Is a Valid Argument Always Considered Sound?

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SUMMARY

A valid argument is defined as one where the premises necessarily imply the conclusion, regardless of the truth of the premises. In contrast, a sound argument is both valid and contains only true premises, making the conclusion necessarily true. An example of a valid yet unsound argument is presented: "If 2+2=4, then Greg Bernhardt wears miniskirts. 2+2=4. Therefore, Greg Bernhardt wears miniskirts." This demonstrates that validity does not guarantee soundness.

PREREQUISITES
  • Understanding of deductive reasoning
  • Familiarity with logical premises and conclusions
  • Knowledge of the definitions of validity and soundness
  • Basic grasp of logical argument structures
NEXT STEPS
  • Study the differences between valid and sound arguments in depth
  • Explore examples of valid but unsound arguments
  • Learn about logical fallacies and their impact on argument soundness
  • Review resources on formal logic, such as "Logic Notes" for further clarification
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Students in critical reasoning courses, educators teaching logic, and anyone interested in enhancing their understanding of argumentation and logical structures.

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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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:
 
Last edited:
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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