Voltaire’s Criticisms
Berkeley had two principal arguments to
prove that we do not directly perceive the
extension of bodies:
 perceptual relativity arguments
(esp. with regard to variations in
magnitude)
 anti-abstraction arguments
Both sorts of arguments fail and therefore
he does not prove his case.
Against Perceptual Relativity Arguments
There are two kinds of magnitude:
 apparent magnitude
 real magnitude
Apparent magnitude is measured by the
number of minimally visible or tangible
points a thing takes up (or the angular
portion of the visual field it takes up.
Real magnitude is measured by moving a
standard unit end over end along a line.
While apparent magnitude varies with
distance, real magnitude (which is also
perceived) does not.
Whether you are close to an object
or far away, the reading on the tape
measure is the same.
Reid’s Later Expansions on Voltaire’s Point
There are no perceptual relativity
arguments concerning tangible position or
figure.
(The arguments concern differences
between vision and touch, or
differences between different views
of the same object.)
The perceptual relativity arguments are
based on a misunderstanding of what it is
that vision tells us about.
Vision tells us just about the compass direction
and elevation (“right-ascension” and
“declension”) that each of the parts of an object
has relative to the position of the eye.
Touch tells us about the position that each of
the parts of an object has relative to one
another.
So vision and touch are not telling us different
things about the same object, but about
different features of the same object:
 visible position and figure (the figure
formed by the combination of the
visible positions of all the parts)
 tangible position and figure
Visible position and figure should vary with
changes in position and distance, since they
are relative to the position of the perceiver.
Against the Anti-Abstraction Argument
“… extension is not a feeling.”
So when we perceive extension we
are not having feelings = sensations,
and so not perceiving a “sensible
thing”
we are instead perceiving a real
object.
Reid’s Expansion on this Argument
Our sensations of smell, taste, sound, heat &
cold, and even pressure and pleasure/pain are
not extended.
Our sensation terminology is
ambiguous, sometimes referring to the
cause of a feeling, sometimes to the
feeling.
In no case (even that of colour) do we think of
the feeling (the state of mind we are in and that
exists only in us and only when perceived) as
being extended or as having position, figure, or
magnitude.
We only think this of the cause of the sensation.
So, Berkeley’s claims notwithstanding, primary
qualities not only can be abstracted from
secondary qualities, they are never in fact
perceived together.
Problems with the Voltaire/Reid case for
distinguishing sensation (of secondary qualities)
from perception (of primary qualities)
 pains and other tactile sensations have
location relative to one another
 Reid is just wrong about colour
Boullier’s “Transcendental” Argument for
the Existence of Body
“… the whole commerce of the life of men depends
on this agreement in the perceptions that all have of
one and the same world as their object and center.
Without that, men would not be able to understand
each other, or unite together, or communicate with
one another in the course of their actions. If we
consider society in relation to … its natural state,
that [reciprocal] bond [between the people who
compose it] is formed by [their] common ideas of a
shared world that they take themselves to inhabit.”
We are able to understand one another and
communicate with one another in the course of our
actions.
Insofar as we do this, we have to understand how
the objects we are dealing with look from the
perspective of others.
When we do that we suppose a common space in
which we are all located at different positions with
regard to the object and calculate how the object
must look to others by projection in that common
space.
So the supposition of the existence of an external
world is a necessary condition of the possibility of
mutual understanding and communication.
(Even if there is no such world, we are
necessarily compelled to suppose it and to
act as if it existed.)
This makes it very likely that God would have in fact
created such a world — rather than create an
illusion that we really are incapable of escaping.
Kant’s ill-informed understanding of
Berkeley
Kant: Berkeley’s claim that matter is
impossible rests on appeal to the
paradoxical consequences of the infinite
divisibility of space.
(In fact, it rests on no such claim.
The appeal to infinite divisibility is
Kant’s own [Leibnizian] argument for
denying that things in themselves
exist in space.)
Kant’s “Refutation of Idealism”
(another “transcendental argument”)
“I am conscious of my own existence as determined
in time. All determination of time presupposes
something permanent in perception. This
permanent cannot, however, be something in me,
since it is only through this permanent that my
existence in time can itself be determined. Thus
perception of this permanent is possible only
through a thing outside me …”
“… space alone is permanent, while time, and
therefore everything that is in inner sense, is in
constant flux.”
My experience of myself and my own
internal states presupposes an experience
of things in space.
Because:
I experience myself as “determined
in time” (as having different
experiences or ideas over time)
But all determination of temporal
relations presupposes reference to
something permanent in perception.
Because:
To think that one idea follows another (as
opposes to coexisting with it or preceding it)
is to think that there is some enduring thing
of which the one idea is a later state and the
other an earlier state.
This permanent thing could not be
myself or my mind.
Because:
I have no experience of any such thing. All I
find in myself by introspection is a collection
of ideas occurring in constant flux.
In fact, nothing that exists only in
time is permanent; the only thing that
is really permanent and enduring
over all of time is space.
Because:
Space and all its parts are eternal and
unaltering (one part of space does not move
with respect to the others and none is ever
annihilated or created).
Each of the parts of time exists only for an
instant. So what is only in time (except for
space and what is spatial) is impermanent.
Consequently, it is only through
being considered to be states of
something that is located or moving
in space that what exists only in time
can be considered to be successive
rather than simultaneous, or
successive in one order rather than
the reverse order.