
Truth
93
It
must
be
acknowledged, parenthetically, that adding
a
temporal index
to
the
copula
in
this
way
leads
to
complications
in
some
of the
propositional
transformations
that Leibniz proposes. Consider,
for
example,
his
treatment
of
"Peter
is
denying,"
an
existential
proposition
that
he
tells
us is
equivalent
to
"Peter
denying
is an
existent." Clearly,
if
"Peter
is
denying" means "Peter
is
now
denying," then
"Peter
denying
is an
existent" must mean
"Peter
now
denying
is an
existent," rather than "Peter denying
is now
existent." For,
according
to
Leibniz, Peter, like every other monad, exists
at all
times
if he
exists
at
all.
It
seems clear, therefore, that when
'A
is,
B' is
transformed into
'AB
is an
existent',
the
time index
t
must attach
to the
compound
'AB';
'AB'
must
be the
concept resulting
from
combining
B
with
the t
-stage
of
A.
Thus,
when
an
individual concept
is one of the
components,
the
composition
of
concepts
has to be a
different
sort
of
operation
from
what
it is
otherwise.
Further,
if
'A
is,
B'
is
false,
where
A is the
concept
of an
actual individual,
the
combination
'AB'
will
not
even
be a t
-stage
in the
concept
of any
possible
individual. Worse,
if
both
A and B are
complete
individual
concepts
and are
not
identical,
it is
hard
to see any
plausible interpretation whatever
for
'AB'.
Leibniz
does
not,
so far as I
know, ever
face
these
difficulties.
The
universal
affirmative
existential propositions
'Every
A is
B'
will
also
have
to
have
a
time parameter because
it can
(and often does) happen that
sometimes
all the
individuals
falling
under
A
will
fall
under
B and at
other
times this
will
not be the
case.
For the
same reason
as
before,
we add the
index
to the
copula rather than
to the
predicate. Then, existential
(6)
'Every
A
is,
B'
is
true
if and
only
if, for
every complete individual
concept
C
belonging
to the
actual world,
if the
/-stage
of C
contains
A,
then
it
contains
B.
Again,
it
seems
safest
to
restrict
t to
designations
of
time
in the
actual
world.
24
Thus,
all the
existential propositions
'Every
man
is,
liable
to
sin'
are
true
because (according
to
Leibniz,
as I
read him) every actual
person
is at all
times
liable
to
sin. This case suggests that when dealing
with
existential
propositions,
we
might reintroduce
the
notation
'Every
A is
B'
for
'For
all t,
every
A
is,
B',
and, similarly,
the
notation
'A
is
B'
for
'For
all t, A is,
B'.
25
And, since
one of the
advantages
of
propositions over sentences
is
supposed
24
Thus, when
the
universal
affirmative
is
taken
existentially,
Leibniz agrees with Hobbes.
Cf.
the
quote
from
Hobbes
cited
at NE 450 n.
1:
"When
two
names
are
joined together into
a
consequence,
or
affirmation,
as
thus,
'A
man is a
living
creature',
...
if the
latter name
'living
creature'
signify
all
that
the
former name
'man'
signifieth,
then
the
affirmation,
or
consequence,
is
true;
otherwise false."
Leibniz
seems
to
hold that
in the
case
of
nonactual things
"we
cannot
say
whether they exist
now or
not" (see
chap.
4, n.
20). Therefore,
he
perhaps would
wish
to say
that such propositions
as
"Bcllerophon
is now
riding Pegasus"
and
"All unicorns
are now
horses"
are
either nonsense
or
without
truth value,
and not
false.
In any
case,
they
would
not be
true.
25
More
strictly,
the
sentence
'Every
A is
B'
can be
reintroduced
as
short
for the
meta-
theoretical statement that
all
sentences
'Every
A is,
B'
for
all
time designations
/,
are
true; e.g.,
'All
men are
liable
to
sin'
could
be
short
for
"For every time designation
t,
'All
men
are, liable
to
sin'
is
true."
Needless
to
say,
I am not
claiming that Leibniz
had any
such
scheme
explicitly
in
mind.