Argument Soundness
Recall from the previous lesson that an argument can have problems from both of its fundamental parts:
- One or more of the assumed truths (premises) might be false.
- The newly derived truth (conclusion) may have been derived incorrectly.
In “Argument Validity”, we discussed how validity is only concerned with problems that stem from part 2. That said, if an argument is valid and its premises are verified as true, then it is sound. In other words, an argument is sound if and only if its conclusion is derived validly and its premises are verified as true (not merely assumbed to be so). Thus, it does not have any problems with either one of its fundamental parts.
Returning to our favorite example:
- If you hear barking, then there must be a dog.
- You heard barking.
- There must be a dog. (1, 2)
As we stated previously, this example is valid, but it is unsound. It is unsound because the first premise is false, the mere sound of barking does not always imply the presence of a dog.
It might not be apparent why we should treat validity separately from soundness. Why not just say, “Hey, there’s a problem with this argument!” without need for this classification? The short answer is that validity can be determined by argument form, which allows us to greatly generalize the study of arguments. This generalization allows us to study arguments at a higher-level regardless of their actual content, if an argument form is valid, then any argument that follows that form is also valid. Similarly, if an argument form is invalid, then any argument that follows that form is also invalid.
This “superpower” or “shortcut” to reasoning will become more apparent when we cover “Argument Form” and study the rules of inference. In the next lesson, we will talk about symbolizing statements and how doing so can aid us in recognizing argument form.
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Enhance your critical thinking skills with Symbols Logic. Unlock access to
the first studycard and the first level of all activities for free. Get the
app now:
Recall from the previous lesson that an argument can have problems from both of its fundamental parts:
- One or more of the assumed truths (premises) might be false.
- The newly derived truth (conclusion) may have been derived incorrectly.
In “Argument Validity”, we discussed how validity is only concerned with problems that stem from part 2. That said, if an argument is valid and its premises are verified as true, then it is sound. In other words, an argument is sound if and only if its conclusion is derived validly and its premises are verified as true (not merely assumbed to be so). Thus, it does not have any problems with either one of its fundamental parts.
Returning to our favorite example:
- If you hear barking, then there must be a dog.
- You heard barking.
- There must be a dog. (1, 2)
As we stated previously, this example is valid, but it is unsound. It is unsound because the first premise is false, the mere sound of barking does not always imply the presence of a dog.
It might not be apparent why we should treat validity separately from soundness. Why not just say, “Hey, there’s a problem with this argument!” without need for this classification? The short answer is that validity can be determined by argument form, which allows us to greatly generalize the study of arguments. This generalization allows us to study arguments at a higher-level regardless of their actual content, if an argument form is valid, then any argument that follows that form is also valid. Similarly, if an argument form is invalid, then any argument that follows that form is also invalid.
This “superpower” or “shortcut” to reasoning will become more apparent when we cover “Argument Form” and study the rules of inference. In the next lesson, we will talk about symbolizing statements and how doing so can aid us in recognizing argument form.
Want an interactive way to learn logic?
Enhance your critical thinking skills with Symbols Logic. Unlock access to the first studycard and the first level of all activities for free. Get the app now: