November 11

Lecture Notes: November 11

References herein to Hume's work are via page numbers in the Hackett.

Hume

Epistemology is the study of knowledge.

In doing epistemology, we attempt to answer questions like the following:

How do you know? (Or, Why do you believe?)
1) You are taking a philosophy class?
2) Your best friend likes you?
3) Enron committed accounting fraud.
4) Shakespeare wrote The Tragedy of Macbeth?
5) 2+2 = 4?
6) The sun will rise tomorrow?
7) F=ma?
8) Every effect has a cause?

The answers may be very different.
The answer to 1) might be from some kind of introspection.
The answer to 8) might be some kind of scientific principle, or assumption about the world.

The last four are all problems for empiricism

Empiricists may deny in fact that we know such claims.
For example, some empiricists are nominalists, saying mathematical terms are non-referring names: there are no objects to correspond to the names 'circle' or '2' for example.
Fictionalism is a currently popular position in the philosophy of mathematics.

Fictionalists claim that mathematical objects are convenient fictions.
Berkeley is a nominalist about mathematics,
He rejects the possibility of infinite divisibility (a basis for the calculus) and affirms the presence and importance of a minimum sensibilia: the smallest possible perceivable extension.
Similarly, Berkeley regards scientific laws as regularities, provided by God for convenience, but with exceptions (miracles)
These regularities, as abstract ideas, are not real ideas
See Hume, with Berkeley, against abstracta (p 106)
So why should we believe in empiricism?

Hume's argument for empiricism:

1) All our beliefs about the world are based on our beliefs about cause and effect relations.
2) All our beliefs about cause and effect relations are based on experience, not reason.
:. All beliefs about the world are based on experience.
That is, empiricism is true.
We'll see how he supports the premises later.

Hume and Locke are trying to do for philosophy what Galileo and Newton did for science.

What were their achievements?
(What exactly did Newton discover with the apple?)
1) No natural center of the universe.
2) Motion is simply change of place, not development toward some fulfilling goal (teleology). There are universal laws of motion that apply both on Earth and elsewhere.
3) Rest is simply a limiting case of motion, not the final fulfillment of a goal. Rest, like motion, is a normal state which doesn't need to be explained in terms of final causes. Both can be explained by the laws of motion.

So, what are these laws? How do we know them?
Newton says that these Principles of Explanation are to be "deduced from the phenomena".

E.g. gravity: we see it work in various cases, it applies broadly, to both the apple and the waves, and all of the time.
So, we reason, using induction:

In all events (E1, E2, E3.... En) the law applies.
Thus, in all similar cases, this law must apply.

Induction: deriving a general law from particular cases (generalizing).
Contrast with deduction: deriving a particular instance from broad, general laws.
Induction, the foundation of all science, relies on analogy (p 69).
Scientific laws are thus generalizations from experimental evidence.

What are the phenomena which found these generalization? That is, where do we get all the En?
For empiricists, like Locke (as we read him) and Berkeley, and for Hume, there is only one answer: from the senses.
All knowledge is, or must be traced back to, ideas and impressions (10)
An impression is an occurent mental state, e.g. the feeling of a hand on a burning stove
An idea does not have to be of something happening at the moment, e.g. the thought of that burning sensation 10 minutes, or an hour, or a year later.
The mind has simple ideas and complex ones.
The simple are derived directly from impressions.
What about unicorns? We have ideas of these without ever having an impression of one.
They are complex ideas, made up of combinations of simple ideas.
There is a limited exception to this general rule: missing shade of blue (p 12-3)

So, only assertions traceable to simple ideas can be supported, according to Hume. (p 13)
That is, everything must be supported exclusively by sensory evidence.
But scientific generalizations go beyond sensory evidence, through the inductive generalization.

Can we justify the inductive leap?
Descartes: evidence of reason.
That won't work for Hume: See pp 93-4.
This eliminates justification of all scientific claims.

It's not just that physical laws like Newtonian gravitation, or laws of gases, etc. are derived from experimental evidence.
Even the existence of a physical world is a scientific hypothesis generated by experience. See PP 104 and 107.

Hume agrees with Berkeley on the primary/secondary distinction and impossibility of proving the external world via experience, but rejects recourse to God. See p 105.
The God hypothesis goes beyond legitimate inference, goes beyond the data.

So, Hume is a revolutionary, attempting to clean philosophy of illegitimate philosophical speculation:
"When we run over libraries, persuaded of these principles, what havoc must we make? If we take in hand any volume - of divinity or school metaphysics, for instance - let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames, for it can contain nothing but sophistry and illusion. (p 114)

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