Is a Valid Argument Always Considered Sound?

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A valid argument is not the same as a sound argument. A valid argument is one where the premises logically lead to the conclusion, regardless of whether the premises are true. In contrast, a sound argument is valid and contains only true premises, making the conclusion necessarily true as well. It is possible to have a valid argument that is unsound if the premises are false. An example provided illustrates this: the argument "If 2+2=4, then Greg Bernhardt wears miniskirts; 2+2=4; therefore, Greg Bernhardt wears miniskirts" is valid in structure but unsound due to the questionable truth of the premises.
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I need a little clarification on some terminology being used in my crit. reasoning class: valid and sound.
Is a valid argument the same thing as a sound argument?
Or can you have a valid argument that is actually unsound?

Thanks!
 
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Math Is Hard said:
Is a valid argument the same thing as a sound argument?

No, an argument is valid if it is deductively valid. That is, if the premises necessarily imply the conclusion. But a valid argument need not have true premises. An argument is sound if it is valid, noncircular, and contains only true premises. In that case, the conclusion is not only necessarily implied by the premises, it is also necessarily true.

You may find these threads helpful:

Logic
Logic Notes

In posts 4, 5, and 6 of Logic Notes, I go into detail about validity and soundness.

Or can you have a valid argument that is actually unsound?

Yes, here's an example:

If 2+2=4, then Greg Bernhardt wears miniskirts.
2+2=4.
Therefore, Greg Bernhardt wears miniskirts.


It's perfectly valid, because the schema is valid:

p-->q.
q.
Therefore, q.


But are the premises true? I don't want to find out. :smile:
 
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Thanks for the help, Tom. The only problem now is going to be controlling the giggling during the exam when I start thinking back to your example! :smile:
 
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