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Sound vs. Valid Arguments

Of the two arguments provided in the digital story below which is valid and which is sound? When building an argument for an issue that is significant to you, do you think it is more important to be valid or sound?


<Voice of Man>

"The other day when I got home from work I heard a knock at our front door. It was a salesperson selling vacuum cleaners.

He had a vacuum with him that he claimed was the latest in vacuum cleaning technology. He asked me to come into the living room and then he guy dumped a huge pile of dirt on my white carpet! I was about to tell him to get lost when he vacuumed it all up and sure enough it was completely gone. I couldn't believe it, the carpet looked brand new!

Then he said...

<Voice of Man speaking for Salesman >

"Anyone who wants a comfortable, clean home needs this amazing vacuum cleaner. You certainly look like someone who likes having a really clean home. So, you definitely need this vacuum cleaner!"

<Returning to the Voice of the Man>

I told the salesperson he made a convincing argument but that I needed some time to think about it. So he agreed to come back in a few hours for my answer.

A few minutes later, my wife came home from work and I told her what happened.

She said...

<Voice of Speaking for Wife>

"Honey, our carpets are clean and we already have a working vacuum cleaner. We don't need a new one!"

<Returning to the Voice of the Man>

After she said that, the salesperson came back to the house and I had to tell him that though I do like our floors to be clean, based on what my wife said I'm not so sure we need a new vacuum cleaner. He didn't look too pleased about my decision but left his business card anyway. I closed the door, and I heard my wife yell from the kitchen, "That reminds me honey, it's your turn to vacuum the house!"

Solution Preview

I found a website that does a good job explaining the difference between valid and sound: http://atheism.about.com/od/logicalarguments/a/critiquing.htm.

As far as the script goes, the vacuum salesman has a valid argument because the "reasoning process behind the inferences is correct and that no ...

Solution Summary

Discusses the difference between a sound argument and a valid argument.