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

• 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 response-dependent: 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

•

IdeaAppearance

This is a triangle

Understanding

PerceptionThing in itself

Abstraction

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. . . .”