2
The History of Ancient Greek Philosophy
•
Focused on the Philosophy of Nature
– Ionian Philosophy of Nature (6th Century BC)
• (not covered in this course)
– Parmenides’ Challenge (early 5th Century BC)
PHIL 115
– Two Mature Responses to Parmenides
• Democritean Atomism (late 5th Century)
• Aristotelian Hylomorphism (mid-4th Century)
•
Focus on Philosophical Anthropology
– Democritean (Monistic) Materialism
Lecture #10:
Democritus
– Platonic Dualism
– Aristotelian Hylomorphism
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4
The Atomists
•
•
Democritus
•
Leucippus (!"#$%&&'() (early C5 BC)
– All sources cite Leucippus as founder of this doctrine, but not
a lot is known about him & there is not always much point in
trying to distinguish him from his disciple.
Democritus ()*+,$-%.'() of Abdera (460-370)
– We have more material from Democritus, who must be judged
the most prominent of the early atomists
Later atomism becomes an element of Epicureanism.
– So, a good later source of the doctrine is Lucretius’ De Rerum
Natura (95-55 BC).
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6
Atomist Epistemology
(Theory of Knowledge) I
•
Atomist Epistemology II
•
There are two kinds of knowledge:
1. Obscure sense-knowledge. This is knowledge of the ordinary properties of
ordinary objects (e.g., of the color of a flower). This knowledge comes
from the senses. Why is it obscure?
2. Genuine knowledge. This is knowledge of fundamental objects (i.e., of the
atoms). This knowledge comes from reason, the “finer means.”
•
The argument for the relative obscurity of sense-knowledge.
Any
[All]
So, [All]
thing that shifts its character
according to the body’s
dispositions, influences, and
confrontations
Sense-knowledge
Sense-knowledge
is obscure.
shifts its character
according to the body’s
dispositions, influences,
and confrontations.
is obscure.
The role of the senses
– Limited
• “By convention there is sweet, by convention there is bitter, by
convention hot and cold, by convention color; but in reality there are
only atoms and void.”
– But necessary
• “A dialogue between the intellect and the senses:
– Intellect: It is by convention that color exists, by convention sweet,
by convention bitter.
– Senses: Ah, wretched intellect, you get your evidence only as we
give it to you, and yet you try to overthrow us. That overthrow will
be your downfall.”
Atomist Ontology
(Theory of Being)
Background to Democritean Atomism
•
There are two fundamental principles, each grounded in a distinction:
1. “The existence of the non-existent”
The distinction is between
two kinds of space
the full &
the empty
(or) two kinds of being
atoms (matter) &
the void
2. “The macroscopic is made up of the microscopic”
(or, Ordinary objects are made of very small particles [atoms]) (reductionism).
The distinction is between
ordinary objects &
indivisible [i.e., atomic] particles
•
•
Greek philosophy of nature began with an attempt to identify the principles
underlying the natural world
– that was a world made up of many things
– those things were subject to change
Parmenides presented a challenge to the very possibility of such a world
Democritus’ philosophy was a response to that challenge
9
Parmenides of Elea (c. 540–470):
His Account of the World
Sir Arthur Eddington in his 1928 Gifford Lectures:
“I have settled down to the task of writing these lectures and have
drawn up my chairs to my two tables. Two tables! Yes; there are
duplicates of every object about me—two tables, two chairs, two pens.
…
“One of them has been familiar to me from earliest years. It is a
commonplace object of that environment which I call the world. How
shall I describe it? It has extension; it is comparatively permanent; it is
coloured; above all it is substantial …
“Table No. 2 is my scientific table. It is a more recent acquaintance
and I do not feel so familiar with it. It does not belong to the world
previously mentioned that world which spontaneously appears around
me when I open my eyes, though how much of it is objective and how
much subjective I do not here consider. It is part of a world which in
more devious ways has forced itself on my attention. My scientific table
is mostly emptiness. Sparsely scattered in that emptiness are numerous
electric charges rushing about with great speed; but their combined
bulk amounts to less than a billionth of the bulk of the table itself. …”
• His conclusion: The world is
– one
– indivisible
– immoveable
– unchangeable
• His premises
– It is. [B8]
– (Never will this prevail,) that what is not is. [B7]
• His method
– “Judge by the reason of this battle-hardened
proof.” [B7]
• This represents a challenge to the very possibility of a
philosophy of nature
Parmenides’ Argument
Against Motion
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This argument (and the next) are not based explicitly in any text of Parmenides or
Melissus, but seems to be the kind of argument that they might give, given what
else they say.
1. If things move.
then there must be an empty place to which
things can move.
1. M → E
2. If there is an empty place to which things can
move.
then there must be places in which there is
nothing [“non-being”].
2. E → P
3. If there are places in which there is nothing [“nonbeing”].
then non-being exists.
3. P → N
4. That non-being exists is absurd.
! 5. Things do not move.
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Appearance & Reality in
Modern Science
12
Parmenides’ Argument
Against Pluralism
1. If the world includes a number of distinct things,
then the things would have to be spatially separated
from one another.
1. P → S
2. If things are spatially separated from one another.
then they are separated by nothing [“non-being”].
2. S → Sn
3. If they are separated, but by non-being.
then non-being exists.
3. Sn → N
4. That non-being exists is absurd.
! 5. The world does not include a number of distinct things.
4. ~N
! 5. ~M
4. ~N
! 5. ~P
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Parmenides’ Argument
Against Change
1. If change occurs,
then something
existence.
Eleatic Philosophy
& its Pluralist Rivals
•
– There is no void, as a consequence of which
non-existent
comes
into 1. C → [Inc]
• Monism: There is no plurality.
• There is no motion.
– There is no change:
2. What can’t do anything can’t come into existence. 2. Eac
3. What does not exist cannot do anything.
3. Aea
[! "ec]
4. Non-existent things do not exist.
4. Ane
! 5. Non-existent things can’t come into
existence.
! 5. Enc
! 6. Change does not occur.
! 6. ~C
Democritus & the Void:
“The Existence of the Non-existent”
• There is no generation & corruption.
• There is no alteration (qualitative change).
•
15
•
This makes both pluralism & motion possible, as both Eleatic arguments depended on the
claims that:
– non-being does not exist
– empty space is non-being
What kind of argument can Democritus give for his view?
What Democritus &
Parmenides agree
on:
[motion] # [the non-existence of
non-being]
To this Democritus
adds:
Motion occurs.
So, Democritus
concludes:
[the non-existence of non-being] is
false
i.e., non-being (a void or vacuum)
exists
The Atomists were committed to refuting the arguments for these theses (or at least
to building up defensible alternative systems).
Experimental Evidence for
the Existence of a Vacuum
•
•
The Theses of Eleatic Philosophy
•
16
For, the Greek atomists,
– the assertion of the existence of a vacuum has explanatory power
– but its existence could not be shown more directly
The experimental creation of a vacuum was first accomplished by Otto von Guericke
of Magdeburg in the 1650’s.
– He pumped the air out of a device made of two copper hemispheres, after which
even two teams of horses could not pull them apart.
Parmenides affirmed the
other conjunct
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Democritean Atoms
• Indivisible (by definition)
• Immutable
– including ungenerable & incorruptible
• Many (= Quantitative Pluralism)
• Identical in kind (= Qualitative Monism)
– i.e., they all have the same properties
– though they differ from one another in
• size (as N vs. N)
• shape (as N vs. H)
• orientation (as N vs. Z)
• arrangement (as DOG vs. GOD)
• Movable
– hence, rearrangeable
• this is what makes change possible in ordinary objects
Democritean Atoms & Parmenidean Being
•
•
Atoms are like Parmenidean Being in some ways.
– Each atom is
• indivisible
– hence the name “atom”
• unchangeable
– since change was rearrangement of parts and atoms don’t have parts
• ungenerable & incorruptible
They are unlike it in others.
– Unlike Parmenides’ atoms
• There are many (Quantitative Pluralism)
• They are mobile
– the existence of the void allows for this
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Democritean Atoms &
the Atoms of Modern Science
•
Democritus’ atoms are different in important ways from the atoms of
contemporary science.
– Democritean atoms (upper box)
• They do not differ from one another in kind, but only in
– size & shape (Qualitative Monism)
– orientation
– arrangement
• They are indivisible.
• They do not change.
– The atoms of modern science (lower boxes)
• They differ from one another in kind: Carbon vs. Oxygen.
• They are divisible.
– They have parts (protons, neutrons, electrons) which (in the
case of nucleons) are themselves further divisible
– They can be split (in nuclear fission)
• They are changeable.
– In radioactive decay, an atom of one element becomes an
atom of another.
N
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Ordinary Objects
N
H
N Z
DOG GOD
•
Ordinary objects (the objects of sensible experience) are
– (trivially) like atoms
• many &
• moveable
– (importantly) unlike atoms, also
• composite
• divisible (into atoms), &
• changeable (by rearrangement of atoms).
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Differences in Ordinary Objects:
Diamonds & Graphite
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Differences in Ordinary Objects II
Your
Picture
Here
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Two Theories of Change
1. Parmenides & the Replacement Theory of Change
a. Parmenides presents the Replacement as the only possible mechanism of
change.
• Change is the ceasing to exist of one thing & the generation of another
thing in its place.
b. Change by replacement, he says, is impossible.
2. Democritus’ Rearrangement Theory of Change
a. Coming to be is an aggregation of parts.
b. Passing away is a dissolution of parts.
c. Change is a rearrangement of parts.
d. All of these are possible.
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Democritus’ Reply to Parmenides:
1. Motion
Parmenides’ Argument
Democritus’ Objections
(1) If things move, then there must be an
empty place to which things can move.
(2) If there is an empty place to which
things can move, then there must be
places in which there is nothing [“nonbeing”].
(3) If there are places in which there is
nothing [“non-being”], then non-being
exists.
“Non-being” here must mean empty
space.
(4) That non-being exists is absurd.
But that empty space exists is not absurd.
(Cf. F1, T4)
! (5) Things do not move.
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Democritus’ Reply to Parmenides:
2. Change
Direct Argument for
Democritean Atomism
•
Parmenides’ Argument
Democritus’ Objections
(1) If change occurs, then something non-existent
comes into existence.
(2) Non-existent things do not exist.
The arrangement that constitutes the ordinary object
does not exist;
but the atoms that make it up do.
(3) What does not exist cannot do anything.
Since the atoms exist, they can rearrange themselves.
(4) What can’t do anything can’t come into existence.
Since the atoms can rearrange themselves, the
ordinary object can come into existence.
Argument to the best explanation
– Fact: The world contains many things, each of which can move and
change.
– Warrant: The best explanation of those facts is Democritean atomism, since
• if the world were made up of mobile atoms it would behave the way it
does [predictive accuracy; scope]
• atomism is a reasonably economical theory [simplicity]
• it’s consistent with what else we know about the world [external
consistency]
– Conclusion:/(Probably) Democritean atomism is true.
! (5) Non-existent things can’t come into existence.
! (6) Change does not occur.
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Question
Democritus on Life
•
•
Reality—what kinds of
thing exist
Life in general
– The question—what gives some things the powers we call “life”?
• In particular, motion (both growth & local motion) & perception
• Democritus focusses on motion (as did Thales).
– Life-motion is made possible by a particular kind of atom
• “Soul atoms”—small, mobile, & dispersed throughout the body
• Their presence makes a body alive
• Their mobility causes the motion we call life
• At their departure, the body becomes dead
Human life
– Distinctive human powers—No Democritean account survives.
– Immortality
• Soul atoms are neither created nor destroyed
• But they disperse at death
• There is no aggregate of soul-atoms that continues to exist as “you”
Democritus
Atoms & the Void
(=occupied space & empty space)
Existence as a particular
kind of thing
or with a particular feature
particular arrangements of atoms
(atoms vary in shape & rotation, but not in kind)
features of perceptible world explained in terms of interaction of
atoms
Motion & Change
motion into empty space
all change is local motion of atoms
qualitative change is rearrangement of atoms
generation & corruption is congregation & dispersal of atoms
The composition of man;
the soul & death;
immortality
man as a collection of atoms
body—collection of atoms
soul—collection of a particular kind of atoms (highly mobile,
located throughout the body)
death is dispersal of the soul atoms
immortality not possible
Human activities &
capacities:
Physiological Processes
Sensation
Knowledge
incipiently mechanistic account of physiological processes
sensible qualities are a matter of convention; knowledge of them is
obscure
properties of the atoms are real; knowledge of them is genuine
knowledge grounded in senses but must transcend them
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Democritus’ Legacy
Democritus’
Legacy
NB: Three closely related ways of looking at his significance for contemporary
philosophy.
1. Materialism
- No non-material things exist
• perhaps in general
- no God or angels
• but especially as components of ordinary objects (e.g., man)
- No Aristotelian or Platonic forms
- No non-material souls
2. Reductionism
- Ordinary objects are nothing but collections of atoms.
3. Mechanism
- There is no difference in kind between organisms & machines.
- Living things can be analyzed by the same principles used in the analysis
of organisms.
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The Relation among the Three
Points of the Legacy
Democritus & Mechanism
•
• Materialists might be either
– Non-reductionists
– Reductionists, who might be either
• Mechanists (thinking that ordinary objects can be reduced to machines)
• Non-mechanists (thinking that ordinary objects can be explained in
terms of their parts [i.e., be reduced] but not to machines)
•
Materialism
Non-Reductionistic
Materialism
Reductionistic
Materialism
Non-Mechanistic
Reductionism
Mechanisistic
Reductionism
33
The Inspiration for Descartes’ Mechanical Physiology
Cartesian Physiology
•
Descartes was not a materialist
•
He made a sharp distinction between
Strictly, the idea of reducing human physiological & psychological processes to
machines was not Democritus’ idea.
– The kinds of machines used in classical Greece did not lend themselves to
such a comparison.
But early modern thinkers—two in particular—can be seen as extending
Democritus’ legacy in a natural direction.
1. René Descartes’ mechanistic physiology
• Man (1630-33; publ. 1662)
2. Julien Offray de la Mettrie’s mechanistic psychology (a comprehensive
mechanistic anthropology)
• The Man-Machine (1748)
– nor a comprehensive mechanist
– physiological processes, which he interpreted
mechanically, &
•
Tommaso Francini (1571–1651), Florentine
hydraulic engineer
•
a contemporary description of his work at the
Villa Medicea di Pratolino in Tuscany
34
– “At Pratolino, the statues turn about, play
music, jet streams of water, are so many and
such stupendous artworks in hidden places,
that one who saw them all together would be
in ecstasies over them.”
– psychological processes, which he thought were
• unique to man &
• spiritual rather than mechanical
•
He came to France in 1597, where he built the
grottoes of Château-Neuf in St.-Germain-enLaye for King Henry IV & his Medici queen
– These gardens included elaborate hydraulic
automata, e.g., a figure of Perseus which
descended to slay a dragon that arose from a
basin of water
– Descartes would have seen these gardens
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36
Mechanical Analysis:
A Complex Machine
De La Mettrie & the Man-Machine
• Descartes defended a dualist anthropology:
– A material body, a machine that carried out
physiological functions (such as digestion,
respiration, & growth).
– A spiritual mind (or soul), which was not
mechanical & carried out psychological
functions such as perception, emotions,
choice & thought.
• De La Mettrie extended the mechanical analysis
of human functions from the physiological to the
psychological.
•
All complex machines are combinations of simple machines.
– This derrick combines a wheel & axle with a pulley.
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38
Mechanical Analysis
Reduction of the Six Simple Machines to Two
Six Simple Machines (cont’d.)
<Inclined Plane
•
Lever>
Simple machines are used to transform forces, either
– changing their direction
– or changing the magnitude of the force.
<Wedge
Machines dependent on the
vector resolution of forces
Wheel & Axle>
Machines in which there is
an equilibrium of torques
The Analytically Simplest
Simple Machines
1. The inclined plane
4. The lever
Versions of the Simplest
Machines
2. The wedge—a
moving inclined plane
5. The wheel and axle
—a lever that can turn
360°
More Versions
3. The screw—helical
inclined plane
6. The pulley
<Screw
Pulley>
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Mechanical Analysis:
Three Kinds of Lever
A Mechanical Analysis of a Human Being I:
The Arm as a Lever
•
• A lever, by definition, is a rigid bar that pivots on a fixed point (the fulcrum).
– Its mechanical effects are produced by applying an effort at one point on
the bar
– and benefitting from the way the bar pushes on a load at another point.
First Class Lever
(Load—Fulcrum—Effort)
Second-Class Lever
(Effort—Load—Fulcrum)
Third-Class Lever
(Load—Effort—Fulcrum)
E.g., pliers
E.g., a nutcracker
The arm as a lever.
– The analysis of levers is based on the
relative position of fulcrum, effort &
load.
– The arm as a lever
• The elbow is the fulcrum.
• The effort is applied where the
muscle is attached to the bone of
the forearm.
• The load is usually placed on the
hand.
• So, the order is F—E—L, which
makes the arm a 3rd Class Lever.
E.g., tweezers
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A Mechanical Analysis of a Human Being II:
The Body as an Automobile
• (N.B. auto + mobile = self-mover)
• The arm is more than just a lever.
– It also has an engine (the muscles) & a fuel tank (the stomach).
• So, it is more like a machine that has an engine & a fuel tank, e.g., a car.
– An engine converts another form of energy (here, chemical energy), into
mechanical energy (motion).
A Mechanical Analysis of a Human Being IIIa:
The Mind as a Computer
•
Automobiles may move themselves, but they do not drive themselves.
– Perhaps the human being is not just an automobile, but an automaton (like
a robot or a Tomahawk cruise missile).
TERCOM = Terrain Contour Matching
DSMAC = Digital Sense Matching Area
Correlation
The Controversial Character of the Legacy
43
A Mechanical Analysis of a Human Being IIIb:
The Mind as a Computer
•
• The human brains is a network of neurons.
• In 1943, Warren McCulloch & Walther Pitts imagined an artificial neuron, which could
be built mechanically.
• The work of Alonzo Church & Alan Turing suggested that for any effective input-output
function, one can build a Turing machine that can take that input and produce that output.
• So, if human behavior is such an IO function, it can be duplicated by a machine.
consider four kinds of phenomena
– non-organic events (e.g., erosion, chemical reactions)
• why won’t neon combine with other chemicals?
• why does sandstone erode more easily than granite?
• structural explanation is most plausible here
– “vegetative powers” (reproduction, nutrition & growth)
• why do some zygotes develop into rabbits and others into frogs?
– “animal powers” (perception, emotion, locomotion)
• Democritean explanation in biology
– “Though the specifics of sensory processing vary among senses, the
principles of sensory function are always similar. Specialized neurons
called receptor cells transduce such natural phenomena as light energy and
sound waves into graded receptor potentials. Receptor potentials are
converted—either by receptor cells or by interneurons—into action
potentials that are processed by the CNS [central nervous system], where
perception occurs.”
—Levine & Miller, Biology: Discovering Life, p. 857
• plausibility of Democritean explanation (arguably) weakens
Structure of a McCullochPitts Artificial Neuron
input
weights
weighted
sum
function of
activation
44
output
– “human powers”—thought & choice
46
Summary
Democritus’
Philosophy of Nature:
Principles
Parmenides’
Account of Reality
P1. Change is
impossible
P2. Motion is
impossible
(Questions:
Why does he think
this?
How does it
constitute a
challenge to which
later philosophers
respond?)
D1. What exist are atoms &
the void (contra P1)
D2. Ordinary objects are
arrangements of atoms (contra
P2)
(Questions:
How does this make motion &
change possible?
How are they related to
contemporary ideas?)
Aristotle’s
Philosophy of Nature
(see upcoming lectures)
•
Democritus’
Legacy
1. Materialism
2. Reductionism
3. Mechanism
(Questions:
How are these related to
Democritus’ central ideas?
How can these ideas be used
to explain natural
phenomena?)
Democritus’
Philosophy of Nature:
Applications
1. Inanimate nature
2. Life
3. Consciousness & Thought
(Questions:
How can Democriteans
explain these phenomena?
Where does it work well &
where badly?)
•
Democritus thus laid the foundations for a philosophy of nature (& of man) that
has persisted down to our own day.
Two alternatives are more prominent in ancient philosophy
– Plato’s Idealism
– Aristotle’s Hylomorphism