'If-then' and validity (1)

So far I have suggested that we can simply see when an argument is valid or invalid. Most people who know what validity is have no problem (for example) recognising whether this argument is valid

I. Either Randolph is asleep or he's dead Randolph is not asleep __________ Randolph is dead

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II. Either Randolph is asleep or he's dead Randolph is asleep __________ Randolph is dead.

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Are they valid?

But we can make mistakes. For example you might still not feel sure at once about

III. If Randolph is dead, he is not asleep __________ If Randolph is asleep, he is not dead.

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Is it valid or invalid?

(Hint: forget what these particular statements state. Must any argument of this form have a true conclusion, if its premise is true?)

When in doubt, we can sometimes show invalidity by finding another argument with the same form whose premises are true, but its conclusion false. 3

Give an example to fit the invalid form

If P then Q Not P __________ Not Q.