Is this a valid argument?

Given: If a geometric figure starts at a point and extends forever in one direction, then it is a ray.

is a ray.

Conclusion:
starts at one point and extends forever in one direction.

Yes. This argument uses the Law of Detachment.

No. This is an improper use of the Law of Syllogism.

No. This is an improper use of the Law of Detachment.

Yes. This argument uses the Law of Syllogism.

1 answer

To determine if the argument is valid, let's break it down using the information provided.

  1. Given Statement: "If a geometric figure starts at a point and extends forever in one direction, then it is a ray."

    • This is a conditional (if-then) statement.
  2. Stated Fact: "is a ray."

    • This appears to be incomplete but implies that we are identifying some geometric figure as a ray.
  3. Conclusion: "starts at one point and extends forever in one direction."

    • This is the conclusion drawn based on the previous statements.

The given statement can be denoted as:

  • If \( P \) (a geometric figure starts at a point and extends forever in one direction), then \( Q \) (it is a ray).

The fact that "is a ray" can be interpreted as asserting \( Q \).

Now, to apply the Law of Detachment: If \( P \) implies \( Q \) (which it does), and we know \( Q \) is true (the figure is a ray), we can conclude that \( P \) (it starts at one point and extends forever in one direction) must also be true.

Thus:

  • Since we know a geometric figure is a ray (true), we can conclude that it starts at one point and extends forever in one direction (also true) based on our original statement.

Thus, the correct answer would be: Yes. This argument uses the Law of Detachment.