Instructions: Below is a conditional. Assume that it is true. You will be given an additional fact, which you should assume is true. You will finally be given a conclusion, starting with "Thus." If both the conditional and the additional fact were true, would the conclusion have to be true? If so, pick YES. If not, pick NO.

Conditional:

If the door to the study is locked from the inside, then the butler did it.

Fact:

The door to the study is locked from the inside.

Conclusion:

Thus, the butler did it.

Answer: If you assume that the conditional and fact above are true, must the conclusion also be true?

Yes, the conclusion must be true if the conditional and fact are true.

No, the conclusion might be false even if the conditional and fact are true.