On 11/20/02 6:28:00 PM, Lisa Loennig
wrote:

>Induction- Reasoning from the
>specific to the general
>Deduction- Reasoning from the
>general to the specific.

Everything else looked fine, but this isn't
quite right. Deductive arguments are
arguments which guarnatee their
conclusions. Example:

All men are mortal
Socrates is a man
Therefore, Socrates is mortal.

If we KNOW the premises are true, the
conclusion MUST be true, as a matter of
logic. These kinds of arguments are
either valid or invalid, there is no
in-between. Either the conclusion is
guaranteed 100% by the premises or it
doesn't do anything to prove the
conclusion.

An inductive argument, on the other hand,
only establishes its conclusion to a
degree of probability. For example:

The suspect's DNA was found at the
crime scene.
Three witnesses identify the suspect at
the crime scene.
The suspect had a good motive to
commit the crime.
Therefore the suspect is guilty.

There's always the possibility that even if
all the premises are true, the conclusion
could be false. For instance, in the case
above the suspect could have a long lost
twin brother who committed the crime.
Not very likely, but it is possible.

Hume's problem with induction is that it
can never give you complete certainty. It
used to be a textbook case for illustrating
induction to say "Every swan so far
observed is white, therefore all swans are
white." Seems like a good argument. But
they discovered swans in Austrailia which
were black. Hume's take on induction is
that since it's mere guesswork. There's
no logical reason why patterns in the past
should continue on into the future. This is
part and parcel of his analysis of cause
and effect.

However, Hume also criticises Descartes
for using a priori deductions to prove
truths about the world. According to
Hume, all concepts can tell you about are
other concepts or what *doesn't* exist;
you can't prove what *does* exist through
a priori deductions. Deductive reasoning
can tell you, for instance, that there are no
round squares or married bachelors. But
it can't tell you whether the table in my
living room is round or square or whether
*I* am married. For "Matters of Fact and
Existence" (Kant's synthetic truths), you
need to use your senses. Thus, Hume
criticizes Descartes, who thinks you can
prove "matters of fact and existence" a
priori.

Recall how Descartes argues: God is a
perfect being, existence is a perfection,
therefore God possesses existence. God
is perfect, a perfect being contains all
perfection, moral goodness is a
perfection, therefore God is good. A
perfectly good being could not be a
deceiver, therefore God is not a deciever.
If the world an illusion or a dream, God
would be a deceiver, therefore, there is a
real world which we can know...etc.

Hume says this approach is
fundamentally flawed, like trying to use a
fork to eat soup. The only way to settle
"matters of fact and existence" (synthetic
truths) is through the senses.

Prof. Borrowdale
borrowdalej@lanecc.edu
541-463-5434