Most lecturers who are effective

Answer choices

1. A

   Correct65% picked this

   Some good communicators are

   Why this is right

   The people in the first sentence are lecturers, effective teachers, and eccentric. We're told that every effective teacher is a good communicator. So the people in the first sentence are lecturers, effective teachers, good communicators, and eccentric. That proves that some people are both eccentric and good communicators. More formally, we combine these two Some eccentric are effect teach effect ? good teach comm. and get this inference, Some eccentric are good comm.

   Skill tested: Must be True · how this choice captures the argument's function is the move to repeat next time.

   65%
2. B

   Too Strong: all Illegal Reversal4% picked this

   All good communicators are effective

   We can't say anything about all good communicators, because we were never told anything about that all good communicators. We know that some good communicators are effective teachers. The last sentence says this: effective teacher ? good comm. and this answer illegally reverses that: good comm ? effective teacher

   4%
3. C

   Out of Scope: not effective10% picked this

   Some lecturers who are not effective teachers are

   We only heard about teachers who are effective, so we have no information to support any inference about teachers are not effective.

   10%
4. D

   Too Strong: most Unknown Most Group16% picked this

   Most lecturers who are good communicators

   This answer talks about most [people who are lecturers and good communicators]. We never got a most fact about that group, so we can't make a most inference about that group. We only got a most fact about the group of [people who are lecturers and effective teachers]. People might be tempted to think, "Can't I just swap out effective with good communicator?" Anywhere we see "effective" we can add "good communicator", but we can't replace it and still be talking about the same group of people. Consider this example: "Most adults who are NFL players are paid over $1 million / year" "Every NFL player is a man." Could we just swap out "NFL player" for "man" and say, "Most adults who are men are paid over $1 million / year"? Of course not. We know that most adult males don't get paid that much. By changing from "most adults who are NFL players" to "most adults who are men" we went from talking about over 50% of a group of about 1000 people (NFL players) to talking about over 50% of a group of about 2 billion people (adult males).

   16%
5. E

   Out of Scope: not good communicator5% picked this

   Some noneccentric lecturers are effective teachers but are not

   We only received information about people who are good communicators, so we have no information to support any inference about people who are not good communicators.

   5%