Validity And Soundness - Practice Exercises

1. Which of the following statements correctly describes the concepts of validity and soundness in logical arguments?

Validity refers to whether the conclusion logically follows from the premises, while soundness additionally requires that all premises are true.

Soundness refers to whether the conclusion logically follows from the premises, while validity additionally requires that all premises are true.

Validity and soundness are interchangeable terms that both describe whether an argument is logically consistent.

Validity refers to whether the premises are true, while soundness refers to whether the conclusion is logically consistent.

Validity pertains to the logical structure of an argument, where the conclusion follows necessarily from the premises. Soundness, on the other hand, requires that the argument is valid and that all premises are actually true. Therefore, option A correctly distinguishes between validity and soundness in logical reasoning.

Explanation

Validity pertains to the logical structure of an argument, where the conclusion follows necessarily from the premises. Soundness, on the other hand, requires that the argument is valid and that all premises are actually true. Therefore, option A correctly distinguishes between validity and soundness in logical reasoning.

2. It is February.
February is in the wintertime.
So it must be snowing.

Check here if the argument is VALID.

Check here if the argument is SOUND.

Check here if the argument is NEITHER valid NOR sound.

This argument is neither valid NOR sound: the premises might make the conclusion *more likely*, but they don't *guarantee* that it's true, as of course it doesn't snow on every winter day in February.

Explanation

This argument is neither valid NOR sound: the premises might make the conclusion *more likely*, but they don't *guarantee* that it's true, as of course it doesn't snow on every winter day in February.

3. It is January. January is in the wintertime. So it must be winter.

The argument is VALID.

The argument is SOUND.

The argument is NEITHER valid NOR sound.

This argument is valid, but NOT sound: it is valid because if it *were* January, then given that January's in the wintertime it would follow that it's winter; but it's unsound because it's not actually January.

Explanation

This argument is valid, but NOT sound: it is valid because if it *were* January, then given that January's in the wintertime it would follow that it's winter; but it's unsound because it's not actually January.

4. February 17th is Ash Wednesday.
February 17th is this Wednesday.
So this Wednesday must be Ash Wednesday.

Check here if the argument is VALID.

Check here if the argument is SOUND.

Check here if the argument is NEITHER valid NOR sound.

This argument is both valid AND sound: the premises are true, and given what they say the conclusion has to follow; if the 17th is Ash Wednesday and this Wednesday is the 17th, then this Wednesday has got to be Ash Wednesday.

Explanation

This argument is both valid AND sound: the premises are true, and given what they say the conclusion has to follow; if the 17th is Ash Wednesday and this Wednesday is the 17th, then this Wednesday has got to be Ash Wednesday.

Submit

5. Either President Lincoln was assassinated, or he was killed in an accident.
President Lincoln was not killed in an accident.
Therefore, President Lincoln must have been assassinated.

Check here if the argument is VALID.

Check here if the argument is SOUND.

Check here if the argument is NEITHER valid NOR sound.

This argument is both valid AND sound: it is valid because the truth of the premises guarantees the truth of the conclusion (the first premise gives you two options, the second premise rules one of them out, and the conclusion chooses the other of the two); and it is sound because in addition to being valid the argument also has true premises.

Explanation

This argument is both valid AND sound: it is valid because the truth of the premises guarantees the truth of the conclusion (the first premise gives you two options, the second premise rules one of them out, and the conclusion chooses the other of the two); and it is sound because in addition to being valid the argument also has true premises.

Submit