Transcript Metaphysics in Early Modern Philosophy

Metaphysics in Early Modern
Philosophy
The Atomic Theory of Matter
• The atomic theory poses a challenge to
theories of substances or objects
• Atomic theory: things are composed of atoms;
properties of things depend on nature and
motion of atoms
• Things are not as they appear
Appearance and Reality
• Aristotle: objects cause perceptions, and are
represented in them
• Causes of perception = objects of perception
• Atomic Theory: No—
– causes are the atoms— which are real
– objects are appearances
Causes and Effects
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Causes of perception are the atoms
We don’t see atoms, but their effects
What we see doesn’t exist in reality
How can we distinguish the aspects of the
effects (appearances) that do match the
causes?
Primary Qualities
• Descartes: We perceive
clearly and distinctly only
the mathematical properties
of objects: size, shape,
motion
• Only they reflect the true
natures of things
Primary Qualities
• Locke: Primary qualities are
inseparable from objects;
atoms have them
• Primary qualities are those
objects possess according
to the atomic theory of
matter
• They produce simple ideas
in us that resemble the
primary qualities in the
objects
Secondary Qualities
• Secondary qualities are effects of objects
on our nervous systems
• They produce ideas in us that do NOT
resemble them
Secondary Qualities
• Secondary qualities depend on primary
qualities
• Secondary qualities are responsedependent: to have one is just to
produce a certain effect in a perceiver
Primary and Secondary
• Primary qualities: mathematical properties,
assigned to atoms by physical theory— e.g.,
size, shape, mass, motion
• Secondary qualities: effects of primary qualities
on us— e.g., color, texture, moral and aesthetic
qualities
• To be red is just to look red to a standard
perceiver in standard conditions
Real and Nominal Essence
• Aristotle and Aquinas identify:
– The essence of x = the properties necessary to x
– The quiddity of x = the definition of x in re
– The nature of x = what makes x what it is
• Locke: nominal essence = quiddity: uses
secondary qualities
• Real essence = nature: real internal constitution
Real and Nominal Essence
• Gold
– Nominal essence: heavy yellow metal
– Real essence: element with atomic number
79
• Water
– Nominal essence: colorless, tasteless liquid
(at common temperatures) necessary to life
– Real essence: H2O
Locke’s Philosophy of Mind
Understanding
•
This is a
triangle
Idea
Appearance
Abstraction
Perception
Thing in itself
Real Essences
• Aristotle and Aquinas: We know objects by grasping
their essences
• Locke: Which essence?
– Nominal: concept; conditioned
– Real: real internal constitution; unconditioned
• We study cognition as we study anything else
• We know real essences through scientific method
Idealist Critique
• We know world only through sense organs
• So, we know objects only insofar as they
become internal objects
• They are objects of consciousness,
constituted by consciousness
• We know objects only as conditioned by
consciousness
Argument for Idealism
• We have reason to believe that something
exists only if we can know it
• We can know an object only by making it an
object of consciousness
• Any object of consciousness is conditioned
by consciousness
• Anything conditioned by consciousness is
mind-dependent
• So, we have reason to believe that a thing
exists only if it is mind-dependent
George Berkeley (1685-1753)
• Idealism best defense of
common sense against
skepticism
• Descartes’s and Locke’s ideas
of objects make no sense
• Attack on primary qualities
and on substance
Against Primary Qualities
• We have no basis for thinking any of our ideas
corresponds to some mind-independent reality
• We cannot judge resemblance to reality
• Perceptions of width, height, etc., vary while
objects remain unchanged
Esse est Percipi
• We have access only to what is before the
mind
• A thing can exist only if it is perceived
• Do things go out of existence when we
aren’t looking at them? No— because
God keeps an eye on them for us
David Hume (1711-1776)
True of all objects
• Example: Heraclitus: can’t step in
same river twice
True of all objects
• The ship of Theseus
• Plutarch: “The ship wherein Theseus and the youth of
Athens returned [from Crete] had thirty oars, and was
preserved by the Athenians down even to the time of
Demetrius Phalereus, for they took away the old planks as
they decayed, putting in new and stronger timber in their
place, insomuch that this ship became a standing example
among the philosophers, for the logical question of things
that grow; one side holding that the ship remained the
same, and the other contending that it was not the same.”
Successions
• “. . . the objects, which are variable or
interrupted, and yet are suppos'd to continue
the same, are such only as consist of a
succession of parts, connected together by
resemblance, contiguity, or causation. . . . all
objects, to which we ascribe identity, without
observing their invariableness and
uninterruptedness, are such as consist of a
succession of related objects.”
Fictitious Identity
• “The identity, which we ascribe to the
mind of man, is only a fictitious one. . . .”
Imposed Identity
• Mental states link to other mental
states: memory, intention, desire,
similarities
• We construct the idea of self
• Self is not a unified thing— best
compared to a commonwealth
• Questions about identity aren’t about
the world, but about language
Verbal Disputes
• “. . . all the nice and subtle questions concerning
personal identity can never possibly be decided, and
are to be regarded rather as grammatical than as
philosophical difficulties. . . . as the relations, and the
easiness of the transition may diminish by insensible
degrees, we have no just standard, by which we can
decide any dispute concerning the time, when they
acquire or lose a title to the name of identity. All the
disputes concerning the identity of connected objects
are merely verbal. . . .”