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Lecture Notes: October 21
In the following, references to the section numbers of the texts are recorded as S29, for example.
Basic
metaphysical question, for everyone: What exists?
Descartes says that physical objects both can and do exist.
He basically agrees with the new science, as does Locke, which countenances
a world of material objects.
But what are these objects like?
We think of these objects through use of the imagination (images), in part.
For Descartes, though, these images are confused, subject to the faults of the
resemblance hypothesis.
The only real properties are those we can understand by pure reason: mathematical
ones.
Locke worries about Descartes' notion of pure reason. Two problems for pure reason:
Problem #1: How can an idea be innate? (MV,5)
For Descartes, which ideas are innate? -God, math, tautologies
Some we don't know - Goldbach's conjecture, children don't know any.
Descartes' solution: We reason to find them out.
Kant attempts to solve this puzzle by introducing the notion of the synthetic
a priori
Locke's solution: We learn particulars, then generalize to find universals.
The mind is a blank slate (tabula rasa)
Nobody questions
whether experience is necessary for us to know these ideas.
The question is whether it is sufficient.
(E.g. keys are necessary to drive a car, but not, in themselves sufficient)
Locke says it is sufficient: All knowledge derives from experience. (Empiricism)
Problem for empiricists: how do we explain the certainty (or necessity) of 2+2=4,
and other math facts?
No possible experience can support it.
How do we know how to generalize?
Descartes says experience is not sufficient. (E.g. chiliagon, star v flame,
wax)
Problem #2: How
can we learn about objects by using our reason, not our senses?
Descartes rejects the resemblance hypothesis completely.
Locke says that we do use the senses to learn about objects
Consider S21: temperature experiment.
What properties
do objects really have?
Descartes says we can't trust the senses at all.
Locke thinks that's throwing out too much.
Our senses do give us some misrepresentations.
But some sensory evidence is useful as a conduit to knowledge.
If we had no senses, we couldn't even start to understand the physical objects.
Why would we even posit them?
Descartes and
Locke both hold the representational theory:
Ideas are like pictures in the mind.
The resemblance hypothesis says that these pictures are a fair representation
of reality.
Descartes says that we have to reject this sensory information.
Locke says it's partially veridical.
Our ideas are complicated: our experience with fire: heat, yellow, blue, pain,
scary, odor of wood
For Locke, some of those experiences are about us, others are really about the object.
How do we draw
the line?
Compare shininess or red to mass or configuration of subatomic particles.
Principle #1:
If an object seems (to one person, or to two) to have two incompatible properties,
then it must really have neither property:
Compare to Descartes's discussion of the wax.
Consider Locke's discussions of hot and cold (in S21), porphyry, which loses
color in dark (in S19), and the almond, which changes taste and odor (in S20)
Corollary to Principle #1: Even if a change in us entails the change in the perceived quality, it can't be a real quality.
Then we're like two people: one before and one after.
Principle #2:
If an object has the same property under all conditions, it must really have
that property.
Read S9: "Qualities such as are utterly inseparable from the body..."
Corollary to Principle
#1: If every one has the same impression, then it must really have that property.
S21: the discussion of figure
Locke calls the real properties 'primary qualities' and the subjective ones, which are not really qualities of the object, 'secondary qualities'.
S23:
Primary Qualities:
Solidity
Extension
Figure
Motion/ Rest
Number
Secondary Qualities:
Color
Odor
Hot/ Cold
Sound
Texture
Taste
Notice that the Secondary Qualities are the sensory properties.
So Locke accepts the Resemblance Hypothesis (S15), for primary qualities only.
But we see yellow lemons!
Corpuscular Theory (Atoms): There's something in the object that makes me think
it is the way it is.
Dispositional properties. (S13)
Primacy of Mathematics:
primary qualities are mathematically describable.
Much like Descartes, but with a wider set of properties, and resemblances.
Not original with Locke (1689). Democritus and atoms. Boyle in the 1660s.
Galileo (1564-1642):
That external bodies, to excite in us these tastes, these odors, and these sounds, demand other than size, figure, number, and slow or rapid motion, I do not believel and I judge that, if the ears, the tongue, and the nostrils were taken away, the figure, the numbers, and the motions would indeed remain, but not the odors nor the tastes nor the sounds, which, without the living animal, I do not believe are anything else than names...
Nominalism: some
words don't denote real objects or properties, but are merely names.
We are all nominalists about fictional objects, like Pegasus.
Some people are nominalists about numbers.
Locke is a nominalist about color, and the other secondary properties.
The empiricist picture is that we have ideas, these impressions on our minds, arising from the senses and their interaction with the material world, which exists independently of us, but which depends on us for sensory properties.
Descartes' take
on the physical world was implausible, but he had an account of our knowledge
of mathematics and science: pure reason.
Locke rejects this, and produces a more intuitive take on the physical world,
relying on the senses.
But what about mathematics, then?
Recall Descartes mental philology:
A) Innate
B) Acquired
C) Produced by me
Locke rejects anything of type A)
Math must then be either of type B) or of type C).
But Descartes' objections to these still stand.
Berkeley, while
accepting Locke's empiricism, claims that Locke's account depends on the doctrine
of abstract ideas.
We sense particulars, the representations that come from the flow of the passing
show.
Then, we generalize, forming an abstract idea, like that of a circle, or of
a two.
Locke's commitment to abstract ideas, for Berkeley, creates a problem for his
commonsensical metaphysics.
An Empiricist
Problem:
1) All knowledge comes from experience
2) We experience sensations, not their causes
3) So we have no knowledge of what causes our sensations, i.e. objects and the
material world.
That is, how do we know about objects?
Descartes: We
judge with our minds.
Locke: Primary qualities inhere in material objects; our ideas resemble them.
Berkeley: There are no material objects!
See S4, S9
3 metaphysical
positions:
Idealism: All reality is mental (Berkeley)
Materialism: All reality is material; the mental is physical (Hobbes, sort of
like Locke)
Dualism: Some reality is mental, some physical (Descartes)
A glimpse into
Berkeley's claim:
1) materialism (and the materialistic side of dualism) leads to skepticism and
atheism.
We can't get out of our heads into those objects, so we are forced into skepticism
(S86, and following).
We claim that our sensations depend on a world of objects, and we seem to dismiss
God from our natural science (S92).
2) skepticism and dualism are wrong.
So, Idealism is right.
Another take:
(S73)
We posit matter to account for the ideas we can't control.
Then, with Locke and Galileo, we realize that many of these properties aren't
material.
Eventually, we realize that it's all mental, even if, in some non-spatial way,
external.
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