Additional information STRENGTHENS the analogy if it presents an additional way in which the two things being compared are alike AND that additional way is relevant. But, relevance is something that you have to have enough factual information to judge. For example, that a new teacher has the same last name as a favorite teacher is probably not relevant to the issue of whether you will also find him or her a good teacher.

Additional information WEAKENS the analogy if it presents relevant ways in which the two items are different. For example, that the new teacher is not funny probably implies that you will not like him or her if all of your favorite teachers are funny.

Additional information does not affect the analogy if it is not relevant.

If you disagree with the answer to an exercise, write a paragraph explaining why and turn it in to your instructor. You may be able to bring out a fact that the authors overlooked.