The Nachlass of A.N. Prior
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Department of Information Studies - University of Copenhagen
and
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Existence

By Arthur N. Prior on NA/NA/1959

This text has been transcribed by Martin Prior and Peter Øhrstrøm

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Existence
1

A.N. Prior


I have decided not

to argue here about whether existence is a predicate or not.
Of course it is. But what
is the
relationship to

other predicates?

Does ‘X is Y’ always entail ‘X is’?

Aristotle
on this point

–

[gives]
2
views
, in
Cat
,
and in
De Int.

and
Top
.

Obviously 2 sorts of predicate
, one
s
that imply

existence and one
s that do
n’t.

Coming

to Ru
s
sell:
[he]
distinguishes

not
only 2 sort
s

of predicate
, b
ut 2 sort
s

of
subject
, I
mean 2 sorts of
simpler subject

–

logical proper names
,
a
nd
d
efinite descriptions. Re definite descriptions
:
s
imple

predicates
imply existence, complex ones are ambiguous
.

{2}

‘The X is a
{
possible/alleged/former/non
}

Y’ [is] differentiable from ‘It is
{
possible/alleged/now a
thing of the past/not [the case]
}

that
the
X is a Y
.
’

With logical proper names the case is different. These
mean

by
identifying
; if they fail to identify an object,
no sentence. So ‘This exists’ is a true sentence, if it is a sentence at all and ‘This doesn’t exist’ a false
sentence if i
t is a sentence at all
. (That’s not how Russell puts it, but Moore; Russell says ‘This exists’ is
meaningless, but I think Moore here has a better proof of what Russell’s position implies than Russell
himself has). And there’s no difference between ‘
This

is a {…} Y’ and ‘It is
{…} that
this

is a Y’.

If
sentences at all, and
this

has some reference, they have some truth
-
value.

Other complications here, though. Moore’s reason
s

for saying ‘This exists’
and ‘This doesn’t exist’

are
meaningful. ‘This might not have {3}

existed’ is sometime
s tr
ue, and sometimes shown as

facts
2
.

But how
does it?

It is possible that this doesn’t exist
.

i.e.

the non
-
existence of this is a possible state of affairs. But is it?
-

Cf. ‘Once this didn’t exist’, which you
might
equate
3

with.

It was the case that

(this doesn’t exist)

(‘This doesn’t exist’ was once true)
. But
when

was it? Does this mean

that variati
on

exist
s
, exists necessarily and permanently?

Similar to a trick of Ramsey’s. Ramsey held that assertions about the
number

of objects in the universe are
all eit
her tautologies
4

or contradictions. Proof:
-

Propositions about identity and

otherwise are all necessary
propositions. So this, say, is necessary:
-


{
a


b, a


c, b


c
}

and this necessarily implies ‘There are at least 3 individuals’; and what is necessar
ily implied by a necessary
truth

is a necessary
truth;


it is a necessary
t
ruth that there are at least 3 individuals
.
5




1

This MS is kept in the Prior collection at the Bodleian Library, Oxford. It has been edited by Martin Prior and Peter
Øhrstrøm.

It has not dated, but it is written on note paper of the Department of Philosophy, University of Manchester,
and only shows Pro
fessor Dorothy Emmett as head of department, suggesting that the notes were written soon after
A.N. Prior came to Manchester in 1959. It seems that it forms notes for a lecture.

2

The text is uncertain. The subsequent question “But how does it?” presumably refers to the uncertain text.

3

The text is uncertain.

4

The text might read ’tautologous’.

My own solution is to distinguish between ‘necessarily’ and ‘not possibly not’; and in time, between ‘has
always been true’ and ‘has never been false’.

{4}

(Deal

[with]

in detail)

If we have no

logical proper names, these complications can be dropped. But then we go back to the
other

complications.


The X is a
{
non/alleged/possible/former
}

Y
.

must be distinguished from


It is
{
not the case/alleged/possible/over
}

that the X is a Y
.

Moreover, [we
] can’t always define a short form as the long form + ‘The X exists’,

e.g.

(a) The X is a possible
-
non
-
exister
.


(might not have existed)



(b) The X does exist, but it might have been that ‘the X doesn’t exist’.


Not

more

∵

this last is nonsense but

∵

i
t

doesn’t mean the same thing
. ‘The X doesn’t exist’

means ‘there is
no unique X’ and this does
n’t
… etc
6
.
And existence
isn’t the only case where there are these differenc
es,
though it’s a striking case.

Walther’s house might have had wings
.




Walther’s
house exists (i.e. Walther has a house) and it might have been that Walther’s house has
wings
.


{5}

Summing up, admitting existence as a predicate complicates logic, one way or another, but the complications
aren’t unmanageable, and least some of them
woul
d
be forced on us even if we didn’t

list

existence as a
predicate.







5

Prior is using


for ‘therefore’ and
∵

for
‘
because
’
.
This usage is common in both
New Zealand and Britain,
e
specially the former in geometric proofs
.

6

The text is uncertain, but looks like ’&c’, where the first symbol is consistent with Prior’s usual representation of the
ampersand.

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18-12-2018 13:48:41 (GMT+1)