Posted: March 2nd, 2017

From the textbook, 14th edition.

9.2, argument 2.

Here follows a set of twenty elementary valid arguments. They are valid because each of them is exactly in the form of one of the nine elementary valid argument forms. For each of them, state the rule of inference by which its conclusion follows from its premise or premises.

( D v E ) ⊃ ( F v G )

Therefore D v E

9.3 Ex. 3

Each of the following exercises presents a flawless formal proof of validity for the indicated argument. For each, state the justification for each numbered line that is not a premise.

1. I ⊃ J

2. J ⊃ K

3. L ⊃ M

4. I v L

Therefore K v M

5. I ⊃ K

6. (I ⊃ K) AND (L ⊃ M)

7. K v M

9.4 ex. 9

A formal proof for each argument may be constructed by adding just two additional statements. This will be an easy task if the nine elementary valid argument forms are clearly in mind.

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