Friday, September 2, 2005

Deductive & Inductive Arguments - Salmon

(Originally written September 2, 2005 in Book 1)


Logic
Wesley C. Salmon
1963

Deductive & Inductive Arguments

- Deductive and inductive arguments are defined by certain fundamental characteristics

- In deductive arguments if all the premises are true, the conclusion must be true
- In deductive arguments all of the factual content was already contained, at least implicitly in the premises
-In inductive arguments if all the premises are true, the conclusion is probably true, but not necessarily true
-In inductive arguments the conclusion contains information not even implicitly present in the premises
-Deductive arguments are wholly correct or wholly incorrect. If the premises are true than the conclusion is true. If the premises are false, then likewise, the conclusion is false.
-Inductive arguments offer partial conclusiveness because the premises are used as strengthening for the conclusion, not absolute factual basis.
-Deductive arguments cannot offer partial conclusiveness because they do not account for any variation. Inductive arguments do.

Examples: 

Deductive:
1. Every mammal has a heat
2. All horses are mammals
3. Therefore, every horse has a heart.

Inductive:
1. Every horse that has ever been observed has had a heart.
2. Therefore, every horse has a heart.

Both deductive and inductive arguments come to the same conclusion that, "every horse has a heart". But, because the inductive argument used the phrase, "that has been observed" it leaves the door open in case there comes a horse that is observed with no heart. This leaves room for both error and correction.

-The relation between scientific generalization and its supporting observational evidence is inductive.
-Mathematical argument is deductive.
-Deduction has a severe limitation because the conclusion is located in the premises, whereas induction can use more implicitly stated truths in the premises
-Deductive arguments cannot be found logical if they overstep the boundaries of their premises  

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