8/10/2019 Prior, Rejoinder to Professor Lachs on Omniscience
1/2
DISCUSSION
REJOINDER
TO
PROFESSOR
LACHS ON
OMNISCIENCE
A. N. PRIOR
1.
Knowing
what
does
not
seem
to me to
be
anything
different in
itself
from
knowing
that ;
it is
simply
how
knowing
that
may
appear
to
someone
who does
not
share the
piece
of
knowledge
in
question.
For
example,
my
own
knowing
what
2
and
2
are,
simply
is
my knowing
hat
2
and
2
are
4;
but a
person
who does
not himself know that
2
and
2
are
4,
and
who
therefore cannot
know
that
I
know that
2
and
2
are
4,
might
nevertheless know that I know what 2 and 2 are. (He would know that I
know what
they
are
without
knowing
what
I
know
them to
be.) Sym-
bolically
we
can
easily
do
it
all
in
terms
of
knowing
that
and
quantifiers,
as
follows:
(a)
I
know what
2
and
2
are
=
For
some
x,
I
know
that
2
and
2 are
x.
(b)
He
knows
that
I
know
what
2
and
2
are
=
He knows that for
some
x,
I
know
that
2 and 2
are
x .
(c)
He
knows what
I
know 2 and
2 to be
=
For
some
x,
he
knows
that
I
know that
2 and 2
are x .
2. I don t see
why
God shouldn t knowwhat
doubting
is without himself
experiencing
it.
For to doubt whether
p
is
simply
not
to know
that
p
and
not to
know
that
not
p;
at
least,
for all that Lachs
has
shown
to the con-
trary,
that is
what
doubting
whether
p
is;
and
anyone
can
understand
this
who
has
had
experience
of
knowledge.
3.
I
agree,
however,
that Lachs is on
to
something
here.
Knowing
whether
p,
and even
knowing
what it is to know
whether
p,
do
seem in
some cases to
presuppose
having
experiences,
e.g.
toothaches
and
sinking
feelings
and
dismay,
which
it
is difficult to
imagine
a
divine
being
as
having. I may, for example, mentally advert to a pain which I am experi-
encing,
and
ask
myself,
in
my
private
language,
whether God
knows
that
a
toothache feels to
me
like
this,
and
I
do not see how
God
can
know either
that or
anything
else
directly
involving
a sensation
of this
quality
without
actually having
one.
I
don t
know,
however,
of
any
proof
that
having
such
experiences
would be
incompatible
with
omniscience;
hat
emerges
here is
rather
a
question
as
to whether
omniscience
is
itself
compatible
with other attributes
traditionally
ascribed to
divine
beings.
4.
As
to
time,
Lachs is
right
in
suspecting
that
I
do not
admit
a
single
class
of true
propositions
to which the
same
propositions belong
at all
times. I don t think I can
even
swallow
his
super-class
S.
My
metalogic
at
this
point
has the
same essential
features as
my
logic.
Certainly
we
can
talk
sensibly
not
only
about
the set
of
propositions
which have
been
true and
the set of
those which are
true
now,
but also about the
set of those
which
will
be
true,
and
more
particularly
about,
say,
the
set of those
which will be true
tomorrow.
And
an
omniscient
being
must
know what
propositions
are in
the latter
sets
as
well
as
what
ones
are in
the
former.
This
follows
immedi-
ately
from
proposition
(9)
of
my
article,
together
with the reasonable
365
8/10/2019 Prior, Rejoinder to Professor Lachs on Omniscience
2/2
PHILOSOPHY
assumption
that It will be
the case
that
p
is true
when
and
only
when
the
plain
p
will
be true. But there s
a
point
here that
needs to be
carefully
stated if we are to avoid self-contradiction. The set of propositions that
are true
today
includes a few that
were
not
yesterday
in
the set
then
correctly
labelled
propositions
that will
be true
tomorrow
(because
yesterday
what
would
happen
was
still,
at
some
points,
undecided).
And
it will be true
omorrow
hat the set
of
propositions
then
rue includes
some
which were not the
day
before
(i.e.
the
day
we
now
call
today ) among
those
correctly
labelled
propositions
that will be true tomorrow .
But
we
cannot
say
now which
propositions
these
ones
will
be; indeed,
it isn t
yet
the
case with
respect
to
any specific
proposition
that
it
will
be
in
this
group (if
it
were,
we
wouldbe
landed
with
a
contradiction);
what
is the
case
now
is
just
the
generalpoint
enunciated
in the
last
sentence.
Here,
as
with
knowing
what ,
we must watch where
our
quantifiers go.
What we
have
is that it will be thecasetomorrowhat
certain
specific
propositions
are
of this
odd sort
(true
without
having
been
going-to-be-true
the
day
before);
what
we don t
have
is
that there now are
certain
specific
proposi-
tions which will be tomorrowf
that
sort.
The
theory
of sets of
propositions,
in
short,
must be
handled
with the
same
circumspection
at this
point
as
the
theory
of
everything
else.
ManchesterUniversity.
ON POINTING
E. C. EVANS
ON
page
218
of his article The
Theory
f
Translation
n
the issue for
July
1962,
Mr
Haas
argues against
the
possibility
of
establishing
a
language
by means of rules of reference alone. Pointing is found to be ambiguous
when
not
accompanied
by
other
language:
this
shows that
if
it were the
only
language
it
couldn t
be used to
establish
another.
By
itself it
would
be
hopelessly
ambiguous. (At
a
race,
how
do
we
point
at the
track,
at a
horse,
its
rider,
his
number.
. .
?) (My
dots.)
Now in
fact,
I
maintain,
pointing-gestures
are
usually
quite
unam-
biguous
whether
or
not
they
are
accompanied by
other
language.
Mr
Haas
may
not
believe
this,
but
I
suspect
he acts as
if
he
did,
like
every-
body
else. For
example,
I
drop
my
pocket-book
and
someone
taps
me on
the
shoulder and
points
to
where
it
lies.
Where
is
the
ambiguity?
An indicative movement is not really very like a word-for one thing
it is
already being
used-but
given
that one
thinks
it is
(see
p.
218,
second
paragraph)
the idea that
by
itself
it
must
be
ambiguous
follows
quite
naturally.
One asks oneself what it
means,
and
the answer
comes
to
mind
that it
means,
near
enough,
that
the other
person
should look. It
is then
rather
easy
to
suppose
that the function of
an
indicative
movement
is
always
or
nearly always
to
say
look.So
attendance
at a
spectacle,
such
as
a
horse-race,
presents
itself
as
a
typical
context of
use,
and
searchlight-
366
PHILOSOPHY
assumption
that It will be
the case
that
p
is true
when
and
only
when
the
plain
p
will
be true. But there s
a
point
here that
needs to be
carefully
stated if we are to avoid self-contradiction. The set of propositions that
are true
today
includes a few that
were
not
yesterday
in
the set
then
correctly
labelled
propositions
that will
be true
tomorrow
(because
yesterday
what
would
happen
was
still,
at
some
points,
undecided).
And
it will be true
omorrow
hat the set
of
propositions
then
rue includes
some
which were not the
day
before
(i.e.
the
day
we
now
call
today ) among
those
correctly
labelled
propositions
that will be true tomorrow .
But
we
cannot
say
now which
propositions
these
ones
will
be; indeed,
it isn t
yet
the
case with
respect
to
any specific
proposition
that
it
will
be
in
this
group (if
it
were,
we
wouldbe
landed
with
a
contradiction);
what
is the
case
now
is
just
the
generalpoint
enunciated
in the
last
sentence.
Here,
as
with
knowing
what ,
we must watch where
our
quantifiers go.
What we
have
is that it will be thecasetomorrowhat
certain
specific
propositions
are
of this
odd sort
(true
without
having
been
going-to-be-true
the
day
before);
what
we don t
have
is
that there now are
certain
specific
proposi-
tions which will be tomorrowf
that
sort.
The
theory
of sets of
propositions,
in
short,
must be
handled
with the
same
circumspection
at this
point
as
the
theory
of
everything
else.
ManchesterUniversity.
ON POINTING
E. C. EVANS
ON
page
218
of his article The
Theory
f
Translation
n
the issue for
July
1962,
Mr
Haas
argues against
the
possibility
of
establishing
a
language
by means of rules of reference alone. Pointing is found to be ambiguous
when
not
accompanied
by
other
language:
this
shows that
if
it were the
only
language
it
couldn t
be used to
establish
another.
By
itself it
would
be
hopelessly
ambiguous. (At
a
race,
how
do
we
point
at the
track,
at a
horse,
its
rider,
his
number.
. .
?) (My
dots.)
Now in
fact,
I
maintain,
pointing-gestures
are
usually
quite
unam-
biguous
whether
or
not
they
are
accompanied by
other
language.
Mr
Haas
may
not
believe
this,
but
I
suspect
he acts as
if
he
did,
like
every-
body
else. For
example,
I
drop
my
pocket-book
and
someone
taps
me on
the
shoulder and
points
to
where
it
lies.
Where
is
the
ambiguity?
An indicative movement is not really very like a word-for one thing
it is
already being
used-but
given
that one
thinks
it is
(see
p.
218,
second
paragraph)
the idea that
by
itself
it
must
be
ambiguous
follows
quite
naturally.
One asks oneself what it
means,
and
the answer
comes
to
mind
that it
means,
near
enough,
that
the other
person
should look. It
is then
rather
easy
to
suppose
that the function of
an
indicative
movement
is
always
or
nearly always
to
say
look.So
attendance
at a
spectacle,
such
as
a
horse-race,
presents
itself
as
a
typical
context of
use,
and
searchlight-
366