Is a Valid Argument Always Considered Sound?

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In summary, a valid argument is one in which the conclusion necessarily follows from the premises, while a sound argument is one that is valid, noncircular, and contains only true premises. It is possible to have a valid argument that is unsound, as the truth of the premises is also important in determining the soundness of an argument. An example of a valid but unsound argument is if 2+2=4, then Greg Bernhardt wears miniskirts, 2+2=4, therefore Greg Bernhardt wears miniskirts.
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Math Is Hard
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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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  • #2
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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  • #3
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:
 

Related to Is a Valid Argument Always Considered Sound?

1. What is the difference between a valid and sound argument?

A valid argument is one in which the conclusion logically follows from the premises, meaning that if the premises are true, the conclusion must also be true. A sound argument, on the other hand, is a valid argument with true premises. This means that not only is the conclusion logically derived from the premises, but the premises themselves are also true.

2. Why is it important to distinguish between valid and sound arguments?

It is important to distinguish between valid and sound arguments because a valid argument can still have a false conclusion if the premises are false. A sound argument, on the other hand, ensures that the conclusion is true. This is crucial in the field of science, where conclusions must be based on accurate and reliable evidence.

3. How can you determine if an argument is valid or sound?

To determine if an argument is valid, you must first analyze the logical structure of the argument. If the conclusion logically follows from the premises, the argument is valid. To determine if an argument is sound, you must also assess the truthfulness of the premises. If both the logical structure and the premises are true, the argument is sound.

4. Can a valid argument have false premises?

Yes, a valid argument can have false premises. As long as the conclusion logically follows from the premises, the argument is considered valid. However, this does not necessarily mean that the conclusion is true, as the premises could still be false.

5. What is an example of a valid but unsound argument?

An example of a valid but unsound argument is: All mammals lay eggs. Dogs are mammals. Therefore, dogs lay eggs. This argument is valid because the conclusion logically follows from the premises, but it is not sound because the first premise is false. Not all mammals lay eggs, so the conclusion is not true.

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