commonly assumed that every proposition is either true or
false, and to say that a sentence expressed what waseither true
or false would entail saying that it was literally meaningful.
Accordingly, if the principle of verification were formulated in
1'Vide M. Lazerowitz, “The Principle of Verifiability,” Mind, 1937,
pp. 372-8.
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this way, it might be argued not only that it was incomplete as
a criterion of meaning, since it would not cover the case of
sentences which did not express any propositionsat all, but also
that it was otiose, on the ground that the question which it was
designed to answer must already have been answered before the
principle could be applied. It will be seen that when I introduce
the principle in this book I try to avoid this difficulty by speaking
of “putative propositions” and of the proposition which a sent-
ence “purports to express’; but this device is not satisfactory.
For, in the first place, the use of words like ‘“‘putative” and
“purports” seems to bring in psychological considerations into
which I do not wish to enter, and secondly, in the case where the
“putative proposition” is neither analytic nor empirically verifi-
able, there would, according to this way of speaking, appear to
be nothing that the sentence in question could properly be said
to express. But if a sentence expresses nothing there seems to be
a contradiction in saying that what it expresses is empirically
unverifiable; for even if the sentence is adjudged on this ground
to be meaningless, the reference to ‘‘what it expresses” appears
still to imply that something is expressed.
This is, however, no more than a terminological difficulty,
and there are various ways in which it might be met. One of
them would be to makethecriterion of verifiability apply directly
to sentences, and so eliminate the reference to propositions alto-
gether. This would, indeed, run counter to ordinary usage, since
one would not normally say of a sentence, as opposed to a propo-
sition, that it was capable of being verified, or, for that matter,
that it was either true or false; but it might be argued that such
a departure from ordinary usage was justified, if it could be
shown to have some practical advantage. The fact is, however,
that the practical advantage seemsto lie on the otherside. For
while it is true.that the use of the word “‘proposition’’ does not
enable us to say anything that we could not, in principle, say
without it, it does fulfil an important function; for it makes it
possible to express whatis valid not merely for a particular sent-
ence s but for any sentence to which s is logically equivalent.
‘Thus, if I assert, for example, that the proposition p is entailed
by the proposition q I am indeed claiming implicitly that the
English sentence s which expresses f can be validly derived
from the English sentence r which expresses g, but this is not
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