Arguments and sub-arguments

51 Pages·2012·0.13 MB·English

by  Austen Clark

Arguments & sub-arguments
Philosophy and Logic
Section 4.1
Unit 4. Analyzing Inferences
• Applied at last to real-life arguments
– ex. 4.1, 4.2, & pp. 4-23 through 4-28
• Add suppressed premises
– ex. 4.3, 4.4, p. 4-22.
• Give a technical definition
– suppressed premise, weak/strong statement/
argument, principle of charity, strawman
Constructing an argument
The dollar will fall in value against the yen, and if
the dollar falls against the yen, then the trade
deficit with Japan will get worse. So the trade
deficit with Japan will get worse.
F
(cid:201)
F W
-------------------------------------
W
But what if your audience does not believe that the
dollar will fall in value against the yen?
The author’s burden
• You want to persuade someone that your
main conclusion, Q is true.
• To do this generally you must dig down
until you find premises P which that person
already believes or will accept, and then
show that
(cid:201)
(P Q)
Author’s burden (cont.)
• If they don’t believe that the dollar will fall
against the yen (F), you must give an
argument that F.
• More generally: almost any premise might
reasonably be challenged
– If it is challenged, you should be ready with a
back-up argument for that premise.
– These “subsidiary” arguments are often given
with the “main” argument itself.
Why the dollar will fall
Treasury bill rates are going down, and if they
do, then the dollar will fall against the yen.
Hence the dollar will fall against the yen.
T
(cid:201)
T F
-------------------------------------
F
A more complex structure
T
(cid:201)
T F
--------------------------
F
F
(cid:201)
F W
--------------------------
W
A more complex structure
T
(cid:201)
T F
--------------------------
F
F
(cid:201)
F W
Main argument
--------------------------
W
The MAIN conclusion
A more complex structure
T
(cid:201)
T F
A “mini” argument
--------------------------
F
F
(cid:201)
F W
Main argument
--------------------------
W
The MAIN conclusion
A more complex structure
T
(cid:201)
T F
A “mini” argument
--------------------------
F
Premise F is its conclusion
F
(cid:201)
F W
Main argument
--------------------------
W
The MAIN conclusion