Exercise III, p. 39-40:

Assume that the truth value assignments given to the right of each statement are correct.

     All my children are teenagers     (T)

     All teenagers are students     (T)

     All teenagers are my children     (F)

     All my children are students     (T)

Using these assigned values, label each of the following arguments as (a) valid or invalid, and (b) either sound or unsound.

(a) All my children are teenagers

      All teenagers are students    

      ---------------------------------------

      All my children are students 

(b) All my children are students 

      All teenagers are students    

      ---------------------------------------

      All my children are teenagers

(c)  All teenagers are my children

       All my children are students 

       ---------------------------------------

       All teenagers are students    

(d)  All teenagers are students    

       All my children are students 

       ---------------------------------------

       All my children are students 

Exercise V, p. 41:

Indicate whether each of the following sentences is true. For those that are true, explain why they are true. For those that are false, show why they are false by giving an example.

(1) Every argument with a false conclusion in invalid.

(2) Every argument with a false premiss is invalid.

(3) Every argument with a false premiss and a false conclusion is invalid.

(4) Every argument with a false premiss and a true conclusion is invalid.

(5) Every argument with all true premisses and a false conclusion is invalid.

(6) Every argument with a true conclusion is sound.

(7) Every argument with a false conclusion is unsound.

More questions:

A.            Construct Venn diagrams to test the validity of the following arguments.

1.                  All mothers are females

Some students are not females

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Some students are not mothers

2.                  All mothers are females

Some students are females

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Some students are mothers

3.                  No true sportsman is a cheater

All cheaters are dishonest persons

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No dishonest person is a true sportsman

4.                  Some epicureans are oenophiles

Some epicureans are philanderers

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some oenophiles are philanderers

B.            Construct Truth Tables to test the validity of the following arguments.

1.                  If I work then I earn money

If I don’t work then I enjoy myself

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If I don’t earn money then I enjoy myself

2.                  If Jones needs money then he will reduce prices and he will advertise

Jones will not advertise

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Jones does not need money

3.                  If Brown invests in real estate then if the market drops then he will lose money

The market will not drop

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Either Brown invests in real estate or he will lose money